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nodeAgg.c 51.47 KiB
/*-------------------------------------------------------------------------
*
* nodeAgg.c
* Routines to handle aggregate nodes.
*
* ExecAgg evaluates each aggregate in the following steps:
*
* transvalue = initcond
* foreach input_tuple do
* transvalue = transfunc(transvalue, input_value(s))
* result = finalfunc(transvalue)
*
* If a finalfunc is not supplied then the result is just the ending
* value of transvalue.
*
* 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.
*
* 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 the memory context aggstate->aggcontext,
* which is also used for the hashtable structures in AGG_HASHED mode.
* The node's regular econtext (aggstate->csstate.cstate.cs_ExprContext)
* is used to run finalize functions and compute the output tuple;
* this context can be reset once per output tuple.
*
* Beginning in PostgreSQL 8.1, the executor's AggState node is passed as
* the fmgr "context" value in all transfunc and finalfunc calls. It is
* not really intended that the transition functions will look into the
* AggState node, but they can use code like
* if (fcinfo->context && IsA(fcinfo->context, AggState))
* 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
* that is 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 advance_transition_function() is coded to avoid a
* data copy step when the previous transition value pointer is returned.
* Also, some transition functions make use of the aggcontext to store
* working state.
*
*
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeAgg.c,v 1.169 2009/09/27 21:10:53 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.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/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "parser/parse_agg.h"
#include "parser/parse_coerce.h"
#include "parser/parse_oper.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"
/*
* AggStatePerAggData - per-aggregate working state for the Agg scan
*/
typedef struct AggStatePerAggData
{
/*
* These values are set up during ExecInitAgg() and do not change
* thereafter:
*/
/* Links to Aggref expr and state nodes this working state is for */
AggrefExprState *aggrefstate;
Aggref *aggref;
/* number of input arguments for aggregate */
int numArguments;
/* Oids of transfer functions */
Oid transfn_oid;
Oid finalfn_oid; /* may be InvalidOid */
/*
* fmgr lookup data for transfer functions --- only valid when
* corresponding oid is not InvalidOid. Note in particular that fn_strict
* flags are kept here.
*/
FmgrInfo transfn;
FmgrInfo finalfn;
/*
* Type of input data and Oid of sort operator to use for it; only
* set/used when aggregate has DISTINCT flag. (These are not used
* directly by nodeAgg, but must be passed to the Tuplesort object.)
*/
Oid inputType;
Oid sortOperator;
/*
* fmgr lookup data for input type's equality operator --- only set/used
* when aggregate has DISTINCT flag.
*/
FmgrInfo equalfn;
/*
* initial value from pg_aggregate entry
*/
Datum initValue;
bool initValueIsNull;
/*
* We need the len and byval info for the agg's input, result, and
* transition data types in order to know how to copy/delete values.
*/
int16 inputtypeLen,
resulttypeLen,
transtypeLen;
bool inputtypeByVal,
resulttypeByVal,
transtypeByVal;
/*
* These values are working state that is initialized at the start of an
* input tuple group and updated for each input tuple.
*
* For a simple (non DISTINCT) aggregate, we just feed the input values
* straight to the transition function. If it's DISTINCT, we pass the
* input values into a Tuplesort object; then at completion of the input
* tuple group, we scan the sorted values, eliminate duplicates, and run
* the transition function on the rest.
*/
Tuplesortstate *sortstate; /* sort object, if a DISTINCT agg */
} AggStatePerAggData;
/*
* AggStatePerGroupData - per-aggregate-per-group working state
*
* These values are working state that is initialized at the start of
* an input tuple group and updated for each input tuple.
*
* In AGG_PLAIN and AGG_SORTED modes, we have a single array of these
* structs (pointed to by aggstate->pergroup); we re-use the array for
* each input group, if it's AGG_SORTED mode. In AGG_HASHED mode, the
* hash table contains an array of these structs for each tuple group.
*
* Logically, the sortstate field belongs in this struct, but we do not
* keep it here for space reasons: we don't support DISTINCT aggregates
* in AGG_HASHED mode, so there's no reason to use up a pointer field
* in every entry of the hashtable.
*/
typedef struct AggStatePerGroupData
{
Datum transValue; /* current transition value */
bool transValueIsNull;
bool noTransValue; /* true if transValue not set yet */
/*
* Note: noTransValue initially has the same value as transValueIsNull,
* and if true both are cleared to false at the same time. They are not
* the same though: if transfn later returns a NULL, we want to keep that
* NULL and not auto-replace it with a later input value. Only the first
* non-NULL input will be auto-substituted.
*/
} AggStatePerGroupData;
/*
* 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.
*/
typedef struct AggHashEntryData *AggHashEntry;
typedef struct AggHashEntryData
{
TupleHashEntryData shared; /* common header for hash table entries */
/* per-aggregate transition status array - must be last! */ AggStatePerGroupData pergroup[1]; /* VARIABLE LENGTH ARRAY */
} AggHashEntryData; /* VARIABLE LENGTH STRUCT */
static void initialize_aggregates(AggState *aggstate,
AggStatePerAgg peragg,
AggStatePerGroup pergroup);
static void advance_transition_function(AggState *aggstate,
AggStatePerAgg peraggstate,
AggStatePerGroup pergroupstate,
FunctionCallInfoData *fcinfo);
static void advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
static void process_sorted_aggregate(AggState *aggstate,
AggStatePerAgg peraggstate,
AggStatePerGroup pergroupstate);
static void finalize_aggregate(AggState *aggstate,
AggStatePerAgg peraggstate,
AggStatePerGroup pergroupstate,
Datum *resultVal, bool *resultIsNull);
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 AggHashEntry lookup_hash_entry(AggState *aggstate,
TupleTableSlot *inputslot);
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);
/*
* Initialize all aggregates for a new group of input values.
