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postgres/src/backend/executor/nodeAgg.c
Bruce Momjian c579ce0fb0 I started adding the Having Clause and it works quite fine for 
sequential scans! (I think it will also work with hash, index, etc
but I did not check it out! I made some High level changes which
should work for all access methods, but maybe I'm wrong. Please
let me know.)

Now it is possible to make queries like:

select s.sname, max(p.pid), min(p.pid) from part p, supplier s
where s.sid=p.sid group by s.sname having max(pid)=6 and min(pid)=1
or avg(pid)=4;

Having does not work yet for queries that contain a subselect
statement in the Having clause, I'll try to fix this in the next
days.

If there are some bugs, please let me know, I'll start to read the
mailinglists now!

Now here is the patch against the original 6.3 version (no snapshot!!):

Stefan
1998-03-30 16:36:43 +00:00

714 lines
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/*-------------------------------------------------------------------------
*
* nodeAgg.c--
* Routines to handle aggregate nodes.
*
* Copyright (c) 1994, Regents of the University of California
*
*
* NOTE
* The implementation of Agg node has been reworked to handle legal
* SQL aggregates. (Do not expect POSTQUEL semantics.) -- ay 2/95
*
* IDENTIFICATION
* /usr/local/devel/pglite/cvs/src/backend/executor/nodeAgg.c,v 1.13 1995/08/01 20:19:07 jolly Exp
*
*-------------------------------------------------------------------------
*/
#include <string.h>
#include "postgres.h"
#include "fmgr.h"
#include "access/heapam.h"
#include "catalog/pg_aggregate.h"
#include "catalog/catalog.h"
#include "parser/parse_type.h"
#include "executor/executor.h"
#include "executor/nodeAgg.h"
#include "storage/bufmgr.h"
#include "utils/palloc.h"
#include "utils/syscache.h"
#include "optimizer/clauses.h"
/*
* AggFuncInfo -
* keeps the transition functions information around
*/
typedef struct AggFuncInfo
{
Oid xfn1_oid;
Oid xfn2_oid;
Oid finalfn_oid;
FmgrInfo xfn1;
FmgrInfo xfn2;
FmgrInfo finalfn;
} AggFuncInfo;
static Datum aggGetAttr(TupleTableSlot *tuple, Aggreg *agg, bool *isNull);
/* ---------------------------------------
*
* ExecAgg -
*
* ExecAgg receives tuples from its outer subplan and aggregates over
* the appropriate attribute for each (unique) aggregate in the target
* list. (The number of tuples to aggregate over depends on whether a
* GROUP BY clause is present. It might be the number of tuples in a
* group or all the tuples that satisfy the qualifications.) The value of
* each aggregate is stored in the expression context for ExecProject to
* evaluate the result tuple.
*
* ExecAgg evaluates each aggregate in the following steps: (initcond1,
* initcond2 are the initial values and sfunc1, sfunc2, and finalfunc are
* the transition functions.)
*
* value1[i] = initcond1
* value2[i] = initcond2
* forall tuples do
* value1[i] = sfunc1(aggregate_attribute, value1[i])
* value2[i] = sfunc2(value2[i])
* value1[i] = finalfunc(value1[i], value2[i])
*
* If the outer subplan is a Group node, ExecAgg returns as many tuples
* as there are groups.
*
* XXX handling of NULL doesn't work
*
* OLD COMMENTS
*
* XXX Aggregates should probably have another option: what to do
* with transfn2 if we hit a null value. "count" (transfn1 = null,
* transfn2 = increment) will want to have transfn2 called; "avg"
* (transfn1 = add, transfn2 = increment) will not. -pma 1/3/93
*
* ------------------------------------------
*/
TupleTableSlot *
ExecAgg(Agg *node)
{
AggState *aggstate;
EState *estate;
Aggreg **aggregates;
Plan *outerPlan;
int i,
nagg;
Datum *value1,
*value2;
int *noInitValue;
AggFuncInfo *aggFuncInfo;
long nTuplesAgged = 0;
ExprContext *econtext;
ProjectionInfo *projInfo;
