/*-------------------------------------------------------------------------
*
* nodeAgg.c
* Routines to handle aggregate nodes.
*
* ExecAgg normally evaluates each aggregate in the following steps:
*
* transvalue = initcond
* foreach input_tuple do
* transvalue = transfunc(transvalue, input_value(s))
* result = finalfunc(transvalue, direct_argument(s))
*
* If a finalfunc is not supplied then the result is just the ending
* value of transvalue.
*
* Other behaviors can be selected by the "aggsplit" mode, which exists
* to support partial aggregation. It is possible to:
* * Skip running the finalfunc, so that the output is always the
* final transvalue state.
* * Substitute the combinefunc for the transfunc, so that transvalue
* states (propagated up from a child partial-aggregation step) are merged
* rather than processing raw input rows. (The statements below about
* the transfunc apply equally to the combinefunc, when it's selected.)
* * Apply the serializefunc to the output values (this only makes sense
* when skipping the finalfunc, since the serializefunc works on the
* transvalue data type).
* * Apply the deserializefunc to the input values (this only makes sense
* when using the combinefunc, for similar reasons).
* It is the planner's responsibility to connect up Agg nodes using these
* alternate behaviors in a way that makes sense, with partial aggregation
* results being fed to nodes that expect them.
*
* If a normal aggregate call specifies DISTINCT or ORDER BY, we sort the
* input tuples and eliminate duplicates (if required) before performing
* the above-depicted process. (However, we don't do that for ordered-set
* aggregates; their "ORDER BY" inputs are ordinary aggregate arguments
* so far as this module is concerned.) Note that partial aggregation
* is not supported in these cases, since we couldn't ensure global
* ordering or distinctness of the inputs.
*
* If transfunc is marked "strict" in pg_proc and initcond is NULL,
* then the first non-NULL input_value is assigned directly to transvalue,
* and transfunc isn't applied until the second non-NULL input_value.
* The agg's first input type and transtype must be the same in this case!
*
* If transfunc is marked "strict" then NULL input_values are skipped,
* keeping the previous transvalue. If transfunc is not strict then it
* is called for every input tuple and must deal with NULL initcond
* or NULL input_values for itself.
*
* If finalfunc is marked "strict" then it is not called when the
* ending transvalue is NULL, instead a NULL result is created
* automatically (this is just the usual handling of strict functions,
* of course). A non-strict finalfunc can make its own choice of
* what to return for a NULL ending transvalue.
*
* Ordered-set aggregates are treated specially in one other way: we
* evaluate any "direct" arguments and pass them to the finalfunc along
* with the transition value.
*
* A finalfunc can have additional arguments beyond the transvalue and
* any "direct" arguments, corresponding to the input arguments of the
* aggregate. These are always just passed as NULL. Such arguments may be
* needed to allow resolution of a polymorphic aggregate's result type.
*
* We compute aggregate input expressions and run the transition functions
* in a temporary econtext (aggstate->tmpcontext). This is reset at least
* once per input tuple, so when the transvalue datatype is
* pass-by-reference, we have to be careful to copy it into a longer-lived
* memory context, and free the prior value to avoid memory leakage. We
* store transvalues in another set of econtexts, aggstate->aggcontexts
* (one per grouping set, see below), which are also used for the hashtable
* structures in AGG_HASHED mode. These econtexts are rescanned, not just
* reset, at group boundaries so that aggregate transition functions can
* register shutdown callbacks via AggRegisterCallback.
*
* The node's regular econtext (aggstate->ss.ps.ps_ExprContext) is used to
* run finalize functions and compute the output tuple; this context can be
* reset once per output tuple.
*
* The executor's AggState node is passed as the fmgr "context" value in
* all transfunc and finalfunc calls. It is not recommended that the
* transition functions look at the AggState node directly, but they can
* use AggCheckCallContext() to verify that they are being called by
* nodeAgg.c (and not as ordinary SQL functions). The main reason a
* transition function might want to know this is so that it can avoid
* palloc'ing a fixed-size pass-by-ref transition value on every call:
* it can instead just scribble on and return its left input. Ordinarily
* it is completely forbidden for functions to modify pass-by-ref inputs,
* but in the aggregate case we know the left input is either the initial
* transition value or a previous function result, and in either case its
* value need not be preserved. See int8inc() for an example. Notice that
* the EEOP_AGG_PLAIN_TRANS step is coded to avoid a data copy step when
* the previous transition value pointer is returned. It is also possible
* to avoid repeated data copying when the transition value is an expanded
* object: to do that, the transition function must take care to return
* an expanded object that is in a child context of the memory context
* returned by AggCheckCallContext(). Also, some transition functions want
* to store working state in addition to the nominal transition value; they
* can use the memory context returned by AggCheckCallContext() to do that.
*
* Note: AggCheckCallContext() is available as of PostgreSQL 9.0. The
* AggState is available as context in earlier releases (back to 8.1),
* but direct examination of the node is needed to use it before 9.0.
*
* As of 9.4, aggregate transition functions can also use AggGetAggref()
* to get hold of the Aggref expression node for their aggregate call.
* This is mainly intended for ordered-set aggregates, which are not
* supported as window functions. (A regular aggregate function would
* need some fallback logic to use this, since there's no Aggref node
* for a window function.)
*
* Grouping sets:
*
* A list of grouping sets which is structurally equivalent to a ROLLUP
* clause (e.g. (a,b,c), (a,b), (a)) can be processed in a single pass over
* ordered data. We do this by keeping a separate set of transition values
* for each grouping set being concurrently processed; for each input tuple
* we update them all, and on group boundaries we reset those states
* (starting at the front of the list) whose grouping values have changed
* (the list of grouping sets is ordered from most specific to least
* specific).
*
* Where more complex grouping sets are used, we break them down into
* "phases", where each phase has a different sort order (except phase 0
* which is reserved for hashing). During each phase but the last, the
* input tuples are additionally stored in a tuplesort which is keyed to the
* next phase's sort order; during each phase but the first, the input
* tuples are drawn from the previously sorted data. (The sorting of the
* data for the first phase is handled by the planner, as it might be
* satisfied by underlying nodes.)
*
* Hashing can be mixed with sorted grouping. To do this, we have an
* AGG_MIXED strategy that populates the hashtables during the first sorted
* phase, and switches to reading them out after completing all sort phases.
* We can also support AGG_HASHED with multiple hash tables and no sorting
* at all.
*
* From the perspective of aggregate transition and final functions, the
* only issue regarding grouping sets is this: a single call site (flinfo)
* of an aggregate function may be used for updating several different
* transition values in turn. So the function must not cache in the flinfo
* anything which logically belongs as part of the transition value (most
* importantly, the memory context in which the transition value exists).
* The support API functions (AggCheckCallContext, AggRegisterCallback) are
* sensitive to the grouping set for which the aggregate function is
* currently being called.
*
* Plan structure:
*
* What we get from the planner is actually one "real" Agg node which is
* part of the plan tree proper, but which optionally has an additional list
* of Agg nodes hung off the side via the "chain" field. This is because an
* Agg node happens to be a convenient representation of all the data we
* need for grouping sets.
*
* For many purposes, we treat the "real" node as if it were just the first
* node in the chain. The chain must be ordered such that hashed entries
* come before sorted/plain entries; the real node is marked AGG_MIXED if
* there are both types present (in which case the real node describes one
* of the hashed groupings, other AGG_HASHED nodes may optionally follow in
* the chain, followed in turn by AGG_SORTED or (one) AGG_PLAIN node). If
* the real node is marked AGG_HASHED or AGG_SORTED, then all the chained
* nodes must be of the same type; if it is AGG_PLAIN, there can be no
* chained nodes.
*
* We collect all hashed nodes into a single "phase", numbered 0, and create
* a sorted phase (numbered 1..n) for each AGG_SORTED or AGG_PLAIN node.
* Phase 0 is allocated even if there are no hashes, but remains unused in
* that case.
*
* AGG_HASHED nodes actually refer to only a single grouping set each,
* because for each hashed grouping we need a separate grpColIdx and
* numGroups estimate. AGG_SORTED nodes represent a "rollup", a list of
* grouping sets that share a sort order. Each AGG_SORTED node other than
* the first one has an associated Sort node which describes the sort order
* to be used; the first sorted node takes its input from the outer subtree,
* which the planner has already arranged to provide ordered data.
*
* Memory and ExprContext usage:
*
* Because we're accumulating aggregate values across input rows, we need to
* use more memory contexts than just simple input/output tuple contexts.
* In fact, for a rollup, we need a separate context for each grouping set
* so that we can reset the inner (finer-grained) aggregates on their group
* boundaries while continuing to accumulate values for outer
* (coarser-grained) groupings. On top of this, we might be simultaneously
* populating hashtables; however, we only need one context for all the
* hashtables.
*
* So we create an array, aggcontexts, with an ExprContext for each grouping
* set in the largest rollup that we're going to process, and use the
* per-tuple memory context of those ExprContexts to store the aggregate
* transition values. hashcontext is the single context created to support
* all hash tables.
*
* Transition / Combine function invocation:
*
* For performance reasons transition functions, including combine
* functions, aren't invoked one-by-one from nodeAgg.c after computing
* arguments using the expression evaluation engine. Instead
* ExecBuildAggTrans() builds one large expression that does both argument
* evaluation and transition function invocation. That avoids performance
* issues due to repeated uses of expression evaluation, complications due
* to filter expressions having to be evaluated early, and allows to JIT
* the entire expression into one native function.
*
* Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/executor/nodeAgg.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/htup_details.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_aggregate.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "executor/executor.h"
#include "executor/nodeAgg.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/tlist.h"
#include "parser/parse_agg.h"
#include "parser/parse_coerce.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/syscache.h"
#include "utils/tuplesort.h"
#include "utils/datum.h"
static void select_current_set(AggState *aggstate, int setno, bool is_hash);
static void initialize_phase(AggState *aggstate, int newphase);
static TupleTableSlot *fetch_input_tuple(AggState *aggstate);
static void initialize_aggregates(AggState *aggstate,
AggStatePerGroup *pergroups,
int numReset);
static void advance_transition_function(AggState *aggstate,
AggStatePerTrans pertrans,
AggStatePerGroup pergroupstate);
static void advance_aggregates(AggState *aggstate);
static void process_ordered_aggregate_single(AggState *aggstate,
AggStatePerTrans pertrans,
AggStatePerGroup pergroupstate);
static void process_ordered_aggregate_multi(AggState *aggstate,
AggStatePerTrans pertrans,
AggStatePerGroup pergroupstate);
static void finalize_aggregate(AggState *aggstate,
AggStatePerAgg peragg,
AggStatePerGroup pergroupstate,
Datum *resultVal, bool *resultIsNull);
static void finalize_partialaggregate(AggState *aggstate,
AggStatePerAgg peragg,
AggStatePerGroup pergroupstate,
Datum *resultVal, bool *resultIsNull);
static void prepare_projection_slot(AggState *aggstate,
TupleTableSlot *slot,
int currentSet);
static void finalize_aggregates(AggState *aggstate,
AggStatePerAgg peragg,
AggStatePerGroup pergroup);
static TupleTableSlot *project_aggregates(AggState *aggstate);
static Bitmapset *find_unaggregated_cols(AggState *aggstate);
static bool find_unaggregated_cols_walker(Node *node, Bitmapset **colnos);
static void build_hash_table(AggState *aggstate);
static TupleHashEntryData *lookup_hash_entry(AggState *aggstate);
static void lookup_hash_entries(AggState *aggstate);
static TupleTableSlot *agg_retrieve_direct(AggState *aggstate);
static void agg_fill_hash_table(AggState *aggstate);
static TupleTableSlot *agg_retrieve_hash_table(AggState *aggstate);
static Datum GetAggInitVal(Datum textInitVal, Oid transtype);
static void build_pertrans_for_aggref(AggStatePerTrans pertrans,
AggState *aggstate, EState *estate,
Aggref *aggref, Oid aggtransfn, Oid aggtranstype,
Oid aggserialfn, Oid aggdeserialfn,
Datum initValue, bool initValueIsNull,
Oid *inputTypes, int numArguments);
static int find_compatible_peragg(Aggref *newagg, AggState *aggstate,
int lastaggno, List **same_input_transnos);
static int find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
bool shareable,
Oid aggtransfn, Oid aggtranstype,
Oid aggserialfn, Oid aggdeserialfn,
Datum initValue, bool initValueIsNull,
List *transnos);
/*
* Select the current grouping set; affects current_set and
* curaggcontext.
*/
static void
select_current_set(AggState *aggstate, int setno, bool is_hash)
{
/* when changing this, also adapt ExecInterpExpr() and friends */
if (is_hash)
aggstate->curaggcontext = aggstate->hashcontext;
else
aggstate->curaggcontext = aggstate->aggcontexts[setno];
aggstate->current_set = setno;
}
/*
* Switch to phase "newphase", which must either be 0 or 1 (to reset) or
* current_phase + 1. Juggle the tuplesorts accordingly.
*
* Phase 0 is for hashing, which we currently handle last in the AGG_MIXED
* case, so when entering phase 0, all we need to do is drop open sorts.
*/
static void
initialize_phase(AggState *aggstate, int newphase)
{
Assert(newphase <= 1 || newphase == aggstate->current_phase + 1);
/*
* Whatever the previous state, we're now done with whatever input
* tuplesort was in use.
*/
if (aggstate->sort_in)
{
tuplesort_end(aggstate->sort_in);
aggstate->sort_in = NULL;
}
if (newphase <= 1)
{
/*
* Discard any existing output tuplesort.
*/
if (aggstate->sort_out)
{
tuplesort_end(aggstate->sort_out);
aggstate->sort_out = NULL;
}
}
else
{
/*
* The old output tuplesort becomes the new input one, and this is the
* right time to actually sort it.
*/
aggstate->sort_in = aggstate->sort_out;
aggstate->sort_out = NULL;
Assert(aggstate->sort_in);
tuplesort_performsort(aggstate->sort_in);
}
/*
* If this isn't the last phase, we need to sort appropriately for the
* next phase in sequence.