*
* When called, CurrentMemoryContext should be the per-query context.
*/
static void
initialize_aggregates(AggState *aggstate,
AggStatePerAgg peragg,
AggStatePerGroup pergroup)
{
int aggno;
for (aggno = 0; aggno < aggstate->numaggs; aggno++)
{
AggStatePerAgg peraggstate = &peragg[aggno];
AggStatePerGroup pergroupstate = &pergroup[aggno];
Aggref *aggref = peraggstate->aggref;
/*
* Start a fresh sort operation for each DISTINCT aggregate.
*/
if (aggref->aggdistinct)
{
/*
* In case of rescan, maybe there could be an uncompleted sort
* operation? Clean it up if so.
*/
if (peraggstate->sortstate)
tuplesort_end(peraggstate->sortstate);
peraggstate->sortstate =
tuplesort_begin_datum(peraggstate->inputType,
peraggstate->sortOperator, false,
work_mem, 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 (peraggstate->initValueIsNull)
pergroupstate->transValue = peraggstate->initValue;
else
{
MemoryContext oldContext;
oldContext = MemoryContextSwitchTo(aggstate->aggcontext);
pergroupstate->transValue = datumCopy(peraggstate->initValue,
peraggstate->transtypeByVal,
peraggstate->transtypeLen);
MemoryContextSwitchTo(oldContext);
}
pergroupstate->transValueIsNull = peraggstate->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 = peraggstate->initValueIsNull;
}
}
/*
* Given new input value(s), advance the transition function of an aggregate.
*
* The new values (and null flags) have been preloaded into argument positions
* 1 and up in fcinfo, so that we needn't copy them again to pass to the
* transition function. No other fields of fcinfo are assumed valid.
*
* It doesn't matter which memory context this is called in.
*/
static void
advance_transition_function(AggState *aggstate,
AggStatePerAgg peraggstate,
AggStatePerGroup pergroupstate,
FunctionCallInfoData *fcinfo)
{
int numArguments = peraggstate->numArguments;
MemoryContext oldContext;
Datum newVal;
int i;
if (peraggstate->transfn.fn_strict)
{
/*
* For a strict transfn, nothing happens when there's a NULL input; we
* just keep the prior transValue.
*/
for (i = 1; i <= numArguments; 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->aggcontext); pergroupstate->transValue = datumCopy(fcinfo->arg[1],
peraggstate->transtypeByVal,
peraggstate->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);
/*
* OK to call the transition function
*/
InitFunctionCallInfoData(*fcinfo, &(peraggstate->transfn),
numArguments + 1,
(void *) aggstate, NULL);
fcinfo->arg[0] = pergroupstate->transValue;
fcinfo->argnull[0] = pergroupstate->transValueIsNull;
newVal = FunctionCallInvoke(fcinfo);
/*
* If pass-by-ref datatype, must copy the new value into aggcontext and
* pfree the prior transValue. But if transfn returned a pointer to its
* first input, we don't need to do anything.
*/
if (!peraggstate->transtypeByVal &&
DatumGetPointer(newVal) != DatumGetPointer(pergroupstate->transValue))
{
if (!fcinfo->isnull)
{
MemoryContextSwitchTo(aggstate->aggcontext);
newVal = datumCopy(newVal,
peraggstate->transtypeByVal,
peraggstate->transtypeLen);
}
if (!pergroupstate->transValueIsNull)
pfree(DatumGetPointer(pergroupstate->transValue));
}
pergroupstate->transValue = newVal;
pergroupstate->transValueIsNull = fcinfo->isnull;
MemoryContextSwitchTo(oldContext);
}
/*
* Advance all the aggregates for one input tuple. The input tuple
* has been stored in tmpcontext->ecxt_outertuple, so that it is accessible
* to ExecEvalExpr. pergroup is the array of per-group structs to use
* (this might be in a hashtable entry).
*
* When called, CurrentMemoryContext should be the per-query context.