TupleTableSlot *resultSlot;
HeapTuple oneTuple;
List *alist;
char *nulls;
bool isDone;
bool isNull = FALSE,
isNull1 = FALSE,
isNull2 = FALSE;
/***S*H***/
do {
/* ---------------------
* get state info from node
* ---------------------
*/
aggstate = node->aggstate;
if (aggstate->agg_done)
return NULL;
estate = node->plan.state;
econtext = aggstate->csstate.cstate.cs_ExprContext;
nagg = length(node->aggs);
aggregates = (Aggreg **) palloc(sizeof(Aggreg *) * nagg);
/* take List* and make it an array that can be quickly indexed */
alist = node->aggs;
for (i = 0; i < nagg; i++)
{
aggregates[i] = lfirst(alist);
aggregates[i]->aggno = i;
alist = lnext(alist);
}
value1 = node->aggstate->csstate.cstate.cs_ExprContext->ecxt_values;
nulls = node->aggstate->csstate.cstate.cs_ExprContext->ecxt_nulls;
value2 = (Datum *) palloc(sizeof(Datum) * nagg);
MemSet(value2, 0, sizeof(Datum) * nagg);
aggFuncInfo = (AggFuncInfo *) palloc(sizeof(AggFuncInfo) * nagg);
MemSet(aggFuncInfo, 0, sizeof(AggFuncInfo) * nagg);
noInitValue = (int *) palloc(sizeof(int) * nagg);
MemSet(noInitValue, 0, sizeof(noInitValue) * nagg);
outerPlan = outerPlan(node);
oneTuple = NULL;
projInfo = aggstate->csstate.cstate.cs_ProjInfo;
for (i = 0; i < nagg; i++)
{
Aggreg *agg;
char *aggname;
HeapTuple aggTuple;
Form_pg_aggregate aggp;
Oid xfn1_oid,
xfn2_oid,
finalfn_oid;
agg = aggregates[i];
/* ---------------------
* find transfer functions of all the aggregates and initialize
* their initial values
* ---------------------
*/
aggname = agg->aggname;
aggTuple = SearchSysCacheTuple(AGGNAME,
PointerGetDatum(aggname),
ObjectIdGetDatum(agg->basetype),
0, 0);
if (!HeapTupleIsValid(aggTuple))
elog(ERROR, "ExecAgg: cache lookup failed for aggregate \"%s\"(%s)",
aggname,
typeidTypeName(agg->basetype));
aggp = (Form_pg_aggregate) GETSTRUCT(aggTuple);
xfn1_oid = aggp->aggtransfn1;
xfn2_oid = aggp->aggtransfn2;
finalfn_oid = aggp->aggfinalfn;
if (OidIsValid(finalfn_oid))
{
fmgr_info(finalfn_oid, &aggFuncInfo[i].finalfn);
aggFuncInfo[i].finalfn_oid = finalfn_oid;
}
if (OidIsValid(xfn2_oid))
{
fmgr_info(xfn2_oid, &aggFuncInfo[i].xfn2);
aggFuncInfo[i].xfn2_oid = xfn2_oid;
value2[i] = (Datum) AggNameGetInitVal((char *) aggname,
aggp->aggbasetype,
2,
&isNull2);
/* ------------------------------------------
* If there is a second transition function, its initial
* value must exist -- as it does not depend on data values,
* we have no other way of determining an initial value.
* ------------------------------------------
*/
if (isNull2)
elog(ERROR, "ExecAgg: agginitval2 is null");
}
if (OidIsValid(xfn1_oid))
{
fmgr_info(xfn1_oid, &aggFuncInfo[i].xfn1);
aggFuncInfo[i].xfn1_oid = xfn1_oid;
value1[i] = (Datum) AggNameGetInitVal((char *) aggname,
aggp->aggbasetype,
1,
&isNull1);
/* ------------------------------------------
* If the initial value for the first transition function
* doesn't exist in the pg_aggregate table then we let
* the first value returned from the outer procNode become
* the initial value. (This is useful for aggregates like
* max{} and min{}.)
* ------------------------------------------
*/
if (isNull1)
{
noInitValue[i] = 1;
nulls[i] = 1;
}
}
}
/* ----------------
* for each tuple from the the outer plan, apply all the aggregates
* ----------------
*/
for (;;)
{
HeapTuple outerTuple = NULL;
TupleTableSlot *outerslot;
isNull = isNull1 = isNull2 = 0;
outerslot = ExecProcNode(outerPlan, (Plan *) node);
if (outerslot)
outerTuple = outerslot->val;
if (!HeapTupleIsValid(outerTuple))
{
/*
* when the outerplan doesn't return a single tuple, create a
* dummy heaptuple anyway because we still need to return a
* valid aggregate value. The value returned will be the
* initial values of the transition functions
*/
if (nTuplesAgged == 0)
{
TupleDesc tupType;
Datum *tupValue;