*/
if (newphase > 0 && newphase < aggstate->numphases - 1)
{
Sort *sortnode = aggstate->phases[newphase + 1].sortnode;
PlanState *outerNode = outerPlanState(aggstate);
TupleDesc tupDesc = ExecGetResultType(outerNode);
aggstate->sort_out = tuplesort_begin_heap(tupDesc,
sortnode->numCols,
sortnode->sortColIdx,
sortnode->sortOperators,
sortnode->collations,
sortnode->nullsFirst,
work_mem,
NULL, false);
}
aggstate->current_phase = newphase;
aggstate->phase = &aggstate->phases[newphase];
}
/*
* Fetch a tuple from either the outer plan (for phase 1) or from the sorter
* populated by the previous phase. Copy it to the sorter for the next phase
* if any.
*
* Callers cannot rely on memory for tuple in returned slot remaining valid
* past any subsequently fetched tuple.
*/
static TupleTableSlot *
fetch_input_tuple(AggState *aggstate)
{
TupleTableSlot *slot;
if (aggstate->sort_in)
{
/* make sure we check for interrupts in either path through here */
CHECK_FOR_INTERRUPTS();
if (!tuplesort_gettupleslot(aggstate->sort_in, true, false,
aggstate->sort_slot, NULL))
return NULL;
slot = aggstate->sort_slot;
}
else
slot = ExecProcNode(outerPlanState(aggstate));
if (!TupIsNull(slot) && aggstate->sort_out)
tuplesort_puttupleslot(aggstate->sort_out, slot);
return slot;
}
/*
* (Re)Initialize an individual aggregate.
*
* This function handles only one grouping set, already set in
* aggstate->current_set.
*
* When called, CurrentMemoryContext should be the per-query context.
*/
static void
initialize_aggregate(AggState *aggstate, AggStatePerTrans pertrans,
AggStatePerGroup pergroupstate)
{
/*
* Start a fresh sort operation for each DISTINCT/ORDER BY aggregate.
*/
if (pertrans->numSortCols > 0)
{
/*
* In case of rescan, maybe there could be an uncompleted sort
* operation? Clean it up if so.
*/
if (pertrans->sortstates[aggstate->current_set])
tuplesort_end(pertrans->sortstates[aggstate->current_set]);
/*
* We use a plain Datum sorter when there's a single input column;
* otherwise sort the full tuple. (See comments for
* process_ordered_aggregate_single.)
*/
if (pertrans->numInputs == 1)
{
Form_pg_attribute attr = TupleDescAttr(pertrans->sortdesc, 0);
pertrans->sortstates[aggstate->current_set] =
tuplesort_begin_datum(attr->atttypid,
pertrans->sortOperators[0],
pertrans->sortCollations[0],
pertrans->sortNullsFirst[0],
work_mem, NULL, false);
}
else
pertrans->sortstates[aggstate->current_set] =
tuplesort_begin_heap(pertrans->sortdesc,
pertrans->numSortCols,
pertrans->sortColIdx,
pertrans->sortOperators,
pertrans->sortCollations,
pertrans->sortNullsFirst,
work_mem, NULL, false);
}
/*
* (Re)set transValue to the initial value.
*
* Note that when the initial value is pass-by-ref, we must copy it (into
* the aggcontext) since we will pfree the transValue later.
*/
if (pertrans->initValueIsNull)
pergroupstate->transValue = pertrans->initValue;
else
{
MemoryContext oldContext;
oldContext = MemoryContextSwitchTo(
aggstate->curaggcontext->ecxt_per_tuple_memory);
pergroupstate->transValue = datumCopy(pertrans->initValue,
pertrans->transtypeByVal,
pertrans->transtypeLen);
MemoryContextSwitchTo(oldContext);
}
pergroupstate->transValueIsNull = pertrans->initValueIsNull;
/*
* If the initial value for the transition state doesn't exist in the
* pg_aggregate table then we will let the first non-NULL value returned
* from the outer procNode become the initial value. (This is useful for
* aggregates like max() and min().) The noTransValue flag signals that we
* still need to do this.
*/
pergroupstate->noTransValue = pertrans->initValueIsNull;
}
/*
* Initialize all aggregate transition states for a new group of input values.
*
* If there are multiple grouping sets, we initialize only the first numReset
* of them (the grouping sets are ordered so that the most specific one, which
* is reset most often, is first). As a convenience, if numReset is 0, we
* reinitialize all sets.
*
* NB: This cannot be used for hash aggregates, as for those the grouping set
* number has to be specified from further up.
*
* When called, CurrentMemoryContext should be the per-query context.
*/
static void
initialize_aggregates(AggState *aggstate,
AggStatePerGroup *pergroups,
int numReset)
{
int transno;
int numGroupingSets = Max(aggstate->phase->numsets, 1);
int setno = 0;
int numTrans = aggstate->numtrans;
AggStatePerTrans transstates = aggstate->pertrans;
if (numReset == 0)
numReset = numGroupingSets;
for (setno = 0; setno < numReset; setno++)
{
AggStatePerGroup pergroup = pergroups[setno];
select_current_set(aggstate, setno, false);
for (transno = 0; transno < numTrans; transno++)
{
AggStatePerTrans pertrans = &transstates[transno];
AggStatePerGroup pergroupstate = &pergroup[transno];
initialize_aggregate(aggstate, pertrans, pergroupstate);
}
}
}
/*
* Given new input value(s), advance the transition function of one aggregate
* state within one grouping set only (already set in aggstate->current_set)
*
* The new values (and null flags) have been preloaded into argument positions
* 1 and up in pertrans->transfn_fcinfo, so that we needn't copy them again to
* pass to the transition function. We also expect that the static fields of
* the fcinfo are already initialized; that was done by ExecInitAgg().
*
* It doesn't matter which memory context this is called in.
*/
static void
advance_transition_function(AggState *aggstate,
AggStatePerTrans pertrans,
AggStatePerGroup pergroupstate)
{
FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
MemoryContext oldContext;
Datum newVal;
if (pertrans->transfn.fn_strict)
{
/*
* For a strict transfn, nothing happens when there's a NULL input; we
* just keep the prior transValue.
*/
int numTransInputs = pertrans->numTransInputs;
int i;
for (i = 1; i <= numTransInputs; i++)
{
if (fcinfo->argnull[i])
return;
}
if (pergroupstate->noTransValue)
{
/*
* transValue has not been initialized. This is the first non-NULL
* input value. We use it as the initial value for transValue. (We
* already checked that the agg's input type is binary-compatible
* with its transtype, so straight copy here is OK.)
*
* We must copy the datum into aggcontext if it is pass-by-ref. We
* do not need to pfree the old transValue, since it's NULL.
*/
oldContext = MemoryContextSwitchTo(
aggstate->curaggcontext->ecxt_per_tuple_memory);
pergroupstate->transValue = datumCopy(fcinfo->arg[1],
pertrans->transtypeByVal,
pertrans->transtypeLen);
pergroupstate->transValueIsNull = false;
pergroupstate->noTransValue = false;
MemoryContextSwitchTo(oldContext);
return;
}
if (pergroupstate->transValueIsNull)
{
/*
* Don't call a strict function with NULL inputs. Note it is
* possible to get here despite the above tests, if the transfn is
* strict *and* returned a NULL on a prior cycle. If that happens
* we will propagate the NULL all the way to the end.
*/
return;
}
}
/* We run the transition functions in per-input-tuple memory context */
oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
/* set up aggstate->curpertrans for AggGetAggref() */
aggstate->curpertrans = pertrans;
/*
* OK to call the transition function
*/
fcinfo->arg[0] = pergroupstate->transValue;
fcinfo->argnull[0] = pergroupstate->transValueIsNull;
fcinfo->isnull = false; /* just in case transfn doesn't set it */
newVal = FunctionCallInvoke(fcinfo);
aggstate->curpertrans = NULL;
/*
* If pass-by-ref datatype, must copy the new value into aggcontext and
* free the prior transValue. But if transfn returned a pointer to its
* first input, we don't need to do anything. Also, if transfn returned a
* pointer to a R/W expanded object that is already a child of the
* aggcontext, assume we can adopt that value without copying it.
*/
if (!pertrans->transtypeByVal &&
DatumGetPointer(newVal) != DatumGetPointer(pergroupstate->transValue))
{
if (!fcinfo->isnull)
{
MemoryContextSwitchTo(aggstate->curaggcontext->ecxt_per_tuple_memory);
if (DatumIsReadWriteExpandedObject(newVal,
false,
pertrans->transtypeLen) &&
MemoryContextGetParent(DatumGetEOHP(newVal)->eoh_context) == CurrentMemoryContext)
/* do nothing */ ;
else
newVal = datumCopy(newVal,
pertrans->transtypeByVal,
pertrans->transtypeLen);
}
if (!pergroupstate->transValueIsNull)
{
if (DatumIsReadWriteExpandedObject(pergroupstate->transValue,
false,
pertrans->transtypeLen))
DeleteExpandedObject(pergroupstate->transValue);
else
pfree(DatumGetPointer(pergroupstate->transValue));
}
}
pergroupstate->transValue = newVal;
pergroupstate->transValueIsNull = fcinfo->isnull;
MemoryContextSwitchTo(oldContext);
}
/*
* Advance each aggregate transition state for one input tuple. The input
* tuple has been stored in tmpcontext->ecxt_outertuple, so that it is
* accessible to ExecEvalExpr.
*
* We have two sets of transition states to handle: one for sorted aggregation
* and one for hashed; we do them both here, to avoid multiple evaluation of
* the inputs.
*
* When called, CurrentMemoryContext should be the per-query context.
*/
static void
advance_aggregates(AggState *aggstate)
{
bool dummynull;
ExecEvalExprSwitchContext(aggstate->phase->evaltrans,
aggstate->tmpcontext,
&dummynull);
}
/*
* Run the transition function for a DISTINCT or ORDER BY aggregate
* with only one input. This is called after we have completed
* entering all the input values into the sort object. We complete the
* sort, read out the values in sorted order, and run the transition
* function on each value (applying DISTINCT if appropriate).
*
* Note that the strictness of the transition function was checked when
* entering the values into the sort, so we don't check it again here;
* we just apply standard SQL DISTINCT logic.
*
* The one-input case is handled separately from the multi-input case
* for performance reasons: for single by-value inputs, such as the
* common case of count(distinct id), the tuplesort_getdatum code path
* is around 300% faster. (The speedup for by-reference types is less
* but still noticeable.)
*
* This function handles only one grouping set (already set in
* aggstate->current_set).
*
* When called, CurrentMemoryContext should be the per-query context.
*/
static void
process_ordered_aggregate_single(AggState *aggstate,
AggStatePerTrans pertrans,
AggStatePerGroup pergroupstate)
{
Datum oldVal = (Datum) 0;
bool oldIsNull = true;
bool haveOldVal = false;
MemoryContext workcontext = aggstate->tmpcontext->ecxt_per_tuple_memory;
MemoryContext oldContext;
bool isDistinct = (pertrans->numDistinctCols > 0);
Datum newAbbrevVal = (Datum) 0;
Datum oldAbbrevVal = (Datum) 0;
FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
Datum *newVal;
bool *isNull;
Assert(pertrans->numDistinctCols < 2);
tuplesort_performsort(pertrans->sortstates[aggstate->current_set]);
/* Load the column into argument 1 (arg 0 will be transition value) */
newVal = fcinfo->arg + 1;
isNull = fcinfo->argnull + 1;
/*
* Note: if input type is pass-by-ref, the datums returned by the sort are
* freshly palloc'd in the per-query context, so we must be careful to
* pfree them when they are no longer needed.
*/
while (tuplesort_getdatum(pertrans->sortstates[aggstate->current_set],
true, newVal, isNull, &newAbbrevVal))
{
/*
* Clear and select the working context for evaluation of the equality
* function and transition function.
*/
MemoryContextReset(workcontext);
oldContext = MemoryContextSwitchTo(workcontext);
/*
* If DISTINCT mode, and not distinct from prior, skip it.
*
* Note: we assume equality functions don't care about collation.
*/
if (isDistinct &&
haveOldVal &&
((oldIsNull && *isNull) ||
(!oldIsNull && !*isNull &&
oldAbbrevVal == newAbbrevVal &&
DatumGetBool(FunctionCall2(&pertrans->equalfnOne,
oldVal, *newVal)))))
{
/* equal to prior, so forget this one */
if (!pertrans->inputtypeByVal && !*isNull)
pfree(DatumGetPointer(*newVal));
}
else
{
advance_transition_function(aggstate, pertrans, pergroupstate);
/* forget the old value, if any */
if (!oldIsNull && !pertrans->inputtypeByVal)
pfree(DatumGetPointer(oldVal));
/* and remember the new one for subsequent equality checks */
oldVal = *newVal;
oldAbbrevVal = newAbbrevVal;
oldIsNull = *isNull;
haveOldVal = true;
}
MemoryContextSwitchTo(oldContext);
}
if (!oldIsNull && !pertrans->inputtypeByVal)
pfree(DatumGetPointer(oldVal));
tuplesort_end(pertrans->sortstates[aggstate->current_set]);
pertrans->sortstates[aggstate->current_set] = NULL;
}
/*
* Run the transition function for a DISTINCT or ORDER BY aggregate
* with more than one input. This is called after we have completed
* entering all the input values into the sort object. We complete the
* sort, read out the values in sorted order, and run the transition
* function on each value (applying DISTINCT if appropriate).
*
* This function handles only one grouping set (already set in
* aggstate->current_set).
*
* When called, CurrentMemoryContext should be the per-query context.
*/
static void
process_ordered_aggregate_multi(AggState *aggstate,
AggStatePerTrans pertrans,
AggStatePerGroup pergroupstate)
{
ExprContext *tmpcontext = aggstate->tmpcontext;
FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
TupleTableSlot *slot1 = pertrans->sortslot;
TupleTableSlot *slot2 = pertrans->uniqslot;
int numTransInputs = pertrans->numTransInputs;
int numDistinctCols = pertrans->numDistinctCols;
Datum newAbbrevVal = (Datum) 0;
Datum oldAbbrevVal = (Datum) 0;
bool haveOldValue = false;
TupleTableSlot *save = aggstate->tmpcontext->ecxt_outertuple;
int i;
tuplesort_performsort(pertrans->sortstates[aggstate->current_set]);
ExecClearTuple(slot1);
if (slot2)
ExecClearTuple(slot2);
while (tuplesort_gettupleslot(pertrans->sortstates[aggstate->current_set],
true, true, slot1, &newAbbrevVal))
{
CHECK_FOR_INTERRUPTS();
tmpcontext->ecxt_outertuple = slot1;
tmpcontext->ecxt_innertuple = slot2;
if (numDistinctCols == 0 ||
!haveOldValue ||
newAbbrevVal != oldAbbrevVal ||
!ExecQual(pertrans->equalfnMulti, tmpcontext))
{
/*
* Extract the first numTransInputs columns as datums to pass to
* the transfn.