*/
static void
advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
{ ExprContext *econtext = aggstate->tmpcontext;
int aggno;
for (aggno = 0; aggno < aggstate->numaggs; aggno++)
{
AggStatePerAgg peraggstate = &aggstate->peragg[aggno];
AggStatePerGroup pergroupstate = &pergroup[aggno];
AggrefExprState *aggrefstate = peraggstate->aggrefstate;
Aggref *aggref = peraggstate->aggref;
FunctionCallInfoData fcinfo;
int i;
ListCell *arg;
MemoryContext oldContext;
/* Switch memory context just once for all args */
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
/* Evaluate inputs and save in fcinfo */
/* We start from 1, since the 0th arg will be the transition value */
i = 1;
foreach(arg, aggrefstate->args)
{
ExprState *argstate = (ExprState *) lfirst(arg);
fcinfo.arg[i] = ExecEvalExpr(argstate, econtext,
fcinfo.argnull + i, NULL);
i++;
}
/* Switch back */
MemoryContextSwitchTo(oldContext);
if (aggref->aggdistinct)
{
/* in DISTINCT mode, we may ignore nulls */
/* XXX we assume there is only one input column */
if (fcinfo.argnull[1])
continue;
tuplesort_putdatum(peraggstate->sortstate, fcinfo.arg[1],
fcinfo.argnull[1]);
}
else
{
advance_transition_function(aggstate, peraggstate, pergroupstate,
&fcinfo);
}
}
}
/*
* Run the transition function for a DISTINCT aggregate. 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 non-duplicate value.
*
* When called, CurrentMemoryContext should be the per-query context.
*/
static void
process_sorted_aggregate(AggState *aggstate,
AggStatePerAgg peraggstate,
AggStatePerGroup pergroupstate)
{
Datum oldVal = (Datum) 0;
bool haveOldVal = false;
MemoryContext workcontext = aggstate->tmpcontext->ecxt_per_tuple_memory;
MemoryContext oldContext;
Datum *newVal;
bool *isNull;
FunctionCallInfoData fcinfo;
tuplesort_performsort(peraggstate->sortstate);
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(peraggstate->sortstate, true,
newVal, isNull))
{
/*
* DISTINCT always suppresses nulls, per SQL spec, regardless of the
* transition function's strictness.
*/
if (*isNull)
continue;
/*
* Clear and select the working context for evaluation of the equality
* function and transition function.
*/
MemoryContextReset(workcontext);
oldContext = MemoryContextSwitchTo(workcontext);
if (haveOldVal &&
DatumGetBool(FunctionCall2(&peraggstate->equalfn,
oldVal, *newVal)))
{
/* equal to prior, so forget this one */
if (!peraggstate->inputtypeByVal)
pfree(DatumGetPointer(*newVal));
}
else
{
advance_transition_function(aggstate, peraggstate, pergroupstate,
&fcinfo);
/* forget the old value, if any */
if (haveOldVal && !peraggstate->inputtypeByVal)
pfree(DatumGetPointer(oldVal));
/* and remember the new one for subsequent equality checks */
oldVal = *newVal;
haveOldVal = true;
}
MemoryContextSwitchTo(oldContext);
}
if (haveOldVal && !peraggstate->inputtypeByVal)
pfree(DatumGetPointer(oldVal));
tuplesort_end(peraggstate->sortstate);
peraggstate->sortstate = NULL;
}
/*
* Compute the final value of one aggregate.
*
* The finalfunction will be run, and the result delivered, in the
* output-tuple context; caller's CurrentMemoryContext does not matter.
*/
static void
finalize_aggregate(AggState *aggstate,
AggStatePerAgg peraggstate,
AggStatePerGroup pergroupstate,
Datum *resultVal, bool *resultIsNull)
{ MemoryContext oldContext;
oldContext = MemoryContextSwitchTo(aggstate->ss.ps.ps_ExprContext->ecxt_per_tuple_memory);
/*
* Apply the agg's finalfn if one is provided, else return transValue.
*/
if (OidIsValid(peraggstate->finalfn_oid))
{
FunctionCallInfoData fcinfo;
InitFunctionCallInfoData(fcinfo, &(peraggstate->finalfn), 1,
(void *) aggstate, NULL);
fcinfo.arg[0] = pergroupstate->transValue;
fcinfo.argnull[0] = pergroupstate->transValueIsNull;
if (fcinfo.flinfo->fn_strict && pergroupstate->transValueIsNull)
{
/* don't call a strict function with NULL inputs */
*resultVal = (Datum) 0;
*resultIsNull = true;
}
else
{
*resultVal = FunctionCallInvoke(&fcinfo);
*resultIsNull = fcinfo.isnull;
}
}
else
{
*resultVal = pergroupstate->transValue;
*resultIsNull = pergroupstate->transValueIsNull;
}
/*
* If result is pass-by-ref, make sure it is in the right context.
*/
if (!peraggstate->resulttypeByVal && !*resultIsNull &&
!MemoryContextContains(CurrentMemoryContext,
DatumGetPointer(*resultVal)))
*resultVal = datumCopy(*resultVal,
peraggstate->resulttypeByVal,
peraggstate->resulttypeLen);
MemoryContextSwitchTo(oldContext);
}
/*
* 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 */
Assert(var->varno == OUTER);
Assert(var->varlevelsup == 0);
*colnos = bms_add_member(*colnos, var->varattno);
return false;
}
if (IsA(node, Aggref)) /* do not descend into aggregate exprs */
return false;
return expression_tree_walker(node, find_unaggregated_cols_walker,
(void *) colnos);
}
/*
* Initialize the hash table to empty.
*
* The hash table always lives in the aggcontext memory context.
*/
static void
build_hash_table(AggState *aggstate)
{
Agg *node = (Agg *) aggstate->ss.ps.plan;
MemoryContext tmpmem = aggstate->tmpcontext->ecxt_per_tuple_memory;
Size entrysize;
Assert(node->aggstrategy == AGG_HASHED);
Assert(node->numGroups > 0);
entrysize = sizeof(AggHashEntryData) +
(aggstate->numaggs - 1) *sizeof(AggStatePerGroupData);
aggstate->hashtable = BuildTupleHashTable(node->numCols,
node->grpColIdx,
aggstate->eqfunctions,
aggstate->hashfunctions,
node->numGroups,
entrysize,
aggstate->aggcontext,
tmpmem);
}
/*
* Create a list of the tuple 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. To avoid messing up Var
* numbering, we keep the same tuple descriptor for hashtable entries as the
* incoming tuples have, but set unwanted columns to NULL in the tuples that
* go into the table.
*
* To eliminate duplicates, we build a bitmapset of the needed columns, then
* convert it to an integer list (cheaper to scan at runtime). The list is
* in decreasing order so that the first entry is the largest;
* lookup_hash_entry depends on this to use slot_getsomeattrs correctly.
* Note that the list is preserved over ExecReScanAgg, so we allocate it in
* the per-query context (unlike the hash table itself).
*
* Note: at present, searching the tlist/qual is not really necessary since
* the parser should disallow any unaggregated references to ungrouped
* columns. However, the search will be needed when we add support for
* SQL99 semantics that allow use of "functionally dependent" columns that
* haven't been explicitly grouped by.
*/
static List *find_hash_columns(AggState *aggstate)
{
Agg *node = (Agg *) aggstate->ss.ps.plan;
Bitmapset *colnos;
List *collist;
int i;
/* Find Vars that will be needed in tlist and qual */
colnos = find_unaggregated_cols(aggstate);
/* Add in all the grouping columns */
for (i = 0; i < node->numCols; i++)
colnos = bms_add_member(colnos, node->grpColIdx[i]);
/* Convert to list, using lcons so largest element ends up first */
collist = NIL;
while ((i = bms_first_member(colnos)) >= 0)
collist = lcons_int(i, collist);
bms_free(colnos);
return collist;
}
/*
* 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.
*/
Size
hash_agg_entry_size(int numAggs)
{
Size entrysize;
/* This must match build_hash_table */
entrysize = sizeof(AggHashEntryData) +
(numAggs - 1) *sizeof(AggStatePerGroupData);
entrysize = MAXALIGN(entrysize);
/* Account for hashtable overhead (assuming fill factor = 1) */
entrysize += 3 * sizeof(void *);
return entrysize;
}
/*
* Find or create a hashtable entry for the tuple group containing the
* given tuple.
*
* When called, CurrentMemoryContext should be the per-query context.
*/
static AggHashEntry
lookup_hash_entry(AggState *aggstate, TupleTableSlot *inputslot)
{
TupleTableSlot *hashslot = aggstate->hashslot;
ListCell *l;
AggHashEntry entry;
bool isnew;
/* if first time through, initialize hashslot by cloning input slot */
if (hashslot->tts_tupleDescriptor == NULL)
{
ExecSetSlotDescriptor(hashslot, inputslot->tts_tupleDescriptor);
/* Make sure all unused columns are NULLs */
ExecStoreAllNullTuple(hashslot);
}
/* transfer just the needed columns into hashslot */
slot_getsomeattrs(inputslot, linitial_int(aggstate->hash_needed));
foreach(l, aggstate->hash_needed)
{
int varNumber = lfirst_int(l) - 1;
hashslot->tts_values[varNumber] = inputslot->tts_values[varNumber]; hashslot->tts_isnull[varNumber] = inputslot->tts_isnull[varNumber];
}
/* find or create the hashtable entry using the filtered tuple */
entry = (AggHashEntry) LookupTupleHashEntry(aggstate->hashtable,
hashslot,
&isnew);
if (isnew)
{
/* initialize aggregates for new tuple group */
initialize_aggregates(aggstate, aggstate->peragg, entry->pergroup);
}
return entry;
}
/*
* 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.
*/
TupleTableSlot *
ExecAgg(AggState *node)
{
/*
* Check to see if we're still projecting out tuples from a previous agg
* tuple (because there is a function-returning-set in the projection
* expressions). If so, try to project another one.
*/
if (node->ss.ps.ps_TupFromTlist)
{
TupleTableSlot *result;
ExprDoneCond isDone;
result = ExecProject(node->ss.ps.ps_ProjInfo, &isDone);
if (isDone == ExprMultipleResult)
return result;
/* Done with that source tuple... */
node->ss.ps.ps_TupFromTlist = false;
}
/*
* Exit if nothing left to do. (We must do the ps_TupFromTlist check
* first, because in some cases agg_done gets set before we emit the
* final aggregate tuple, and we have to finish running SRFs for it.)