*/
slot_getsomeattrs(slot1, numTransInputs);
/* Load values into fcinfo */
/* Start from 1, since the 0th arg will be the transition value */
for (i = 0; i < numTransInputs; i++)
{
fcinfo->arg[i + 1] = slot1->tts_values[i];
fcinfo->argnull[i + 1] = slot1->tts_isnull[i];
}
advance_transition_function(aggstate, pertrans, pergroupstate);
if (numDistinctCols > 0)
{
/* swap the slot pointers to retain the current tuple */
TupleTableSlot *tmpslot = slot2;
slot2 = slot1;
slot1 = tmpslot;
/* avoid ExecQual() calls by reusing abbreviated keys */
oldAbbrevVal = newAbbrevVal;
haveOldValue = true;
}
}
/* Reset context each time */
ResetExprContext(tmpcontext);
ExecClearTuple(slot1);
}
if (slot2)
ExecClearTuple(slot2);
tuplesort_end(pertrans->sortstates[aggstate->current_set]);
pertrans->sortstates[aggstate->current_set] = NULL;
/* restore previous slot, potentially in use for grouping sets */
tmpcontext->ecxt_outertuple = save;
}
/*
* Compute the final value of one aggregate.
*
* This function handles only one grouping set (already set in
* aggstate->current_set).
*
* The finalfunction will be run, and the result delivered, in the
* output-tuple context; caller's CurrentMemoryContext does not matter.
*
* The finalfn uses the state as set in the transno. This also might be
* being used by another aggregate function, so it's important that we do
* nothing destructive here.
*/
static void
finalize_aggregate(AggState *aggstate,
AggStatePerAgg peragg,
AggStatePerGroup pergroupstate,
Datum *resultVal, bool *resultIsNull)
{
FunctionCallInfoData fcinfo;
bool anynull = false;
MemoryContext oldContext;
int i;
ListCell *lc;
AggStatePerTrans pertrans = &aggstate->pertrans[peragg->transno];
oldContext = MemoryContextSwitchTo(aggstate->ss.ps.ps_ExprContext->ecxt_per_tuple_memory);
/*
* Evaluate any direct arguments. We do this even if there's no finalfn
* (which is unlikely anyway), so that side-effects happen as expected.
* The direct arguments go into arg positions 1 and up, leaving position 0
* for the transition state value.
*/
i = 1;
foreach(lc, peragg->aggdirectargs)
{
ExprState *expr = (ExprState *) lfirst(lc);
fcinfo.arg[i] = ExecEvalExpr(expr,
aggstate->ss.ps.ps_ExprContext,
&fcinfo.argnull[i]);
anynull |= fcinfo.argnull[i];
i++;
}
/*
* Apply the agg's finalfn if one is provided, else return transValue.
*/
if (OidIsValid(peragg->finalfn_oid))
{
int numFinalArgs = peragg->numFinalArgs;
/* set up aggstate->curperagg for AggGetAggref() */
aggstate->curperagg = peragg;
InitFunctionCallInfoData(fcinfo, &peragg->finalfn,
numFinalArgs,
pertrans->aggCollation,
(void *) aggstate, NULL);
/* Fill in the transition state value */
fcinfo.arg[0] = MakeExpandedObjectReadOnly(pergroupstate->transValue,
pergroupstate->transValueIsNull,
pertrans->transtypeLen);
fcinfo.argnull[0] = pergroupstate->transValueIsNull;
anynull |= pergroupstate->transValueIsNull;
/* Fill any remaining argument positions with nulls */
for (; i < numFinalArgs; i++)
{
fcinfo.arg[i] = (Datum) 0;
fcinfo.argnull[i] = true;
anynull = true;
}
if (fcinfo.flinfo->fn_strict && anynull)
{
/* don't call a strict function with NULL inputs */
*resultVal = (Datum) 0;
*resultIsNull = true;
}
else
{
*resultVal = FunctionCallInvoke(&fcinfo);
*resultIsNull = fcinfo.isnull;
}
aggstate->curperagg = NULL;
}
else
{
/* Don't need MakeExpandedObjectReadOnly; datumCopy will copy it */
*resultVal = pergroupstate->transValue;
*resultIsNull = pergroupstate->transValueIsNull;
}
/*
* If result is pass-by-ref, make sure it is in the right context.
*/
if (!peragg->resulttypeByVal && !*resultIsNull &&
!MemoryContextContains(CurrentMemoryContext,
DatumGetPointer(*resultVal)))
*resultVal = datumCopy(*resultVal,
peragg->resulttypeByVal,
peragg->resulttypeLen);
MemoryContextSwitchTo(oldContext);
}
/*
* Compute the output value of one partial aggregate.
*
* The serialization function will be run, and the result delivered, in the
* output-tuple context; caller's CurrentMemoryContext does not matter.
*/
static void
finalize_partialaggregate(AggState *aggstate,
AggStatePerAgg peragg,
AggStatePerGroup pergroupstate,
Datum *resultVal, bool *resultIsNull)
{
AggStatePerTrans pertrans = &aggstate->pertrans[peragg->transno];
MemoryContext oldContext;
oldContext = MemoryContextSwitchTo(aggstate->ss.ps.ps_ExprContext->ecxt_per_tuple_memory);
/*
* serialfn_oid will be set if we must serialize the transvalue before
* returning it
*/
if (OidIsValid(pertrans->serialfn_oid))
{
/* Don't call a strict serialization function with NULL input. */
if (pertrans->serialfn.fn_strict && pergroupstate->transValueIsNull)
{
*resultVal = (Datum) 0;
*resultIsNull = true;
}
else
{
FunctionCallInfo fcinfo = &pertrans->serialfn_fcinfo;
fcinfo->arg[0] = MakeExpandedObjectReadOnly(pergroupstate->transValue,
pergroupstate->transValueIsNull,
pertrans->transtypeLen);
fcinfo->argnull[0] = pergroupstate->transValueIsNull;
*resultVal = FunctionCallInvoke(fcinfo);
*resultIsNull = fcinfo->isnull;
}
}
else
{
/* Don't need MakeExpandedObjectReadOnly; datumCopy will copy it */
*resultVal = pergroupstate->transValue;
*resultIsNull = pergroupstate->transValueIsNull;
}
/* If result is pass-by-ref, make sure it is in the right context. */
if (!peragg->resulttypeByVal && !*resultIsNull &&
!MemoryContextContains(CurrentMemoryContext,
DatumGetPointer(*resultVal)))
*resultVal = datumCopy(*resultVal,
peragg->resulttypeByVal,
peragg->resulttypeLen);
MemoryContextSwitchTo(oldContext);
}
/*
* Prepare to finalize and project based on the specified representative tuple
* slot and grouping set.
*
* In the specified tuple slot, force to null all attributes that should be
* read as null in the context of the current grouping set. Also stash the
* current group bitmap where GroupingExpr can get at it.
*
* This relies on three conditions:
*
* 1) Nothing is ever going to try and extract the whole tuple from this slot,
* only reference it in evaluations, which will only access individual
* attributes.
*
* 2) No system columns are going to need to be nulled. (If a system column is
* referenced in a group clause, it is actually projected in the outer plan
* tlist.)
*
* 3) Within a given phase, we never need to recover the value of an attribute
* once it has been set to null.
*
* Poking into the slot this way is a bit ugly, but the consensus is that the
* alternative was worse.
*/
static void
prepare_projection_slot(AggState *aggstate, TupleTableSlot *slot, int currentSet)
{
if (aggstate->phase->grouped_cols)
{
Bitmapset *grouped_cols = aggstate->phase->grouped_cols[currentSet];
aggstate->grouped_cols = grouped_cols;
if (slot->tts_isempty)
{
/*
* Force all values to be NULL if working on an empty input tuple
* (i.e. an empty grouping set for which no input rows were
* supplied).
*/
ExecStoreAllNullTuple(slot);
}
else if (aggstate->all_grouped_cols)
{
ListCell *lc;
/* all_grouped_cols is arranged in desc order */
slot_getsomeattrs(slot, linitial_int(aggstate->all_grouped_cols));
foreach(lc, aggstate->all_grouped_cols)
{
int attnum = lfirst_int(lc);
if (!bms_is_member(attnum, grouped_cols))
slot->tts_isnull[attnum - 1] = true;
}
}
}
}
/*
* Compute the final value of all aggregates for one group.
*
* This function handles only one grouping set at a time, which the caller must
* have selected. It's also the caller's responsibility to adjust the supplied
* pergroup parameter to point to the current set's transvalues.
*
* Results are stored in the output econtext aggvalues/aggnulls.
*/
static void
finalize_aggregates(AggState *aggstate,
AggStatePerAgg peraggs,
AggStatePerGroup pergroup)
{
ExprContext *econtext = aggstate->ss.ps.ps_ExprContext;
Datum *aggvalues = econtext->ecxt_aggvalues;
bool *aggnulls = econtext->ecxt_aggnulls;
int aggno;
int transno;
/*
* If there were any DISTINCT and/or ORDER BY aggregates, sort their
* inputs and run the transition functions.
*/
for (transno = 0; transno < aggstate->numtrans; transno++)
{
AggStatePerTrans pertrans = &aggstate->pertrans[transno];
AggStatePerGroup pergroupstate;
pergroupstate = &pergroup[transno];
if (pertrans->numSortCols > 0)
{
Assert(aggstate->aggstrategy != AGG_HASHED &&
aggstate->aggstrategy != AGG_MIXED);
if (pertrans->numInputs == 1)
process_ordered_aggregate_single(aggstate,
pertrans,
pergroupstate);
else
process_ordered_aggregate_multi(aggstate,
pertrans,
pergroupstate);
}
}
/*
* Run the final functions.
*/
for (aggno = 0; aggno < aggstate->numaggs; aggno++)
{
AggStatePerAgg peragg = &peraggs[aggno];
int transno = peragg->transno;
AggStatePerGroup pergroupstate;
pergroupstate = &pergroup[transno];
if (DO_AGGSPLIT_SKIPFINAL(aggstate->aggsplit))
finalize_partialaggregate(aggstate, peragg, pergroupstate,
&aggvalues[aggno], &aggnulls[aggno]);
else
finalize_aggregate(aggstate, peragg, pergroupstate,
&aggvalues[aggno], &aggnulls[aggno]);
}
}
/*
* Project the result of a group (whose aggs have already been calculated by
* finalize_aggregates). Returns the result slot, or NULL if no row is
* projected (suppressed by qual).
*/
static TupleTableSlot *
project_aggregates(AggState *aggstate)
{
ExprContext *econtext = aggstate->ss.ps.ps_ExprContext;
/*
* Check the qual (HAVING clause); if the group does not match, ignore it.
*/
if (ExecQual(aggstate->ss.ps.qual, econtext))
{
/*
* Form and return projection tuple using the aggregate results and
* the representative input tuple.
*/
return ExecProject(aggstate->ss.ps.ps_ProjInfo);
}
else
InstrCountFiltered1(aggstate, 1);
return NULL;
}
/*
* find_unaggregated_cols
* Construct a bitmapset of the column numbers of un-aggregated Vars
* appearing in our targetlist and qual (HAVING clause)
*/
static Bitmapset *
find_unaggregated_cols(AggState *aggstate)
{
Agg *node = (Agg *) aggstate->ss.ps.plan;
Bitmapset *colnos;
colnos = NULL;
(void) find_unaggregated_cols_walker((Node *) node->plan.targetlist,
&colnos);
(void) find_unaggregated_cols_walker((Node *) node->plan.qual,
&colnos);
return colnos;
}
static bool
find_unaggregated_cols_walker(Node *node, Bitmapset **colnos)
{
if (node == NULL)
return false;
if (IsA(node, Var))
{
Var *var = (Var *) node;
/* setrefs.c should have set the varno to OUTER_VAR */
Assert(var->varno == OUTER_VAR);
Assert(var->varlevelsup == 0);
*colnos = bms_add_member(*colnos, var->varattno);
return false;
}
if (IsA(node, Aggref) ||IsA(node, GroupingFunc))
{
/* do not descend into aggregate exprs */
return false;
}
return expression_tree_walker(node, find_unaggregated_cols_walker,
(void *) colnos);
}
/*
* (Re-)initialize the hash table(s) to empty.
*
* To implement hashed aggregation, we need a hashtable that stores a
* representative tuple and an array of AggStatePerGroup structs for each
* distinct set of GROUP BY column values. We compute the hash key from the
* GROUP BY columns. The per-group data is allocated in lookup_hash_entry(),
* for each entry.
*
* We have a separate hashtable and associated perhash data structure for each
* grouping set for which we're doing hashing.
*
* The contents of the hash tables always live in the hashcontext's per-tuple
* memory context (there is only one of these for all tables together, since
* they are all reset at the same time).
*/
static void
build_hash_table(AggState *aggstate)
{
MemoryContext tmpmem = aggstate->tmpcontext->ecxt_per_tuple_memory;
Size additionalsize;
int i;
Assert(aggstate->aggstrategy == AGG_HASHED || aggstate->aggstrategy == AGG_MIXED);
additionalsize = aggstate->numtrans * sizeof(AggStatePerGroupData);
for (i = 0; i < aggstate->num_hashes; ++i)
{
AggStatePerHash perhash = &aggstate->perhash[i];
Assert(perhash->aggnode->numGroups > 0);
if (perhash->hashtable)
ResetTupleHashTable(perhash->hashtable);
else
perhash->hashtable = BuildTupleHashTableExt(&aggstate->ss.ps,
perhash->hashslot->tts_tupleDescriptor,
perhash->numCols,
perhash->hashGrpColIdxHash,
perhash->eqfuncoids,
perhash->hashfunctions,
perhash->aggnode->numGroups,
additionalsize,
aggstate->ss.ps.state->es_query_cxt,
aggstate->hashcontext->ecxt_per_tuple_memory,
tmpmem,
DO_AGGSPLIT_SKIPFINAL(aggstate->aggsplit));
}
}
/*
* Compute columns that actually need to be stored in hashtable entries. The
* incoming tuples from the child plan node will contain grouping columns,
* other columns referenced in our targetlist and qual, columns used to
* compute the aggregate functions, and perhaps just junk columns we don't use
* at all. Only columns of the first two types need to be stored in the
* hashtable, and getting rid of the others can make the table entries
* significantly smaller. The hashtable only contains the relevant columns,
* and is packed/unpacked in lookup_hash_entry() / agg_retrieve_hash_table()
* into the format of the normal input descriptor.