*/
if (node->agg_done)
return NULL;
/* Dispatch based on strategy */
if (((Agg *) node->ss.ps.plan)->aggstrategy == AGG_HASHED)
{
if (!node->table_filled)
agg_fill_hash_table(node);
return agg_retrieve_hash_table(node);
}
else
return agg_retrieve_direct(node);
}
/* * ExecAgg for non-hashed case
*/
static TupleTableSlot *
agg_retrieve_direct(AggState *aggstate)
{
Agg *node = (Agg *) aggstate->ss.ps.plan;
PlanState *outerPlan;
ExprContext *econtext;
ExprContext *tmpcontext;
Datum *aggvalues;
bool *aggnulls;
AggStatePerAgg peragg;
AggStatePerGroup pergroup;
TupleTableSlot *outerslot;
TupleTableSlot *firstSlot;
int aggno;
/*
* get state info from node
*/
outerPlan = outerPlanState(aggstate);
/* econtext is the per-output-tuple expression context */
econtext = aggstate->ss.ps.ps_ExprContext;
aggvalues = econtext->ecxt_aggvalues;
aggnulls = econtext->ecxt_aggnulls;
/* tmpcontext is the per-input-tuple expression context */
tmpcontext = aggstate->tmpcontext;
peragg = aggstate->peragg;
pergroup = aggstate->pergroup;
firstSlot = aggstate->ss.ss_ScanTupleSlot;
/*
* We loop retrieving groups until we find one matching
* aggstate->ss.ps.qual
*/
while (!aggstate->agg_done)
{
/*
* 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 = ExecProcNode(outerPlan);
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 */
aggstate->agg_done = true;
/* If we are grouping, we should produce no tuples too */
if (node->aggstrategy != AGG_PLAIN)
return NULL;
}
}
/*
* Clear the per-output-tuple context for each group, as well as
* aggcontext (which contains any pass-by-ref transvalues of the
* old group). We also clear any child contexts of the aggcontext;
* some aggregate functions store working state in such contexts.
*/
ResetExprContext(econtext);
MemoryContextResetAndDeleteChildren(aggstate->aggcontext);
/*
* Initialize working state for a new input tuple group
*/
initialize_aggregates(aggstate, peragg, pergroup);
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 (;;)
{
advance_aggregates(aggstate, pergroup);
/* Reset per-input-tuple context after each tuple */
ResetExprContext(tmpcontext);
outerslot = ExecProcNode(outerPlan);
if (TupIsNull(outerslot))
{
/* no more outer-plan tuples available */
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_SORTED)
{
if (!execTuplesMatch(firstSlot,
outerslot,
node->numCols, node->grpColIdx,
aggstate->eqfunctions,
tmpcontext->ecxt_per_tuple_memory))
{
/*
* Save the first input tuple of the next group.
*/
aggstate->grp_firstTuple = ExecCopySlotTuple(outerslot);
break;
}
}
}
}
/*
* Done scanning input tuple group. Finalize each aggregate
* calculation, and stash results in the per-output-tuple context.
*/ for (aggno = 0; aggno < aggstate->numaggs; aggno++)
{
AggStatePerAgg peraggstate = &peragg[aggno];
AggStatePerGroup pergroupstate = &pergroup[aggno];
if (peraggstate->aggref->aggdistinct)
process_sorted_aggregate(aggstate, peraggstate, pergroupstate);
finalize_aggregate(aggstate, peraggstate, pergroupstate,
&aggvalues[aggno], &aggnulls[aggno]);
}
/*
* Use the representative input tuple for any references to
* non-aggregated input columns in the qual and 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;
/*
* Check the qual (HAVING clause); if the group does not match, ignore
* it and loop back to try to process another group.
*/
if (ExecQual(aggstate->ss.ps.qual, econtext, false))
{
/*
* Form and return a projection tuple using the aggregate results
* and the representative input tuple.
*/
TupleTableSlot *result;
ExprDoneCond isDone;
result = ExecProject(aggstate->ss.ps.ps_ProjInfo, &isDone);
if (isDone != ExprEndResult)
{
aggstate->ss.ps.ps_TupFromTlist =
(isDone == ExprMultipleResult);
return result;
}
}
}
/* No more groups */
return NULL;
}
/*
* ExecAgg for hashed case: phase 1, read input and build hash table
*/
static void
agg_fill_hash_table(AggState *aggstate)
{
PlanState *outerPlan;
ExprContext *tmpcontext;
AggHashEntry entry;
TupleTableSlot *outerslot;
/*
* get state info from node
*/
outerPlan = outerPlanState(aggstate);
/* tmpcontext is the per-input-tuple expression context */
tmpcontext = aggstate->tmpcontext;
/*
* Process each outer-plan tuple, and then fetch the next one, until we
* exhaust the outer plan. */
for (;;)
{
outerslot = ExecProcNode(outerPlan);
if (TupIsNull(outerslot))
break;
/* set up for advance_aggregates call */
tmpcontext->ecxt_outertuple = outerslot;
/* Find or build hashtable entry for this tuple's group */
entry = lookup_hash_entry(aggstate, outerslot);
/* Advance the aggregates */
advance_aggregates(aggstate, entry->pergroup);
/* Reset per-input-tuple context after each tuple */
ResetExprContext(tmpcontext);
}
aggstate->table_filled = true;
/* Initialize to walk the hash table */
ResetTupleHashIterator(aggstate->hashtable, &aggstate->hashiter);
}
/*
* ExecAgg for hashed case: phase 2, retrieving groups from hash table
*/
static TupleTableSlot *
agg_retrieve_hash_table(AggState *aggstate)
{
ExprContext *econtext;
Datum *aggvalues;
bool *aggnulls;
AggStatePerAgg peragg;
AggStatePerGroup pergroup;
AggHashEntry entry;
TupleTableSlot *firstSlot;
int aggno;
/*
* get state info from node
*/
/* econtext is the per-output-tuple expression context */
econtext = aggstate->ss.ps.ps_ExprContext;
aggvalues = econtext->ecxt_aggvalues;
aggnulls = econtext->ecxt_aggnulls;
peragg = aggstate->peragg;
firstSlot = aggstate->ss.ss_ScanTupleSlot;
/*
* We loop retrieving groups until we find one satisfying
* aggstate->ss.ps.qual
*/
while (!aggstate->agg_done)
{
/*
* Find the next entry in the hash table
*/
entry = (AggHashEntry) ScanTupleHashTable(&aggstate->hashiter);
if (entry == NULL)
{
/* No more entries in hashtable, so done */
aggstate->agg_done = TRUE;
return NULL;
}
/*
* Clear the per-output-tuple context for each group
*/
ResetExprContext(econtext);
/*
* Store the copied first input tuple in the tuple table slot reserved
* for it, so that it can be used in ExecProject.
*/
ExecStoreMinimalTuple(entry->shared.firstTuple,
firstSlot,
false);
pergroup = entry->pergroup;
/*
* Finalize each aggregate calculation, and stash results in the
* per-output-tuple context.
*/
for (aggno = 0; aggno < aggstate->numaggs; aggno++)
{
AggStatePerAgg peraggstate = &peragg[aggno];
AggStatePerGroup pergroupstate = &pergroup[aggno];
Assert(!peraggstate->aggref->aggdistinct);
finalize_aggregate(aggstate, peraggstate, pergroupstate,
&aggvalues[aggno], &aggnulls[aggno]);
}
/*
* Use the representative input tuple for any references to
* non-aggregated input columns in the qual and tlist.
*/
econtext->ecxt_outertuple = firstSlot;
/*
* Check the qual (HAVING clause); if the group does not match, ignore
* it and loop back to try to process another group.
*/
if (ExecQual(aggstate->ss.ps.qual, econtext, false))
{
/*
* Form and return a projection tuple using the aggregate results
* and the representative input tuple.
*/
TupleTableSlot *result;
ExprDoneCond isDone;
result = ExecProject(aggstate->ss.ps.ps_ProjInfo, &isDone);
if (isDone != ExprEndResult)
{
aggstate->ss.ps.ps_TupFromTlist =
(isDone == ExprMultipleResult);
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 peragg;
Plan *outerPlan;
ExprContext *econtext;
int numaggs,
aggno;
ListCell *l;
/* 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->aggs = NIL;
aggstate->numaggs = 0;
aggstate->eqfunctions = NULL;
aggstate->hashfunctions = NULL;
aggstate->peragg = NULL;
aggstate->agg_done = false;
aggstate->pergroup = NULL;
aggstate->grp_firstTuple = NULL;
aggstate->hashtable = NULL;
/*
* Create expression contexts. We need two, one for per-input-tuple
* processing and one for per-output-tuple processing. We cheat a little
* by using ExecAssignExprContext() to build both.
*/
ExecAssignExprContext(estate, &aggstate->ss.ps);
aggstate->tmpcontext = aggstate->ss.ps.ps_ExprContext;
ExecAssignExprContext(estate, &aggstate->ss.ps);
/*
* We also need a long-lived memory context for holding hashtable data
* structures and transition values. NOTE: the details of what is stored
* in aggcontext 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.
*/
aggstate->aggcontext =
AllocSetContextCreate(CurrentMemoryContext,
"AggContext",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
/*
* tuple table initialization
*/
ExecInitScanTupleSlot(estate, &aggstate->ss);
ExecInitResultTupleSlot(estate, &aggstate->ss.ps);
aggstate->hashslot = ExecInitExtraTupleSlot(estate);
/*
* initialize child expressions
*
* Note: ExecInitExpr finds Aggrefs for us, and also checks that no aggs
* contain other agg calls in their arguments. This would make no sense
* under SQL semantics anyway (and it's forbidden by the spec). Because
* that is true, we don't need to worry about evaluating the aggs in any
* particular order.
*/
aggstate->ss.ps.targetlist = (List *)
ExecInitExpr((Expr *) node->plan.targetlist,
(PlanState *) aggstate); aggstate->ss.ps.qual = (List *)
ExecInitExpr((Expr *) node->plan.qual,
(PlanState *) aggstate);
/*
* 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.
*/
ExecAssignScanTypeFromOuterPlan(&aggstate->ss);
/*
* Initialize result tuple type and projection info.
*/
ExecAssignResultTypeFromTL(&aggstate->ss.ps);
ExecAssignProjectionInfo(&aggstate->ss.ps, NULL);
aggstate->ss.ps.ps_TupFromTlist = false;
/*
* get the count of aggregates in targetlist and quals
*/
numaggs = aggstate->numaggs;
Assert(numaggs == list_length(aggstate->aggs));
if (numaggs <= 0)
{
/*
* This is not an error condition: we might be using the Agg node just
* to do hash-based grouping. Even in the regular case,
* constant-expression simplification could optimize away all of the
* Aggrefs in the targetlist and qual. So keep going, but force local
* copy of numaggs positive so that palloc()s below don't choke.