*
* Additional columns, in addition to the columns grouped by, come from two
* sources: Firstly functionally dependent columns that we don't need to group
* by themselves, and secondly ctids for row-marks.
*
* To eliminate duplicates, we build a bitmapset of the needed columns, and
* then build an array of the columns included in the hashtable. Note that
* the array is preserved over ExecReScanAgg, so we allocate it in the
* per-query context (unlike the hash table itself).
*/
static void
find_hash_columns(AggState *aggstate)
{
Bitmapset *base_colnos;
List *outerTlist = outerPlanState(aggstate)->plan->targetlist;
int numHashes = aggstate->num_hashes;
EState *estate = aggstate->ss.ps.state;
int j;
/* Find Vars that will be needed in tlist and qual */
base_colnos = find_unaggregated_cols(aggstate);
for (j = 0; j < numHashes; ++j)
{
AggStatePerHash perhash = &aggstate->perhash[j];
Bitmapset *colnos = bms_copy(base_colnos);
AttrNumber *grpColIdx = perhash->aggnode->grpColIdx;
List *hashTlist = NIL;
TupleDesc hashDesc;
int i;
perhash->largestGrpColIdx = 0;
/*
* If we're doing grouping sets, then some Vars might be referenced in
* tlist/qual for the benefit of other grouping sets, but not needed
* when hashing; i.e. prepare_projection_slot will null them out, so
* there'd be no point storing them. Use prepare_projection_slot's
* logic to determine which.
*/
if (aggstate->phases[0].grouped_cols)
{
Bitmapset *grouped_cols = aggstate->phases[0].grouped_cols[j];
ListCell *lc;
foreach(lc, aggstate->all_grouped_cols)
{
int attnum = lfirst_int(lc);
if (!bms_is_member(attnum, grouped_cols))
colnos = bms_del_member(colnos, attnum);
}
}
/* Add in all the grouping columns */
for (i = 0; i < perhash->numCols; i++)
colnos = bms_add_member(colnos, grpColIdx[i]);
perhash->hashGrpColIdxInput =
palloc(bms_num_members(colnos) * sizeof(AttrNumber));
perhash->hashGrpColIdxHash =
palloc(perhash->numCols * sizeof(AttrNumber));
/*
* First build mapping for columns directly hashed. These are the
* first, because they'll be accessed when computing hash values and
* comparing tuples for exact matches. We also build simple mapping
* for execGrouping, so it knows where to find the to-be-hashed /
* compared columns in the input.
*/
for (i = 0; i < perhash->numCols; i++)
{
perhash->hashGrpColIdxInput[i] = grpColIdx[i];
perhash->hashGrpColIdxHash[i] = i + 1;
perhash->numhashGrpCols++;
/* delete already mapped columns */
bms_del_member(colnos, grpColIdx[i]);
}
/* and add the remaining columns */
while ((i = bms_first_member(colnos)) >= 0)
{
perhash->hashGrpColIdxInput[perhash->numhashGrpCols] = i;
perhash->numhashGrpCols++;
}
/* and build a tuple descriptor for the hashtable */
for (i = 0; i < perhash->numhashGrpCols; i++)
{
int varNumber = perhash->hashGrpColIdxInput[i] - 1;
hashTlist = lappend(hashTlist, list_nth(outerTlist, varNumber));
perhash->largestGrpColIdx =
Max(varNumber + 1, perhash->largestGrpColIdx);
}
hashDesc = ExecTypeFromTL(hashTlist, false);
execTuplesHashPrepare(perhash->numCols,
perhash->aggnode->grpOperators,
&perhash->eqfuncoids,
&perhash->hashfunctions);
perhash->hashslot =
ExecAllocTableSlot(&estate->es_tupleTable, hashDesc);
list_free(hashTlist);
bms_free(colnos);
}
bms_free(base_colnos);
}
/*
* Estimate per-hash-table-entry overhead for the planner.
*
* Note that the estimate does not include space for pass-by-reference
* transition data values, nor for the representative tuple of each group.
* Nor does this account of the target fill-factor and growth policy of the
* hash table.
*/
Size
hash_agg_entry_size(int numAggs)
{
Size entrysize;
/* This must match build_hash_table */
entrysize = sizeof(TupleHashEntryData) +
numAggs * sizeof(AggStatePerGroupData);
entrysize = MAXALIGN(entrysize);
return entrysize;
}
/*
* Find or create a hashtable entry for the tuple group containing the current
* tuple (already set in tmpcontext's outertuple slot), in the current grouping
* set (which the caller must have selected - note that initialize_aggregate
* depends on this).
*
* When called, CurrentMemoryContext should be the per-query context.
*/
static TupleHashEntryData *
lookup_hash_entry(AggState *aggstate)
{
TupleTableSlot *inputslot = aggstate->tmpcontext->ecxt_outertuple;
AggStatePerHash perhash = &aggstate->perhash[aggstate->current_set];
TupleTableSlot *hashslot = perhash->hashslot;
TupleHashEntryData *entry;
bool isnew;
int i;
/* transfer just the needed columns into hashslot */
slot_getsomeattrs(inputslot, perhash->largestGrpColIdx);
ExecClearTuple(hashslot);
for (i = 0; i < perhash->numhashGrpCols; i++)
{
int varNumber = perhash->hashGrpColIdxInput[i] - 1;
hashslot->tts_values[i] = inputslot->tts_values[varNumber];
hashslot->tts_isnull[i] = inputslot->tts_isnull[varNumber];
}
ExecStoreVirtualTuple(hashslot);
/* find or create the hashtable entry using the filtered tuple */
entry = LookupTupleHashEntry(perhash->hashtable, hashslot, &isnew);
if (isnew)
{
AggStatePerGroup pergroup;
int transno;
pergroup = (AggStatePerGroup)
MemoryContextAlloc(perhash->hashtable->tablecxt,
sizeof(AggStatePerGroupData) * aggstate->numtrans);
entry->additional = pergroup;
/*
* Initialize aggregates for new tuple group, lookup_hash_entries()
* already has selected the relevant grouping set.
*/
for (transno = 0; transno < aggstate->numtrans; transno++)
{
AggStatePerTrans pertrans = &aggstate->pertrans[transno];
AggStatePerGroup pergroupstate = &pergroup[transno];
initialize_aggregate(aggstate, pertrans, pergroupstate);
}
}
return entry;
}
/*
* Look up hash entries for the current tuple in all hashed grouping sets,
* returning an array of pergroup pointers suitable for advance_aggregates.
*
* Be aware that lookup_hash_entry can reset the tmpcontext.
*/
static void
lookup_hash_entries(AggState *aggstate)
{
int numHashes = aggstate->num_hashes;
AggStatePerGroup *pergroup = aggstate->hash_pergroup;
int setno;
for (setno = 0; setno < numHashes; setno++)
{
select_current_set(aggstate, setno, true);
pergroup[setno] = lookup_hash_entry(aggstate)->additional;
}
}
/*
* ExecAgg -
*
* ExecAgg receives tuples from its outer subplan and aggregates over
* the appropriate attribute for each aggregate function use (Aggref
* node) appearing in the targetlist or qual of the node. The number
* of tuples to aggregate over depends on whether grouped or plain
* aggregation is selected. In grouped aggregation, we produce a result
* row for each group; in plain aggregation there's a single result row
* for the whole query. In either case, the value of each aggregate is
* stored in the expression context to be used when ExecProject evaluates
* the result tuple.
*/
static TupleTableSlot *
ExecAgg(PlanState *pstate)
{
AggState *node = castNode(AggState, pstate);
TupleTableSlot *result = NULL;
CHECK_FOR_INTERRUPTS();
if (!node->agg_done)
{
/* Dispatch based on strategy */
switch (node->phase->aggstrategy)
{
case AGG_HASHED:
if (!node->table_filled)
agg_fill_hash_table(node);
/* FALLTHROUGH */
case AGG_MIXED:
result = agg_retrieve_hash_table(node);
break;
case AGG_PLAIN:
case AGG_SORTED:
result = agg_retrieve_direct(node);
break;
}
if (!TupIsNull(result))
return result;
}
return NULL;
}
/*
* ExecAgg for non-hashed case
*/
static TupleTableSlot *
agg_retrieve_direct(AggState *aggstate)
{
Agg *node = aggstate->phase->aggnode;
ExprContext *econtext;
ExprContext *tmpcontext;
AggStatePerAgg peragg;
AggStatePerGroup *pergroups;
TupleTableSlot *outerslot;
TupleTableSlot *firstSlot;
TupleTableSlot *result;
bool hasGroupingSets = aggstate->phase->numsets > 0;
int numGroupingSets = Max(aggstate->phase->numsets, 1);
int currentSet;
int nextSetSize;
int numReset;
int i;
/*
* get state info from node
*
* econtext is the per-output-tuple expression context
*
* tmpcontext is the per-input-tuple expression context
*/
econtext = aggstate->ss.ps.ps_ExprContext;
tmpcontext = aggstate->tmpcontext;
peragg = aggstate->peragg;
pergroups = aggstate->pergroups;
firstSlot = aggstate->ss.ss_ScanTupleSlot;
/*
* We loop retrieving groups until we find one matching
* aggstate->ss.ps.qual
*
* For grouping sets, we have the invariant that aggstate->projected_set
* is either -1 (initial call) or the index (starting from 0) in
* gset_lengths for the group we just completed (either by projecting a
* row or by discarding it in the qual).
*/
while (!aggstate->agg_done)
{
/*
* Clear the per-output-tuple context for each group, as well as
* aggcontext (which contains any pass-by-ref transvalues of the old
* group). Some aggregate functions store working state in child
* contexts; those now get reset automatically without us needing to
* do anything special.
*
* We use ReScanExprContext not just ResetExprContext because we want
* any registered shutdown callbacks to be called. That allows
* aggregate functions to ensure they've cleaned up any non-memory
* resources.
*/
ReScanExprContext(econtext);
/*
* Determine how many grouping sets need to be reset at this boundary.
*/
if (aggstate->projected_set >= 0 &&
aggstate->projected_set < numGroupingSets)
numReset = aggstate->projected_set + 1;
else
numReset = numGroupingSets;
/*
* numReset can change on a phase boundary, but that's OK; we want to
* reset the contexts used in _this_ phase, and later, after possibly
* changing phase, initialize the right number of aggregates for the
* _new_ phase.
*/
for (i = 0; i < numReset; i++)
{
ReScanExprContext(aggstate->aggcontexts[i]);
}
/*
* Check if input is complete and there are no more groups to project
* in this phase; move to next phase or mark as done.
*/
if (aggstate->input_done == true &&
aggstate->projected_set >= (numGroupingSets - 1))
{
if (aggstate->current_phase < aggstate->numphases - 1)
{
initialize_phase(aggstate, aggstate->current_phase + 1);
aggstate->input_done = false;
aggstate->projected_set = -1;
numGroupingSets = Max(aggstate->phase->numsets, 1);
node = aggstate->phase->aggnode;
numReset = numGroupingSets;
}
else if (aggstate->aggstrategy == AGG_MIXED)
{
/*
* Mixed mode; we've output all the grouped stuff and have
* full hashtables, so switch to outputting those.
*/
initialize_phase(aggstate, 0);
aggstate->table_filled = true;
ResetTupleHashIterator(aggstate->perhash[0].hashtable,
&aggstate->perhash[0].hashiter);
select_current_set(aggstate, 0, true);
return agg_retrieve_hash_table(aggstate);
}
else
{
aggstate->agg_done = true;
break;
}
}
/*
* Get the number of columns in the next grouping set after the last
* projected one (if any). This is the number of columns to compare to
* see if we reached the boundary of that set too.
*/
if (aggstate->projected_set >= 0 &&
aggstate->projected_set < (numGroupingSets - 1))
nextSetSize = aggstate->phase->gset_lengths[aggstate->projected_set + 1];
else
nextSetSize = 0;
/*----------
* If a subgroup for the current grouping set is present, project it.
*
* We have a new group if:
* - we're out of input but haven't projected all grouping sets
* (checked above)
* OR
* - we already projected a row that wasn't from the last grouping
* set
* AND
* - the next grouping set has at least one grouping column (since
* empty grouping sets project only once input is exhausted)
* AND
* - the previous and pending rows differ on the grouping columns
* of the next grouping set
*----------
*/
tmpcontext->ecxt_innertuple = econtext->ecxt_outertuple;
if (aggstate->input_done ||
(node->aggstrategy != AGG_PLAIN &&
aggstate->projected_set != -1 &&
aggstate->projected_set < (numGroupingSets - 1) &&
nextSetSize > 0 &&
!ExecQualAndReset(aggstate->phase->eqfunctions[nextSetSize - 1],
tmpcontext)))
{
aggstate->projected_set += 1;
Assert(aggstate->projected_set < numGroupingSets);
Assert(nextSetSize > 0 || aggstate->input_done);
}
else
{
/*
* We no longer care what group we just projected, the next
* projection will always be the first (or only) grouping set
* (unless the input proves to be empty).
*/
aggstate->projected_set = 0;
/*
* If we don't already have the first tuple of the new group,
* fetch it from the outer plan.
*/
if (aggstate->grp_firstTuple == NULL)
{
outerslot = fetch_input_tuple(aggstate);
if (!TupIsNull(outerslot))
{
/*
* Make a copy of the first input tuple; we will use this
* for comparisons (in group mode) and for projection.
*/
aggstate->grp_firstTuple = ExecCopySlotTuple(outerslot);
}
else
{
/* outer plan produced no tuples at all */
if (hasGroupingSets)
{
/*
* If there was no input at all, we need to project
* rows only if there are grouping sets of size 0.
* Note that this implies that there can't be any
* references to ungrouped Vars, which would otherwise
* cause issues with the empty output slot.
*
* XXX: This is no longer true, we currently deal with
* this in finalize_aggregates().
*/
aggstate->input_done = true;
while (aggstate->phase->gset_lengths[aggstate->projected_set] > 0)
{
aggstate->projected_set += 1;
if (aggstate->projected_set >= numGroupingSets)
{
/*
* We can't set agg_done here because we might
* have more phases to do, even though the
* input is empty. So we need to restart the
* whole outer loop.
*/
break;
}
}
if (aggstate->projected_set >= numGroupingSets)
continue;
}
else
{
aggstate->agg_done = true;
/* If we are grouping, we should produce no tuples too */
if (node->aggstrategy != AGG_PLAIN)
return NULL;
}
}
}
/*
* Initialize working state for a new input tuple group.
*/
initialize_aggregates(aggstate, pergroups, numReset);
if (aggstate->grp_firstTuple != NULL)
{
/*
* Store the copied first input tuple in the tuple table slot
* reserved for it. The tuple will be deleted when it is
* cleared from the slot.
*/
ExecStoreTuple(aggstate->grp_firstTuple,
firstSlot,
InvalidBuffer,
true);
aggstate->grp_firstTuple = NULL; /* don't keep two pointers */
/* set up for first advance_aggregates call */
tmpcontext->ecxt_outertuple = firstSlot;
/*
* Process each outer-plan tuple, and then fetch the next one,
* until we exhaust the outer plan or cross a group boundary.
*/
for (;;)
{
/*
* During phase 1 only of a mixed agg, we need to update
* hashtables as well in advance_aggregates.
*/
if (aggstate->aggstrategy == AGG_MIXED &&
aggstate->current_phase == 1)
{
lookup_hash_entries(aggstate);
}
/* Advance the aggregates (or combine functions) */
advance_aggregates(aggstate);
/* Reset per-input-tuple context after each tuple */
ResetExprContext(tmpcontext);
outerslot = fetch_input_tuple(aggstate);
if (TupIsNull(outerslot))
{
/* no more outer-plan tuples available */
if (hasGroupingSets)
{
aggstate->input_done = true;
break;
}
else
{
aggstate->agg_done = true;
break;
}
}
/* set up for next advance_aggregates call */
tmpcontext->ecxt_outertuple = outerslot;
/*
* If we are grouping, check whether we've crossed a group
* boundary.
*/
if (node->aggstrategy != AGG_PLAIN)
{
tmpcontext->ecxt_innertuple = firstSlot;
if (!ExecQual(aggstate->phase->eqfunctions[node->numCols - 1],
tmpcontext))
{
aggstate->grp_firstTuple = ExecCopySlotTuple(outerslot);
break;
}
}
}
}
/*
* Use the representative input tuple for any references to
* non-aggregated input columns in aggregate direct args, the node
* qual, and the tlist. (If we are not grouping, and there are no
* input rows at all, we will come here with an empty firstSlot
* ... but if not grouping, there can't be any references to
* non-aggregated input columns, so no problem.)
*/
econtext->ecxt_outertuple = firstSlot;
}
Assert(aggstate->projected_set >= 0);
currentSet = aggstate->projected_set;
prepare_projection_slot(aggstate, econtext->ecxt_outertuple, currentSet);
select_current_set(aggstate, currentSet, false);
finalize_aggregates(aggstate,
peragg,
pergroups[currentSet]);
/*
* If there's no row to project right now, we must continue rather
* than returning a null since there might be more groups.
*/
result = project_aggregates(aggstate);
if (result)
return result;
}
/* No more groups */
return NULL;
}
/*
* ExecAgg for hashed case: read input and build hash table
*/
static void
agg_fill_hash_table(AggState *aggstate)
{
TupleTableSlot *outerslot;
ExprContext *tmpcontext = aggstate->tmpcontext;
/*
* Process each outer-plan tuple, and then fetch the next one, until we
* exhaust the outer plan.
*/
for (;;)
{
outerslot = fetch_input_tuple(aggstate);
if (TupIsNull(outerslot))
break;
/* set up for lookup_hash_entries and advance_aggregates */
tmpcontext->ecxt_outertuple = outerslot;
/* Find or build hashtable entries */
lookup_hash_entries(aggstate);
/* Advance the aggregates (or combine functions) */
advance_aggregates(aggstate);
/*
* Reset per-input-tuple context after each tuple, but note that the
* hash lookups do this too
*/
ResetExprContext(aggstate->tmpcontext);
}
aggstate->table_filled = true;
/* Initialize to walk the first hash table */
select_current_set(aggstate, 0, true);
ResetTupleHashIterator(aggstate->perhash[0].hashtable,
&aggstate->perhash[0].hashiter);
}
/*
* ExecAgg for hashed case: retrieving groups from hash table
*/
static TupleTableSlot *
agg_retrieve_hash_table(AggState *aggstate)
{
ExprContext *econtext;
AggStatePerAgg peragg;
AggStatePerGroup pergroup;
TupleHashEntryData *entry;
TupleTableSlot *firstSlot;
TupleTableSlot *result;
AggStatePerHash perhash;
/*
* get state info from node.
*
* econtext is the per-output-tuple expression context.
*/
econtext = aggstate->ss.ps.ps_ExprContext;
peragg = aggstate->peragg;
firstSlot = aggstate->ss.ss_ScanTupleSlot;
/*
* Note that perhash (and therefore anything accessed through it) can
* change inside the loop, as we change between grouping sets.
*/
perhash = &aggstate->perhash[aggstate->current_set];
/*
* We loop retrieving groups until we find one satisfying
* aggstate->ss.ps.qual
*/
while (!aggstate->agg_done)
{
TupleTableSlot *hashslot = perhash->hashslot;
int i;
CHECK_FOR_INTERRUPTS();
/*
* Find the next entry in the hash table
*/
entry = ScanTupleHashTable(perhash->hashtable, &perhash->hashiter);
if (entry == NULL)
{
int nextset = aggstate->current_set + 1;
if (nextset < aggstate->num_hashes)
{
/*
* Switch to next grouping set, reinitialize, and restart the
* loop.
*/
select_current_set(aggstate, nextset, true);
perhash = &aggstate->perhash[aggstate->current_set];
ResetTupleHashIterator(perhash->hashtable, &perhash->hashiter);
continue;
}
else
{
/* No more hashtables, so done */
aggstate->agg_done = true;
return NULL;
}
}
/*
* Clear the per-output-tuple context for each group
*
* We intentionally don't use ReScanExprContext here; if any aggs have
* registered shutdown callbacks, they mustn't be called yet, since we
* might not be done with that agg.
*/
ResetExprContext(econtext);
/*
* Transform representative tuple back into one with the right
* columns.
*/
ExecStoreMinimalTuple(entry->firstTuple, hashslot, false);
slot_getallattrs(hashslot);
ExecClearTuple(firstSlot);
memset(firstSlot->tts_isnull, true,
firstSlot->tts_tupleDescriptor->natts * sizeof(bool));
for (i = 0; i < perhash->numhashGrpCols; i++)
{
int varNumber = perhash->hashGrpColIdxInput[i] - 1;
firstSlot->tts_values[varNumber] = hashslot->tts_values[i];
firstSlot->tts_isnull[varNumber] = hashslot->tts_isnull[i];
}
ExecStoreVirtualTuple(firstSlot);
pergroup = (AggStatePerGroup) entry->additional;
/*
* Use the representative input tuple for any references to
* non-aggregated input columns in the qual and tlist.
*/
econtext->ecxt_outertuple = firstSlot;
prepare_projection_slot(aggstate,
econtext->ecxt_outertuple,
aggstate->current_set);
finalize_aggregates(aggstate, peragg, pergroup);
result = project_aggregates(aggstate);
if (result)
return result;
}
/* No more groups */
return NULL;
}
/* -----------------
* ExecInitAgg
*
* Creates the run-time information for the agg node produced by the
* planner and initializes its outer subtree.
*
* -----------------
*/
AggState *
ExecInitAgg(Agg *node, EState *estate, int eflags)
{
AggState *aggstate;
AggStatePerAgg peraggs;
AggStatePerTrans pertransstates;
AggStatePerGroup *pergroups;
Plan *outerPlan;
ExprContext *econtext;
TupleDesc scanDesc;
int numaggs,
transno,
aggno;
int phase;
int phaseidx;
ListCell *l;
Bitmapset *all_grouped_cols = NULL;
int numGroupingSets = 1;
int numPhases;
int numHashes;
int i = 0;
int j = 0;
bool use_hashing = (node->aggstrategy == AGG_HASHED ||
node->aggstrategy == AGG_MIXED);
/* check for unsupported flags */
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
/*
* create state structure
*/
aggstate = makeNode(AggState);
aggstate->ss.ps.plan = (Plan *) node;
aggstate->ss.ps.state = estate;
aggstate->ss.ps.ExecProcNode = ExecAgg;
aggstate->aggs = NIL;
aggstate->numaggs = 0;
aggstate->numtrans = 0;
aggstate->aggstrategy = node->aggstrategy;
aggstate->aggsplit = node->aggsplit;
aggstate->maxsets = 0;
aggstate->projected_set = -1;
aggstate->current_set = 0;
aggstate->peragg = NULL;
aggstate->pertrans = NULL;
aggstate->curperagg = NULL;
aggstate->curpertrans = NULL;
aggstate->input_done = false;
aggstate->agg_done = false;
aggstate->pergroups = NULL;
aggstate->grp_firstTuple = NULL;
aggstate->sort_in = NULL;
aggstate->sort_out = NULL;
/*
* phases[0] always exists, but is dummy in sorted/plain mode
*/
numPhases = (use_hashing ? 1 : 2);
numHashes = (use_hashing ? 1 : 0);
/*
* Calculate the maximum number of grouping sets in any phase; this
* determines the size of some allocations. Also calculate the number of
* phases, since all hashed/mixed nodes contribute to only a single phase.
*/
if (node->groupingSets)
{
numGroupingSets = list_length(node->groupingSets);
foreach(l, node->chain)
{
Agg *agg = lfirst(l);
numGroupingSets = Max(numGroupingSets,
list_length(agg->groupingSets));
/*
* additional AGG_HASHED aggs become part of phase 0, but all
* others add an extra phase.
*/
if (agg->aggstrategy != AGG_HASHED)
++numPhases;
else
++numHashes;
}
}
aggstate->maxsets = numGroupingSets;
aggstate->numphases = numPhases;
aggstate->aggcontexts = (ExprContext **)
palloc0(sizeof(ExprContext *) * numGroupingSets);
/*
* Create expression contexts. We need three or more, one for
* per-input-tuple processing, one for per-output-tuple processing, one
* for all the hashtables, and one for each grouping set. The per-tuple
* memory context of the per-grouping-set ExprContexts (aggcontexts)
* replaces the standalone memory context formerly used to hold transition
* values. We cheat a little by using ExecAssignExprContext() to build
* all of them.
*
* NOTE: the details of what is stored in aggcontexts and what is stored
* in the regular per-query memory context are driven by a simple
* decision: we want to reset the aggcontext at group boundaries (if not
* hashing) and in ExecReScanAgg to recover no-longer-wanted space.
*/
ExecAssignExprContext(estate, &aggstate->ss.ps);
aggstate->tmpcontext = aggstate->ss.ps.ps_ExprContext;
for (i = 0; i < numGroupingSets; ++i)
{
ExecAssignExprContext(estate, &aggstate->ss.ps);
aggstate->aggcontexts[i] = aggstate->ss.ps.ps_ExprContext;
}
if (use_hashing)
{
ExecAssignExprContext(estate, &aggstate->ss.ps);
aggstate->hashcontext = aggstate->ss.ps.ps_ExprContext;
}
ExecAssignExprContext(estate, &aggstate->ss.ps);
/*
* Initialize child nodes.
*
* If we are doing a hashed aggregation then the child plan does not need
* to handle REWIND efficiently; see ExecReScanAgg.
*/
if (node->aggstrategy == AGG_HASHED)
eflags &= ~EXEC_FLAG_REWIND;
outerPlan = outerPlan(node);
outerPlanState(aggstate) = ExecInitNode(outerPlan, estate, eflags);
/*
* initialize source tuple type.
*/
ExecCreateScanSlotFromOuterPlan(estate, &aggstate->ss);
scanDesc = aggstate->ss.ss_ScanTupleSlot->tts_tupleDescriptor;
if (node->chain)
aggstate->sort_slot = ExecInitExtraTupleSlot(estate, scanDesc);
/*
* Initialize result type, slot and projection.
*/
ExecInitResultTupleSlotTL(estate, &aggstate->ss.ps);
ExecAssignProjectionInfo(&aggstate->ss.ps, NULL);
/*
* initialize child expressions
*
* We expect the parser to have checked that no aggs contain other agg
* calls in their arguments (and just to be sure, we verify it again while
* initializing the plan node). This would make no sense under SQL
* semantics, and it's forbidden by the spec. Because it is true, we
* don't need to worry about evaluating the aggs in any particular order.
*
* Note: execExpr.c finds Aggrefs for us, and adds their AggrefExprState
* nodes to aggstate->aggs. Aggrefs in the qual are found here; Aggrefs
* in the targetlist are found during ExecAssignProjectionInfo, below.
*/
aggstate->ss.ps.qual =
ExecInitQual(node->plan.qual, (PlanState *) aggstate);
/*
* We should now have found all Aggrefs in the targetlist and quals.
*/
numaggs = aggstate->numaggs;
Assert(numaggs == list_length(aggstate->aggs));
/*
* For each phase, prepare grouping set data and fmgr lookup data for
* compare functions. Accumulate all_grouped_cols in passing.