*/
numaggs = 1;
}
/*
* If we are grouping, precompute fmgr lookup data for inner loop. We need
* both equality and hashing functions to do it by hashing, but only
* equality if not hashing.
*/
if (node->numCols > 0)
{
if (node->aggstrategy == AGG_HASHED)
execTuplesHashPrepare(node->numCols,
node->grpOperators,
&aggstate->eqfunctions,
&aggstate->hashfunctions);
else
aggstate->eqfunctions =
execTuplesMatchPrepare(node->numCols,
node->grpOperators);
}
/*
* 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);
peragg = (AggStatePerAgg) palloc0(sizeof(AggStatePerAggData) * numaggs);
aggstate->peragg = peragg;
if (node->aggstrategy == AGG_HASHED)
{
build_hash_table(aggstate);
aggstate->table_filled = false;
/* Compute the columns we actually need to hash on */
aggstate->hash_needed = find_hash_columns(aggstate);
}
else
{
AggStatePerGroup pergroup;
pergroup = (AggStatePerGroup) palloc0(sizeof(AggStatePerGroupData) * numaggs);
aggstate->pergroup = pergroup;
}
/*
* Perform lookups of aggregate function info, and initialize the
* unchanging fields of the per-agg data. We also detect duplicate
* aggregates (for example, "SELECT sum(x) ... HAVING sum(x) > 0"). When
* duplicates are detected, we only make an AggStatePerAgg struct for the
* first one. The clones are simply pointed at the same result entry by
* giving them duplicate aggno values.
*/
aggno = -1;
foreach(l, aggstate->aggs)
{
AggrefExprState *aggrefstate = (AggrefExprState *) lfirst(l);
Aggref *aggref = (Aggref *) aggrefstate->xprstate.expr;
AggStatePerAgg peraggstate;
Oid inputTypes[FUNC_MAX_ARGS];
int numArguments;
HeapTuple aggTuple;
Form_pg_aggregate aggform;
Oid aggtranstype;
AclResult aclresult;
Oid transfn_oid,
finalfn_oid;
Expr *transfnexpr,
*finalfnexpr;
Datum textInitVal;
int i;
ListCell *lc;
/* Planner should have assigned aggregate to correct level */
Assert(aggref->agglevelsup == 0);
/* Look for a previous duplicate aggregate */
for (i = 0; i <= aggno; i++)
{
if (equal(aggref, peragg[i].aggref) &&
!contain_volatile_functions((Node *) aggref))
break;
}
if (i <= aggno)
{
/* Found a match to an existing entry, so just mark it */
aggrefstate->aggno = i;
continue;
}
/* Nope, so assign a new PerAgg record */
peraggstate = &peragg[++aggno];
/* Mark Aggref state node with assigned index in the result array */
aggrefstate->aggno = aggno;
/* Fill in the peraggstate data */
peraggstate->aggrefstate = aggrefstate;
peraggstate->aggref = aggref;
numArguments = list_length(aggref->args);
peraggstate->numArguments = numArguments;
/*
* Get actual datatypes of the inputs. These could be different from
* the agg's declared input types, when the agg accepts ANY or a
* polymorphic type.
*/
i = 0;
foreach(lc, aggref->args)
{
inputTypes[i++] = exprType((Node *) lfirst(lc));
}
aggTuple = SearchSysCache(AGGFNOID,
ObjectIdGetDatum(aggref->aggfnoid),
0, 0, 0);
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, ACL_KIND_PROC,
get_func_name(aggref->aggfnoid));
peraggstate->transfn_oid = transfn_oid = aggform->aggtransfn;
peraggstate->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
/* Check that aggregate owner has permission to call component fns */
{
HeapTuple procTuple;
Oid aggOwner;
procTuple = SearchSysCache(PROCOID,
ObjectIdGetDatum(aggref->aggfnoid),
0, 0, 0);
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, ACL_KIND_PROC,
get_func_name(transfn_oid));
if (OidIsValid(finalfn_oid))
{
aclresult = pg_proc_aclcheck(finalfn_oid, aggOwner,
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, ACL_KIND_PROC,
get_func_name(finalfn_oid));
}
}
/* resolve actual type of transition state, if polymorphic */
aggtranstype = aggform->aggtranstype;
if (IsPolymorphicType(aggtranstype))
{
/* have to fetch the agg's declared input types... */
Oid *declaredArgTypes; int agg_nargs;
(void) get_func_signature(aggref->aggfnoid,
&declaredArgTypes, &agg_nargs);
Assert(agg_nargs == numArguments);
aggtranstype = enforce_generic_type_consistency(inputTypes,
declaredArgTypes,
agg_nargs,
aggtranstype,
false);
pfree(declaredArgTypes);
}
/* build expression trees using actual argument & result types */
build_aggregate_fnexprs(inputTypes,
numArguments,
aggtranstype,
aggref->aggtype,
transfn_oid,
finalfn_oid,
&transfnexpr,
&finalfnexpr);
fmgr_info(transfn_oid, &peraggstate->transfn);
peraggstate->transfn.fn_expr = (Node *) transfnexpr;
if (OidIsValid(finalfn_oid))
{
fmgr_info(finalfn_oid, &peraggstate->finalfn);
peraggstate->finalfn.fn_expr = (Node *) finalfnexpr;
}
get_typlenbyval(aggref->aggtype,
&peraggstate->resulttypeLen,
&peraggstate->resulttypeByVal);
get_typlenbyval(aggtranstype,
&peraggstate->transtypeLen,
&peraggstate->transtypeByVal);
/*
* 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,
&peraggstate->initValueIsNull);
if (peraggstate->initValueIsNull)
peraggstate->initValue = (Datum) 0;
else
peraggstate->initValue = GetAggInitVal(textInitVal,
aggtranstype);
/*
* 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 input value as the initial
* transValue. This should have been checked at agg definition time,
* but just in case...