*/
aggstate->phases = palloc0(numPhases * sizeof(AggStatePerPhaseData));
aggstate->num_hashes = numHashes;
if (numHashes)
{
aggstate->perhash = palloc0(sizeof(AggStatePerHashData) * numHashes);
aggstate->phases[0].numsets = 0;
aggstate->phases[0].gset_lengths = palloc(numHashes * sizeof(int));
aggstate->phases[0].grouped_cols = palloc(numHashes * sizeof(Bitmapset *));
}
phase = 0;
for (phaseidx = 0; phaseidx <= list_length(node->chain); ++phaseidx)
{
Agg *aggnode;
Sort *sortnode;
if (phaseidx > 0)
{
aggnode = list_nth_node(Agg, node->chain, phaseidx - 1);
sortnode = castNode(Sort, aggnode->plan.lefttree);
}
else
{
aggnode = node;
sortnode = NULL;
}
Assert(phase <= 1 || sortnode);
if (aggnode->aggstrategy == AGG_HASHED
|| aggnode->aggstrategy == AGG_MIXED)
{
AggStatePerPhase phasedata = &aggstate->phases[0];
AggStatePerHash perhash;
Bitmapset *cols = NULL;
Assert(phase == 0);
i = phasedata->numsets++;
perhash = &aggstate->perhash[i];
/* phase 0 always points to the "real" Agg in the hash case */
phasedata->aggnode = node;
phasedata->aggstrategy = node->aggstrategy;
/* but the actual Agg node representing this hash is saved here */
perhash->aggnode = aggnode;
phasedata->gset_lengths[i] = perhash->numCols = aggnode->numCols;
for (j = 0; j < aggnode->numCols; ++j)
cols = bms_add_member(cols, aggnode->grpColIdx[j]);
phasedata->grouped_cols[i] = cols;
all_grouped_cols = bms_add_members(all_grouped_cols, cols);
continue;
}
else
{
AggStatePerPhase phasedata = &aggstate->phases[++phase];
int num_sets;
phasedata->numsets = num_sets = list_length(aggnode->groupingSets);
if (num_sets)
{
phasedata->gset_lengths = palloc(num_sets * sizeof(int));
phasedata->grouped_cols = palloc(num_sets * sizeof(Bitmapset *));
i = 0;
foreach(l, aggnode->groupingSets)
{
int current_length = list_length(lfirst(l));
Bitmapset *cols = NULL;
/* planner forces this to be correct */
for (j = 0; j < current_length; ++j)
cols = bms_add_member(cols, aggnode->grpColIdx[j]);
phasedata->grouped_cols[i] = cols;
phasedata->gset_lengths[i] = current_length;
++i;
}
all_grouped_cols = bms_add_members(all_grouped_cols,
phasedata->grouped_cols[0]);
}
else
{
Assert(phaseidx == 0);
phasedata->gset_lengths = NULL;
phasedata->grouped_cols = NULL;
}
/*
* If we are grouping, precompute fmgr lookup data for inner loop.
*/
if (aggnode->aggstrategy == AGG_SORTED)
{
int i = 0;
Assert(aggnode->numCols > 0);
/*
* Build a separate function for each subset of columns that
* need to be compared.
*/
phasedata->eqfunctions =
(ExprState **) palloc0(aggnode->numCols * sizeof(ExprState *));
/* for each grouping set */
for (i = 0; i < phasedata->numsets; i++)
{
int length = phasedata->gset_lengths[i];
if (phasedata->eqfunctions[length - 1] != NULL)
continue;
phasedata->eqfunctions[length - 1] =
execTuplesMatchPrepare(scanDesc,
length,
aggnode->grpColIdx,
aggnode->grpOperators,
(PlanState *) aggstate);
}
/* and for all grouped columns, unless already computed */
if (phasedata->eqfunctions[aggnode->numCols - 1] == NULL)
{
phasedata->eqfunctions[aggnode->numCols - 1] =
execTuplesMatchPrepare(scanDesc,
aggnode->numCols,
aggnode->grpColIdx,
aggnode->grpOperators,
(PlanState *) aggstate);
}
}
phasedata->aggnode = aggnode;
phasedata->aggstrategy = aggnode->aggstrategy;
phasedata->sortnode = sortnode;
}
}
/*
* Convert all_grouped_cols to a descending-order list.
*/
i = -1;
while ((i = bms_next_member(all_grouped_cols, i)) >= 0)
aggstate->all_grouped_cols = lcons_int(i, aggstate->all_grouped_cols);
/*
* Set up aggregate-result storage in the output expr context, and also
* allocate my private per-agg working storage
*/
econtext = aggstate->ss.ps.ps_ExprContext;
econtext->ecxt_aggvalues = (Datum *) palloc0(sizeof(Datum) * numaggs);
econtext->ecxt_aggnulls = (bool *) palloc0(sizeof(bool) * numaggs);
peraggs = (AggStatePerAgg) palloc0(sizeof(AggStatePerAggData) * numaggs);
pertransstates = (AggStatePerTrans) palloc0(sizeof(AggStatePerTransData) * numaggs);
aggstate->peragg = peraggs;
aggstate->pertrans = pertransstates;
aggstate->all_pergroups =
(AggStatePerGroup *) palloc0(sizeof(AggStatePerGroup)
* (numGroupingSets + numHashes));
pergroups = aggstate->all_pergroups;
if (node->aggstrategy != AGG_HASHED)
{
for (i = 0; i < numGroupingSets; i++)
{
pergroups[i] = (AggStatePerGroup) palloc0(sizeof(AggStatePerGroupData)
* numaggs);
}
aggstate->pergroups = pergroups;
pergroups += numGroupingSets;
}
/*
* Hashing can only appear in the initial phase.
*/
if (use_hashing)
{
/* this is an array of pointers, not structures */
aggstate->hash_pergroup = pergroups;
find_hash_columns(aggstate);
build_hash_table(aggstate);
aggstate->table_filled = false;
}
/*
* Initialize current phase-dependent values to initial phase. The initial
* phase is 1 (first sort pass) for all strategies that use sorting (if
* hashing is being done too, then phase 0 is processed last); but if only
* hashing is being done, then phase 0 is all there is.
*/
if (node->aggstrategy == AGG_HASHED)
{
aggstate->current_phase = 0;
initialize_phase(aggstate, 0);
select_current_set(aggstate, 0, true);
}
else
{
aggstate->current_phase = 1;
initialize_phase(aggstate, 1);
select_current_set(aggstate, 0, false);
}
/* -----------------
* Perform lookups of aggregate function info, and initialize the
* unchanging fields of the per-agg and per-trans data.
*
* We try to optimize by detecting duplicate aggregate functions so that
* their state and final values are re-used, rather than needlessly being
* re-calculated independently. We also detect aggregates that are not
* the same, but which can share the same transition state.
*
* Scenarios:
*
* 1. Identical aggregate function calls appear in the query:
*
* SELECT SUM(x) FROM ... HAVING SUM(x) > 0
*
* Since these aggregates are identical, we only need to calculate
* the value once. Both aggregates will share the same 'aggno' value.
*
* 2. Two different aggregate functions appear in the query, but the
* aggregates have the same arguments, transition functions and
* initial values (and, presumably, different final functions):
*
* SELECT AVG(x), STDDEV(x) FROM ...
*
* In this case we must create a new peragg for the varying aggregate,
* and we need to call the final functions separately, but we need
* only run the transition function once. (This requires that the
* final functions be nondestructive of the transition state, but
* that's required anyway for other reasons.)
*
* For either of these optimizations to be valid, all aggregate properties
* used in the transition phase must be the same, including any modifiers
* such as ORDER BY, DISTINCT and FILTER, and the arguments mustn't
* contain any volatile functions.
* -----------------
*/
aggno = -1;
transno = -1;
foreach(l, aggstate->aggs)
{
AggrefExprState *aggrefstate = (AggrefExprState *) lfirst(l);
Aggref *aggref = aggrefstate->aggref;
AggStatePerAgg peragg;
AggStatePerTrans pertrans;
int existing_aggno;
int existing_transno;
List *same_input_transnos;
Oid inputTypes[FUNC_MAX_ARGS];
int numArguments;
int numDirectArgs;
HeapTuple aggTuple;
Form_pg_aggregate aggform;
AclResult aclresult;
Oid transfn_oid,
finalfn_oid;
bool shareable;
Oid serialfn_oid,
deserialfn_oid;
Expr *finalfnexpr;
Oid aggtranstype;
Datum textInitVal;
Datum initValue;
bool initValueIsNull;
/* Planner should have assigned aggregate to correct level */
Assert(aggref->agglevelsup == 0);
/* ... and the split mode should match */
Assert(aggref->aggsplit == aggstate->aggsplit);
/* 1. Check for already processed aggs which can be re-used */
existing_aggno = find_compatible_peragg(aggref, aggstate, aggno,
&same_input_transnos);
if (existing_aggno != -1)
{
/*
* Existing compatible agg found. so just point the Aggref to the
* same per-agg struct.
*/
aggrefstate->aggno = existing_aggno;
continue;
}
/* Mark Aggref state node with assigned index in the result array */
peragg = &peraggs[++aggno];
peragg->aggref = aggref;
aggrefstate->aggno = aggno;
/* Fetch the pg_aggregate row */
aggTuple = SearchSysCache1(AGGFNOID,
ObjectIdGetDatum(aggref->aggfnoid));
if (!HeapTupleIsValid(aggTuple))
elog(ERROR, "cache lookup failed for aggregate %u",
aggref->aggfnoid);
aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
/* Check permission to call aggregate function */
aclresult = pg_proc_aclcheck(aggref->aggfnoid, GetUserId(),
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_AGGREGATE,
get_func_name(aggref->aggfnoid));
InvokeFunctionExecuteHook(aggref->aggfnoid);
/* planner recorded transition state type in the Aggref itself */
aggtranstype = aggref->aggtranstype;
Assert(OidIsValid(aggtranstype));
/*
* If this aggregation is performing state combines, then instead of
* using the transition function, we'll use the combine function
*/
if (DO_AGGSPLIT_COMBINE(aggstate->aggsplit))
{
transfn_oid = aggform->aggcombinefn;
/* If not set then the planner messed up */
if (!OidIsValid(transfn_oid))
elog(ERROR, "combinefn not set for aggregate function");
}
else
transfn_oid = aggform->aggtransfn;
/* Final function only required if we're finalizing the aggregates */
if (DO_AGGSPLIT_SKIPFINAL(aggstate->aggsplit))
peragg->finalfn_oid = finalfn_oid = InvalidOid;
else
peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
/*
* If finalfn is marked read-write, we can't share transition states;
* but it is okay to share states for AGGMODIFY_SHAREABLE aggs. Also,
* if we're not executing the finalfn here, we can share regardless.
*/
shareable = (aggform->aggfinalmodify != AGGMODIFY_READ_WRITE) ||
(finalfn_oid == InvalidOid);
peragg->shareable = shareable;
serialfn_oid = InvalidOid;
deserialfn_oid = InvalidOid;
/*
* Check if serialization/deserialization is required. We only do it
* for aggregates that have transtype INTERNAL.
*/
if (aggtranstype == INTERNALOID)
{
/*
* The planner should only have generated a serialize agg node if
* every aggregate with an INTERNAL state has a serialization
* function. Verify that.
*/
if (DO_AGGSPLIT_SERIALIZE(aggstate->aggsplit))
{
/* serialization only valid when not running finalfn */
Assert(DO_AGGSPLIT_SKIPFINAL(aggstate->aggsplit));
if (!OidIsValid(aggform->aggserialfn))
elog(ERROR, "serialfunc not provided for serialization aggregation");
serialfn_oid = aggform->aggserialfn;
}
/* Likewise for deserialization functions */
if (DO_AGGSPLIT_DESERIALIZE(aggstate->aggsplit))
{
/* deserialization only valid when combining states */
Assert(DO_AGGSPLIT_COMBINE(aggstate->aggsplit));
if (!OidIsValid(aggform->aggdeserialfn))
elog(ERROR, "deserialfunc not provided for deserialization aggregation");
deserialfn_oid = aggform->aggdeserialfn;
}
}
/* Check that aggregate owner has permission to call component fns */
{
HeapTuple procTuple;
Oid aggOwner;
procTuple = SearchSysCache1(PROCOID,
ObjectIdGetDatum(aggref->aggfnoid));
if (!HeapTupleIsValid(procTuple))
elog(ERROR, "cache lookup failed for function %u",
aggref->aggfnoid);
aggOwner = ((Form_pg_proc) GETSTRUCT(procTuple))->proowner;
ReleaseSysCache(procTuple);
aclresult = pg_proc_aclcheck(transfn_oid, aggOwner,
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_FUNCTION,
get_func_name(transfn_oid));
InvokeFunctionExecuteHook(transfn_oid);
if (OidIsValid(finalfn_oid))
{
aclresult = pg_proc_aclcheck(finalfn_oid, aggOwner,
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_FUNCTION,
get_func_name(finalfn_oid));
InvokeFunctionExecuteHook(finalfn_oid);
}
if (OidIsValid(serialfn_oid))
{
aclresult = pg_proc_aclcheck(serialfn_oid, aggOwner,
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_FUNCTION,
get_func_name(serialfn_oid));
InvokeFunctionExecuteHook(serialfn_oid);
}
if (OidIsValid(deserialfn_oid))
{
aclresult = pg_proc_aclcheck(deserialfn_oid, aggOwner,
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_FUNCTION,
get_func_name(deserialfn_oid));
InvokeFunctionExecuteHook(deserialfn_oid);
}
}
/*
* Get actual datatypes of the (nominal) aggregate inputs. These
* could be different from the agg's declared input types, when the
* agg accepts ANY or a polymorphic type.
*/
numArguments = get_aggregate_argtypes(aggref, inputTypes);
/* Count the "direct" arguments, if any */
numDirectArgs = list_length(aggref->aggdirectargs);
/* Detect how many arguments to pass to the finalfn */
if (aggform->aggfinalextra)
peragg->numFinalArgs = numArguments + 1;
else
peragg->numFinalArgs = numDirectArgs + 1;
/* Initialize any direct-argument expressions */
peragg->aggdirectargs = ExecInitExprList(aggref->aggdirectargs,
(PlanState *) aggstate);
/*
* build expression trees using actual argument & result types for the
* finalfn, if it exists and is required.
*/
if (OidIsValid(finalfn_oid))
{
build_aggregate_finalfn_expr(inputTypes,
peragg->numFinalArgs,
aggtranstype,
aggref->aggtype,
aggref->inputcollid,
finalfn_oid,
&finalfnexpr);
fmgr_info(finalfn_oid, &peragg->finalfn);
fmgr_info_set_expr((Node *) finalfnexpr, &peragg->finalfn);
}
/* get info about the output value's datatype */
get_typlenbyval(aggref->aggtype,
&peragg->resulttypeLen,
&peragg->resulttypeByVal);
/*
* initval is potentially null, so don't try to access it as a struct
* field. Must do it the hard way with SysCacheGetAttr.
*/
textInitVal = SysCacheGetAttr(AGGFNOID, aggTuple,
Anum_pg_aggregate_agginitval,
&initValueIsNull);
if (initValueIsNull)
initValue = (Datum) 0;
else
initValue = GetAggInitVal(textInitVal, aggtranstype);
/*
* 2. Build working state for invoking the transition function, or
* look up previously initialized working state, if we can share it.
*
* find_compatible_peragg() already collected a list of shareable
* per-Trans's with the same inputs. Check if any of them have the
* same transition function and initial value.
*/
existing_transno = find_compatible_pertrans(aggstate, aggref,
shareable,
transfn_oid, aggtranstype,
serialfn_oid, deserialfn_oid,
initValue, initValueIsNull,
same_input_transnos);
if (existing_transno != -1)
{
/*
* Existing compatible trans found, so just point the 'peragg' to
* the same per-trans struct, and mark the trans state as shared.
*/
pertrans = &pertransstates[existing_transno];
pertrans->aggshared = true;
peragg->transno = existing_transno;
}
else
{
pertrans = &pertransstates[++transno];
build_pertrans_for_aggref(pertrans, aggstate, estate,
aggref, transfn_oid, aggtranstype,
serialfn_oid, deserialfn_oid,
initValue, initValueIsNull,
inputTypes, numArguments);
peragg->transno = transno;
}
ReleaseSysCache(aggTuple);
}
/*
* Update aggstate->numaggs to be the number of unique aggregates found.
* Also set numstates to the number of unique transition states found.
*/
aggstate->numaggs = aggno + 1;
aggstate->numtrans = transno + 1;
/*
* Last, check whether any more aggregates got added onto the node while
* we processed the expressions for the aggregate arguments (including not
* only the regular arguments and FILTER expressions handled immediately
* above, but any direct arguments we might've handled earlier). If so,
* we have nested aggregate functions, which is semantically nonsensical,
* so complain. (This should have been caught by the parser, so we don't
* need to work hard on a helpful error message; but we defend against it
* here anyway, just to be sure.)
*/
if (numaggs != list_length(aggstate->aggs))
ereport(ERROR,
(errcode(ERRCODE_GROUPING_ERROR),
errmsg("aggregate function calls cannot be nested")));
/*
* Build expressions doing all the transition work at once. We build a
* different one for each phase, as the number of transition function
* invocation can differ between phases. Note this'll work both for
* transition and combination functions (although there'll only be one
* phase in the latter case).
*/
for (phaseidx = 0; phaseidx < aggstate->numphases; phaseidx++)
{
AggStatePerPhase phase = &aggstate->phases[phaseidx];
bool dohash = false;
bool dosort = false;
/* phase 0 doesn't necessarily exist */
if (!phase->aggnode)
continue;
if (aggstate->aggstrategy == AGG_MIXED && phaseidx == 1)
{
/*
* Phase one, and only phase one, in a mixed agg performs both
* sorting and aggregation.
*/
dohash = true;
dosort = true;
}
else if (aggstate->aggstrategy == AGG_MIXED && phaseidx == 0)
{
/*
* No need to compute a transition function for an AGG_MIXED phase
* 0 - the contents of the hashtables will have been computed
* during phase 1.
*/
continue;
}
else if (phase->aggstrategy == AGG_PLAIN ||
phase->aggstrategy == AGG_SORTED)
{
dohash = false;
dosort = true;
}
else if (phase->aggstrategy == AGG_HASHED)
{
dohash = true;
dosort = false;
}
else
Assert(false);
phase->evaltrans = ExecBuildAggTrans(aggstate, phase, dosort, dohash);
}
return aggstate;
}
/*
* Build the state needed to calculate a state value for an aggregate.
*
* This initializes all the fields in 'pertrans'. 'aggref' is the aggregate
* to initialize the state for. 'aggtransfn', 'aggtranstype', and the rest
* of the arguments could be calculated from 'aggref', but the caller has
* calculated them already, so might as well pass them.
*/
static void
build_pertrans_for_aggref(AggStatePerTrans pertrans,
AggState *aggstate, EState *estate,
Aggref *aggref,
Oid aggtransfn, Oid aggtranstype,
Oid aggserialfn, Oid aggdeserialfn,
Datum initValue, bool initValueIsNull,
Oid *inputTypes, int numArguments)
{
int numGroupingSets = Max(aggstate->maxsets, 1);
Expr *serialfnexpr = NULL;
Expr *deserialfnexpr = NULL;
ListCell *lc;
int numInputs;
int numDirectArgs;
List *sortlist;
int numSortCols;
int numDistinctCols;
int i;
/* Begin filling in the pertrans data */
pertrans->aggref = aggref;
pertrans->aggshared = false;
pertrans->aggCollation = aggref->inputcollid;
pertrans->transfn_oid = aggtransfn;
pertrans->serialfn_oid = aggserialfn;
pertrans->deserialfn_oid = aggdeserialfn;
pertrans->initValue = initValue;
pertrans->initValueIsNull = initValueIsNull;
/* Count the "direct" arguments, if any */
numDirectArgs = list_length(aggref->aggdirectargs);
/* Count the number of aggregated input columns */
pertrans->numInputs = numInputs = list_length(aggref->args);
pertrans->aggtranstype = aggtranstype;
/* Detect how many arguments to pass to the transfn */
if (AGGKIND_IS_ORDERED_SET(aggref->aggkind))
pertrans->numTransInputs = numInputs;
else
pertrans->numTransInputs = numArguments;
/*
* When combining states, we have no use at all for the aggregate
* function's transfn. Instead we use the combinefn. In this case, the
* transfn and transfn_oid fields of pertrans refer to the combine
* function rather than the transition function.
*/
if (DO_AGGSPLIT_COMBINE(aggstate->aggsplit))
{
Expr *combinefnexpr;
build_aggregate_combinefn_expr(aggtranstype,
aggref->inputcollid,
aggtransfn,
&combinefnexpr);
fmgr_info(aggtransfn, &pertrans->transfn);
fmgr_info_set_expr((Node *) combinefnexpr, &pertrans->transfn);
InitFunctionCallInfoData(pertrans->transfn_fcinfo,
&pertrans->transfn,
2,
pertrans->aggCollation,
(void *) aggstate, NULL);
/*
* Ensure that a combine function to combine INTERNAL states is not
* strict. This should have been checked during CREATE AGGREGATE, but
* the strict property could have been changed since then.
*/
if (pertrans->transfn.fn_strict && aggtranstype == INTERNALOID)
ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("combine function with transition type %s must not be declared STRICT",
format_type_be(aggtranstype))));
}
else
{
Expr *transfnexpr;
/*
* Set up infrastructure for calling the transfn. Note that invtrans
* is not needed here.
*/
build_aggregate_transfn_expr(inputTypes,
numArguments,
numDirectArgs,
aggref->aggvariadic,
aggtranstype,
aggref->inputcollid,
aggtransfn,
InvalidOid,
&transfnexpr,
NULL);
fmgr_info(aggtransfn, &pertrans->transfn);
fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
InitFunctionCallInfoData(pertrans->transfn_fcinfo,
&pertrans->transfn,
pertrans->numTransInputs + 1,
pertrans->aggCollation,
(void *) aggstate, NULL);
/*
* If the transfn is strict and the initval is NULL, make sure input
* type and transtype are the same (or at least binary-compatible), so
* that it's OK to use the first aggregated input value as the initial
* transValue. This should have been checked at agg definition time,
* but we must check again in case the transfn's strictness property
* has been changed.
*/
if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
{
if (numArguments <= numDirectArgs ||
!IsBinaryCoercible(inputTypes[numDirectArgs],
aggtranstype))
ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("aggregate %u needs to have compatible input type and transition type",
aggref->aggfnoid)));
}
}
/* get info about the state value's datatype */
get_typlenbyval(aggtranstype,
&pertrans->transtypeLen,
&pertrans->transtypeByVal);
if (OidIsValid(aggserialfn))
{
build_aggregate_serialfn_expr(aggserialfn,
&serialfnexpr);
fmgr_info(aggserialfn, &pertrans->serialfn);
fmgr_info_set_expr((Node *) serialfnexpr, &pertrans->serialfn);
InitFunctionCallInfoData(pertrans->serialfn_fcinfo,
&pertrans->serialfn,
1,
InvalidOid,
(void *) aggstate, NULL);
}
if (OidIsValid(aggdeserialfn))
{
build_aggregate_deserialfn_expr(aggdeserialfn,
&deserialfnexpr);
fmgr_info(aggdeserialfn, &pertrans->deserialfn);
fmgr_info_set_expr((Node *) deserialfnexpr, &pertrans->deserialfn);
InitFunctionCallInfoData(pertrans->deserialfn_fcinfo,
&pertrans->deserialfn,
2,
InvalidOid,
(void *) aggstate, NULL);
}
/*
* If we're doing either DISTINCT or ORDER BY for a plain agg, then we
* have a list of SortGroupClause nodes; fish out the data in them and
* stick them into arrays. We ignore ORDER BY for an ordered-set agg,
* however; the agg's transfn and finalfn are responsible for that.
*
* Note that by construction, if there is a DISTINCT clause then the ORDER
* BY clause is a prefix of it (see transformDistinctClause).
*/
if (AGGKIND_IS_ORDERED_SET(aggref->aggkind))
{
sortlist = NIL;
numSortCols = numDistinctCols = 0;
}
else if (aggref->aggdistinct)
{
sortlist = aggref->aggdistinct;
numSortCols = numDistinctCols = list_length(sortlist);
Assert(numSortCols >= list_length(aggref->aggorder));
}
else
{
sortlist = aggref->aggorder;
numSortCols = list_length(sortlist);
numDistinctCols = 0;
}
pertrans->numSortCols = numSortCols;
pertrans->numDistinctCols = numDistinctCols;
/*
* If we have either sorting or filtering to do, create a tupledesc and
* slot corresponding to the aggregated inputs (including sort
* expressions) of the agg.
*/
if (numSortCols > 0 || aggref->aggfilter)
{
pertrans->sortdesc = ExecTypeFromTL(aggref->args, false);
pertrans->sortslot =
ExecInitExtraTupleSlot(estate, pertrans->sortdesc);
}
if (numSortCols > 0)
{
/*
* We don't implement DISTINCT or ORDER BY aggs in the HASHED case
* (yet)
*/
Assert(aggstate->aggstrategy != AGG_HASHED && aggstate->aggstrategy != AGG_MIXED);
/* If we have only one input, we need its len/byval info. */
if (numInputs == 1)
{
get_typlenbyval(inputTypes[numDirectArgs],
&pertrans->inputtypeLen,
&pertrans->inputtypeByVal);
}
else if (numDistinctCols > 0)
{
/* we will need an extra slot to store prior values */
pertrans->uniqslot =
ExecInitExtraTupleSlot(estate, pertrans->sortdesc);
}
/* Extract the sort information for use later */
pertrans->sortColIdx =
(AttrNumber *) palloc(numSortCols * sizeof(AttrNumber));
pertrans->sortOperators =
(Oid *) palloc(numSortCols * sizeof(Oid));
pertrans->sortCollations =
(Oid *) palloc(numSortCols * sizeof(Oid));
pertrans->sortNullsFirst =
(bool *) palloc(numSortCols * sizeof(bool));
i = 0;
foreach(lc, sortlist)
{
SortGroupClause *sortcl = (SortGroupClause *) lfirst(lc);
TargetEntry *tle = get_sortgroupclause_tle(sortcl, aggref->args);
/* the parser should have made sure of this */
Assert(OidIsValid(sortcl->sortop));
pertrans->sortColIdx[i] = tle->resno;
pertrans->sortOperators[i] = sortcl->sortop;
pertrans->sortCollations[i] = exprCollation((Node *) tle->expr);
pertrans->sortNullsFirst[i] = sortcl->nulls_first;
i++;
}
Assert(i == numSortCols);
}
if (aggref->aggdistinct)
{
Oid *ops;
Assert(numArguments > 0);
Assert(list_length(aggref->aggdistinct) == numDistinctCols);
ops = palloc(numDistinctCols * sizeof(Oid));
i = 0;
foreach(lc, aggref->aggdistinct)
ops[i++] = ((SortGroupClause *) lfirst(lc))->eqop;
/* lookup / build the necessary comparators */
if (numDistinctCols == 1)
fmgr_info(get_opcode(ops[0]), &pertrans->equalfnOne);
else
pertrans->equalfnMulti =
execTuplesMatchPrepare(pertrans->sortdesc,
numDistinctCols,
pertrans->sortColIdx,
ops,
&aggstate->ss.ps);
pfree(ops);
}
pertrans->sortstates = (Tuplesortstate **)
palloc0(sizeof(Tuplesortstate *) * numGroupingSets);
}
static Datum
GetAggInitVal(Datum textInitVal, Oid transtype)
{
Oid typinput,
typioparam;
char *strInitVal;
Datum initVal;
getTypeInputInfo(transtype, &typinput, &typioparam);
strInitVal = TextDatumGetCString(textInitVal);
initVal = OidInputFunctionCall(typinput, strInitVal,
typioparam, -1);
pfree(strInitVal);
return initVal;
}
/*
* find_compatible_peragg - search for a previously initialized per-Agg struct
*
* Searches the previously looked at aggregates to find one which is compatible
* with this one, with the same input parameters. If no compatible aggregate
* can be found, returns -1.
*
* As a side-effect, this also collects a list of existing, shareable per-Trans
* structs with matching inputs. If no identical Aggref is found, the list is
* passed later to find_compatible_pertrans, to see if we can at least reuse
* the state value of another aggregate.
*/
static int
find_compatible_peragg(Aggref *newagg, AggState *aggstate,
int lastaggno, List **same_input_transnos)
{
int aggno;
AggStatePerAgg peraggs;
*same_input_transnos = NIL;
/* we mustn't reuse the aggref if it contains volatile function calls */
if (contain_volatile_functions((Node *) newagg))
return -1;
peraggs = aggstate->peragg;
/*
* Search through the list of already seen aggregates. If we find an
* existing identical aggregate call, then we can re-use that one. While
* searching, we'll also collect a list of Aggrefs with the same input
* parameters. If no matching Aggref is found, the caller can potentially
* still re-use the transition state of one of them. (At this stage we
* just compare the parsetrees; whether different aggregates share the
* same transition function will be checked later.)