*/
if (peraggstate->transfn.fn_strict && peraggstate->initValueIsNull)
{
if (numArguments < 1 ||
!IsBinaryCoercible(inputTypes[0], aggtranstype))
ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("aggregate %u needs to have compatible input type and transition type",
aggref->aggfnoid)));
}
if (aggref->aggdistinct)
{
Oid lt_opr;
Oid eq_opr;
/* We don't implement DISTINCT aggs in the HASHED case */
Assert(node->aggstrategy != AGG_HASHED);
/*
* We don't currently implement DISTINCT aggs for aggs having more
* than one argument. This isn't required for anything in the SQL
* spec, but really it ought to be implemented for
* feature-completeness. FIXME someday.
*/
if (numArguments != 1)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("DISTINCT is supported only for single-argument aggregates")));
peraggstate->inputType = inputTypes[0];
get_typlenbyval(inputTypes[0],
&peraggstate->inputtypeLen,
&peraggstate->inputtypeByVal);
/*
* Look up the sorting and comparison operators to use. XXX it's
* pretty bletcherous to be making this sort of semantic decision
* in the executor. Probably the parser should decide this and
* record it in the Aggref node ... or at latest, do it in the
* planner.
*/
get_sort_group_operators(inputTypes[0],
true, true, false,
<_opr, &eq_opr, NULL);
fmgr_info(get_opcode(eq_opr), &(peraggstate->equalfn));
peraggstate->sortOperator = lt_opr;
peraggstate->sortstate = NULL;
}
ReleaseSysCache(aggTuple);
}
/* Update numaggs to match number of unique aggregates found */
aggstate->numaggs = aggno + 1;
return aggstate;
}
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;
}
void
ExecEndAgg(AggState *node)
{
PlanState *outerPlan;
int aggno;
/* Make sure we have closed any open tuplesorts */
for (aggno = 0; aggno < node->numaggs; aggno++)
{
AggStatePerAgg peraggstate = &node->peragg[aggno];
if (peraggstate->sortstate)
tuplesort_end(peraggstate->sortstate);
}
/*
* Free both the expr contexts.
*/
ExecFreeExprContext(&node->ss.ps);
node->ss.ps.ps_ExprContext = node->tmpcontext;
ExecFreeExprContext(&node->ss.ps);
/* clean up tuple table */
ExecClearTuple(node->ss.ss_ScanTupleSlot);
MemoryContextDelete(node->aggcontext);
outerPlan = outerPlanState(node);
ExecEndNode(outerPlan);
}
void
ExecReScanAgg(AggState *node, ExprContext *exprCtxt)
{
ExprContext *econtext = node->ss.ps.ps_ExprContext;
int aggno;
node->agg_done = false;
node->ss.ps.ps_TupFromTlist = false;
if (((Agg *) node->ss.ps.plan)->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, then we can just rescan the existing hash table;
* no need to build it again.
*/
if (((PlanState *) node)->lefttree->chgParam == NULL)
{
ResetTupleHashIterator(node->hashtable, &node->hashiter);
return;
}
}
/* Make sure we have closed any open tuplesorts */
for (aggno = 0; aggno < node->numaggs; aggno++)
{
AggStatePerAgg peraggstate = &node->peragg[aggno];
if (peraggstate->sortstate)
tuplesort_end(peraggstate->sortstate);
peraggstate->sortstate = NULL;
}
/* 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;
}
/* Forget current agg values */
MemSet(econtext->ecxt_aggvalues, 0, sizeof(Datum) * node->numaggs);
MemSet(econtext->ecxt_aggnulls, 0, sizeof(bool) * node->numaggs);
/*
* Release all temp storage. Note that with AGG_HASHED, the hash table is
* allocated in a sub-context of the aggcontext. We're going to rebuild
* the hash table from scratch, so we need to use
* MemoryContextResetAndDeleteChildren() to avoid leaking the old hash
* table's memory context header.
*/
MemoryContextResetAndDeleteChildren(node->aggcontext);
if (((Agg *) node->ss.ps.plan)->aggstrategy == AGG_HASHED)
{
/* Rebuild an empty hash table */
build_hash_table(node);
node->table_filled = false;
}
else
{
/*
* Reset the per-group state (in particular, mark transvalues null)
*/
MemSet(node->pergroup, 0,
sizeof(AggStatePerGroupData) * node->numaggs);
}
/*
* if chgParam of subnode is not null then plan will be re-scanned by
* first ExecProcNode.
*/
if (((PlanState *) node)->lefttree->chgParam == NULL)
ExecReScan(((PlanState *) node)->lefttree, exprCtxt);
}
/*
* 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 */
}