*/
for (aggno = 0; aggno <= lastaggno; aggno++)
{
AggStatePerAgg peragg;
Aggref *existingRef;
peragg = &peraggs[aggno];
existingRef = peragg->aggref;
/* all of the following must be the same or it's no match */
if (newagg->inputcollid != existingRef->inputcollid ||
newagg->aggtranstype != existingRef->aggtranstype ||
newagg->aggstar != existingRef->aggstar ||
newagg->aggvariadic != existingRef->aggvariadic ||
newagg->aggkind != existingRef->aggkind ||
!equal(newagg->args, existingRef->args) ||
!equal(newagg->aggorder, existingRef->aggorder) ||
!equal(newagg->aggdistinct, existingRef->aggdistinct) ||
!equal(newagg->aggfilter, existingRef->aggfilter))
continue;
/* if it's the same aggregate function then report exact match */
if (newagg->aggfnoid == existingRef->aggfnoid &&
newagg->aggtype == existingRef->aggtype &&
newagg->aggcollid == existingRef->aggcollid &&
equal(newagg->aggdirectargs, existingRef->aggdirectargs))
{
list_free(*same_input_transnos);
*same_input_transnos = NIL;
return aggno;
}
/*
* Not identical, but it had the same inputs. If the final function
* permits sharing, return its transno to the caller, in case we can
* re-use its per-trans state. (If there's already sharing going on,
* we might report a transno more than once. find_compatible_pertrans
* is cheap enough that it's not worth spending cycles to avoid that.)
*/
if (peragg->shareable)
*same_input_transnos = lappend_int(*same_input_transnos,
peragg->transno);
}
return -1;
}
/*
* find_compatible_pertrans - search for a previously initialized per-Trans
* struct
*
* Searches the list of transnos for a per-Trans struct with the same
* transition function and initial condition. (The inputs have already been
* verified to match.)
*/
static int
find_compatible_pertrans(AggState *aggstate, Aggref *newagg, bool shareable,
Oid aggtransfn, Oid aggtranstype,
Oid aggserialfn, Oid aggdeserialfn,
Datum initValue, bool initValueIsNull,
List *transnos)
{
ListCell *lc;
/* If this aggregate can't share transition states, give up */
if (!shareable)
return -1;
foreach(lc, transnos)
{
int transno = lfirst_int(lc);
AggStatePerTrans pertrans = &aggstate->pertrans[transno];
/*
* if the transfns or transition state types are not the same then the
* state can't be shared.
*/
if (aggtransfn != pertrans->transfn_oid ||
aggtranstype != pertrans->aggtranstype)
continue;
/*
* The serialization and deserialization functions must match, if
* present, as we're unable to share the trans state for aggregates
* which will serialize or deserialize into different formats.
* Remember that these will be InvalidOid if they're not required for
* this agg node.
*/
if (aggserialfn != pertrans->serialfn_oid ||
aggdeserialfn != pertrans->deserialfn_oid)
continue;
/*
* Check that the initial condition matches, too.
*/
if (initValueIsNull && pertrans->initValueIsNull)
return transno;
if (!initValueIsNull && !pertrans->initValueIsNull &&
datumIsEqual(initValue, pertrans->initValue,
pertrans->transtypeByVal, pertrans->transtypeLen))
return transno;
}
return -1;
}
void
ExecEndAgg(AggState *node)
{
PlanState *outerPlan;
int transno;
int numGroupingSets = Max(node->maxsets, 1);
int setno;
/* Make sure we have closed any open tuplesorts */
if (node->sort_in)
tuplesort_end(node->sort_in);
if (node->sort_out)
tuplesort_end(node->sort_out);
for (transno = 0; transno < node->numtrans; transno++)
{
AggStatePerTrans pertrans = &node->pertrans[transno];
for (setno = 0; setno < numGroupingSets; setno++)
{
if (pertrans->sortstates[setno])
tuplesort_end(pertrans->sortstates[setno]);
}
}
/* And ensure any agg shutdown callbacks have been called */
for (setno = 0; setno < numGroupingSets; setno++)
ReScanExprContext(node->aggcontexts[setno]);
if (node->hashcontext)
ReScanExprContext(node->hashcontext);
/*
* We don't actually free any ExprContexts here (see comment in
* ExecFreeExprContext), just unlinking the output one from the plan node
* suffices.
*/
ExecFreeExprContext(&node->ss.ps);
/* clean up tuple table */
ExecClearTuple(node->ss.ss_ScanTupleSlot);
outerPlan = outerPlanState(node);
ExecEndNode(outerPlan);
}
void
ExecReScanAgg(AggState *node)
{
ExprContext *econtext = node->ss.ps.ps_ExprContext;
PlanState *outerPlan = outerPlanState(node);
Agg *aggnode = (Agg *) node->ss.ps.plan;
int transno;
int numGroupingSets = Max(node->maxsets, 1);
int setno;
node->agg_done = false;
if (node->aggstrategy == AGG_HASHED)
{
/*
* In the hashed case, if we haven't yet built the hash table then we
* can just return; nothing done yet, so nothing to undo. If subnode's
* chgParam is not NULL then it will be re-scanned by ExecProcNode,
* else no reason to re-scan it at all.
*/
if (!node->table_filled)
return;
/*
* If we do have the hash table, and the subplan does not have any
* parameter changes, and none of our own parameter changes affect
* input expressions of the aggregated functions, then we can just
* rescan the existing hash table; no need to build it again.
*/
if (outerPlan->chgParam == NULL &&
!bms_overlap(node->ss.ps.chgParam, aggnode->aggParams))
{
ResetTupleHashIterator(node->perhash[0].hashtable,
&node->perhash[0].hashiter);
select_current_set(node, 0, true);
return;
}
}
/* Make sure we have closed any open tuplesorts */
for (transno = 0; transno < node->numtrans; transno++)
{
for (setno = 0; setno < numGroupingSets; setno++)
{
AggStatePerTrans pertrans = &node->pertrans[transno];
if (pertrans->sortstates[setno])
{
tuplesort_end(pertrans->sortstates[setno]);
pertrans->sortstates[setno] = NULL;
}
}
}
/*
* We don't need to ReScanExprContext the output tuple context here;
* ExecReScan already did it. But we do need to reset our per-grouping-set
* contexts, which may have transvalues stored in them. (We use rescan
* rather than just reset because transfns may have registered callbacks
* that need to be run now.) For the AGG_HASHED case, see below.
*/
for (setno = 0; setno < numGroupingSets; setno++)
{
ReScanExprContext(node->aggcontexts[setno]);
}
/* Release first tuple of group, if we have made a copy */
if (node->grp_firstTuple != NULL)
{
heap_freetuple(node->grp_firstTuple);
node->grp_firstTuple = NULL;
}
ExecClearTuple(node->ss.ss_ScanTupleSlot);
/* Forget current agg values */
MemSet(econtext->ecxt_aggvalues, 0, sizeof(Datum) * node->numaggs);
MemSet(econtext->ecxt_aggnulls, 0, sizeof(bool) * node->numaggs);
/*
* With AGG_HASHED/MIXED, the hash table is allocated in a sub-context of
* the hashcontext. This used to be an issue, but now, resetting a context
* automatically deletes sub-contexts too.
*/
if (node->aggstrategy == AGG_HASHED || node->aggstrategy == AGG_MIXED)
{
ReScanExprContext(node->hashcontext);
/* Rebuild an empty hash table */
build_hash_table(node);
node->table_filled = false;
/* iterator will be reset when the table is filled */
}
if (node->aggstrategy != AGG_HASHED)
{
/*
* Reset the per-group state (in particular, mark transvalues null)
*/
for (setno = 0; setno < numGroupingSets; setno++)
{
MemSet(node->pergroups[setno], 0,
sizeof(AggStatePerGroupData) * node->numaggs);
}
/* reset to phase 1 */
initialize_phase(node, 1);
node->input_done = false;
node->projected_set = -1;
}
if (outerPlan->chgParam == NULL)
ExecReScan(outerPlan);
}
/***********************************************************************
* API exposed to aggregate functions
***********************************************************************/
/*
* AggCheckCallContext - test if a SQL function is being called as an aggregate
*
* The transition and/or final functions of an aggregate may want to verify
* that they are being called as aggregates, rather than as plain SQL
* functions. They should use this function to do so. The return value
* is nonzero if being called as an aggregate, or zero if not. (Specific
* nonzero values are AGG_CONTEXT_AGGREGATE or AGG_CONTEXT_WINDOW, but more
* values could conceivably appear in future.)
*
* If aggcontext isn't NULL, the function also stores at *aggcontext the
* identity of the memory context that aggregate transition values are being
* stored in. Note that the same aggregate call site (flinfo) may be called
* interleaved on different transition values in different contexts, so it's
* not kosher to cache aggcontext under fn_extra. It is, however, kosher to
* cache it in the transvalue itself (for internal-type transvalues).
*/
int
AggCheckCallContext(FunctionCallInfo fcinfo, MemoryContext *aggcontext)
{
if (fcinfo->context && IsA(fcinfo->context, AggState))
{
if (aggcontext)
{
AggState *aggstate = ((AggState *) fcinfo->context);
ExprContext *cxt = aggstate->curaggcontext;
*aggcontext = cxt->ecxt_per_tuple_memory;
}
return AGG_CONTEXT_AGGREGATE;
}
if (fcinfo->context && IsA(fcinfo->context, WindowAggState))
{
if (aggcontext)
*aggcontext = ((WindowAggState *) fcinfo->context)->curaggcontext;
return AGG_CONTEXT_WINDOW;
}
/* this is just to prevent "uninitialized variable" warnings */
if (aggcontext)
*aggcontext = NULL;
return 0;
}
/*
* AggGetAggref - allow an aggregate support function to get its Aggref
*
* If the function is being called as an aggregate support function,
* return the Aggref node for the aggregate call. Otherwise, return NULL.
*
* Aggregates sharing the same inputs and transition functions can get
* merged into a single transition calculation. If the transition function
* calls AggGetAggref, it will get some one of the Aggrefs for which it is
* executing. It must therefore not pay attention to the Aggref fields that
* relate to the final function, as those are indeterminate. But if a final
* function calls AggGetAggref, it will get a precise result.
*
* Note that if an aggregate is being used as a window function, this will
* return NULL. We could provide a similar function to return the relevant
* WindowFunc node in such cases, but it's not needed yet.
*/
Aggref *
AggGetAggref(FunctionCallInfo fcinfo)
{
if (fcinfo->context && IsA(fcinfo->context, AggState))
{
AggState *aggstate = (AggState *) fcinfo->context;
AggStatePerAgg curperagg;
AggStatePerTrans curpertrans;
/* check curperagg (valid when in a final function) */
curperagg = aggstate->curperagg;
if (curperagg)
return curperagg->aggref;
/* check curpertrans (valid when in a transition function) */
curpertrans = aggstate->curpertrans;
if (curpertrans)
return curpertrans->aggref;
}
return NULL;
}
/*
* AggGetTempMemoryContext - fetch short-term memory context for aggregates
*
* This is useful in agg final functions; the context returned is one that
* the final function can safely reset as desired. This isn't useful for
* transition functions, since the context returned MAY (we don't promise)
* be the same as the context those are called in.
*
* As above, this is currently not useful for aggs called as window functions.
*/
MemoryContext
AggGetTempMemoryContext(FunctionCallInfo fcinfo)
{
if (fcinfo->context && IsA(fcinfo->context, AggState))
{
AggState *aggstate = (AggState *) fcinfo->context;
return aggstate->tmpcontext->ecxt_per_tuple_memory;
}
return NULL;
}
/*
* AggStateIsShared - find out whether transition state is shared
*
* If the function is being called as an aggregate support function,
* return true if the aggregate's transition state is shared across
* multiple aggregates, false if it is not.
*
* Returns true if not called as an aggregate support function.
* This is intended as a conservative answer, ie "no you'd better not
* scribble on your input". In particular, will return true if the
* aggregate is being used as a window function, which is a scenario
* in which changing the transition state is a bad idea. We might
* want to refine the behavior for the window case in future.
*/
bool
AggStateIsShared(FunctionCallInfo fcinfo)
{
if (fcinfo->context && IsA(fcinfo->context, AggState))
{
AggState *aggstate = (AggState *) fcinfo->context;
AggStatePerAgg curperagg;
AggStatePerTrans curpertrans;
/* check curperagg (valid when in a final function) */
curperagg = aggstate->curperagg;
if (curperagg)
return aggstate->pertrans[curperagg->transno].aggshared;
/* check curpertrans (valid when in a transition function) */
curpertrans = aggstate->curpertrans;
if (curpertrans)
return curpertrans->aggshared;
}
return true;
}
/*
* AggRegisterCallback - register a cleanup callback for an aggregate
*
* This is useful for aggs to register shutdown callbacks, which will ensure
* that non-memory resources are freed. The callback will occur just before
* the associated aggcontext (as returned by AggCheckCallContext) is reset,
* either between groups or as a result of rescanning the query. The callback
* will NOT be called on error paths. The typical use-case is for freeing of
* tuplestores or tuplesorts maintained in aggcontext, or pins held by slots
* created by the agg functions. (The callback will not be called until after
* the result of the finalfn is no longer needed, so it's safe for the finalfn
* to return data that will be freed by the callback.)
*
* As above, this is currently not useful for aggs called as window functions.
*/
void
AggRegisterCallback(FunctionCallInfo fcinfo,
ExprContextCallbackFunction func,
Datum arg)
{
if (fcinfo->context && IsA(fcinfo->context, AggState))
{
AggState *aggstate = (AggState *) fcinfo->context;
ExprContext *cxt = aggstate->curaggcontext;
RegisterExprContextCallback(cxt, func, arg);
return;
}
elog(ERROR, "aggregate function cannot register a callback in this context");
}
/*
* aggregate_dummy - dummy execution routine for aggregate functions
*
* This function is listed as the implementation (prosrc field) of pg_proc
* entries for aggregate functions. Its only purpose is to throw an error
* if someone mistakenly executes such a function in the normal way.
*
* Perhaps someday we could assign real meaning to the prosrc field of
* an aggregate?
*/
Datum
aggregate_dummy(PG_FUNCTION_ARGS)
{
elog(ERROR, "aggregate function %u called as normal function",
fcinfo->flinfo->fn_oid);
return (Datum) 0; /* keep compiler quiet */
}