char *null_array;
tupType = aggstate->csstate.css_ScanTupleSlot->ttc_tupleDescriptor;
tupValue = projInfo->pi_tupValue;
/* initially, set all the values to NULL */
null_array = palloc(tupType->natts);
for (i = 0; i < tupType->natts; i++)
null_array[i] = 'n';
oneTuple = heap_formtuple(tupType, tupValue, null_array);
pfree(null_array);
}
break;
}
for (i = 0; i < nagg; i++)
{
AttrNumber attnum;
int2 attlen = 0;
Datum newVal = (Datum) NULL;
AggFuncInfo *aggfns = &aggFuncInfo[i];
Datum args[2];
Node *tagnode = NULL;
switch (nodeTag(aggregates[i]->target))
{
case T_Var:
tagnode = NULL;
newVal = aggGetAttr(outerslot,
aggregates[i],
&isNull);
break;
case T_Expr:
tagnode = ((Expr *) aggregates[i]->target)->oper;
econtext->ecxt_scantuple = outerslot;
newVal = ExecEvalExpr(aggregates[i]->target, econtext,
&isNull, &isDone);
break;
case T_Const:
tagnode = NULL;
econtext->ecxt_scantuple = outerslot;
newVal = ExecEvalExpr(aggregates[i]->target, econtext,
&isNull, &isDone);
break;
default:
elog(ERROR, "ExecAgg: Bad Agg->Target for Agg %d", i);
}
if (isNull && !aggregates[i]->usenulls)
continue; /* ignore this tuple for this agg */
if (aggfns->xfn1.fn_addr != NULL)
{
if (noInitValue[i])
{
int byVal = 0;
/*
* value1 and value2 has not been initialized. This is
* the first non-NULL value. We use it as the initial
* value.
*/
/*
* but we can't just use it straight, we have to make
* a copy of it since the tuple from which it came
* will be freed on the next iteration of the scan
*/
switch (nodeTag(aggregates[i]->target))
{
case T_Var:
attnum = ((Var *) aggregates[i]->target)->varattno;
attlen = outerslot->ttc_tupleDescriptor->attrs[attnum - 1]->attlen;
byVal = outerslot->ttc_tupleDescriptor->attrs[attnum - 1]->attbyval;
break;
case T_Expr:
{
FunctionCachePtr fcache_ptr;
if (nodeTag(tagnode) == T_Func)
fcache_ptr = ((Func *) tagnode)->func_fcache;
else
fcache_ptr = ((Oper *) tagnode)->op_fcache;
attlen = fcache_ptr->typlen;
byVal = fcache_ptr->typbyval;
break;
}
case T_Const:
attlen = ((Const *) aggregates[i]->target)->constlen;
byVal = ((Const *) aggregates[i]->target)->constbyval;
break;
default:
elog(ERROR, "ExecAgg: Bad Agg->Target for Agg %d", i);
}
if (attlen == -1)
{
/* variable length */
attlen = VARSIZE((struct varlena *) newVal);
}
value1[i] = (Datum) palloc(attlen);
if (byVal)
value1[i] = newVal;
else
memmove((char *) (value1[i]), (char *) newVal, attlen);
noInitValue[i] = 0;
nulls[i] = 0;
}
else
{
/*
* apply the transition functions.
*/
args[0] = value1[i];
args[1] = newVal;
value1[i] =
(Datum) fmgr_c(&aggfns->xfn1,
(FmgrValues *) args,
&isNull1);
Assert(!isNull1);
}
}
if (aggfns->xfn2.fn_addr != NULL)
{
Datum xfn2_val = value2[i];
value2[i] =
(Datum) fmgr_c(&aggfns->xfn2,
(FmgrValues *) &xfn2_val, &isNull2);
Assert(!isNull2);
}
}
/*
* keep this for the projection (we only need one of these - all
* the tuples we aggregate over share the same group column)
*/
if (!oneTuple)
{
oneTuple = heap_copytuple(outerslot->val);
}
nTuplesAgged++;
}
/* --------------
* finalize the aggregate (if necessary), and get the resultant value
* --------------
*/
for (i = 0; i < nagg; i++)
{
char *args[2];
AggFuncInfo *aggfns = &aggFuncInfo[i];
if (noInitValue[i])
{
/*
* No values found for this agg; return current state. This
* seems to fix behavior for avg() aggregate. -tgl 12/96
*/
}
else if (aggfns->finalfn.fn_addr != NULL && nTuplesAgged > 0)
{
if (aggfns->finalfn.fn_nargs > 1)
{
args[0] = (char *) value1[i];
args[1] = (char *) value2[i];
}
else if (aggfns->xfn1.fn_addr != NULL)
{
args[0] = (char *) value1[i];
}
else if (aggfns->xfn2.fn_addr != NULL)
{
args[0] = (char *) value2[i];
}
else
elog(NOTICE, "ExecAgg: no valid transition functions??");
value1[i] = (Datum) fmgr_c(&aggfns->finalfn,
(FmgrValues *) args, &(nulls[i]));
}
else if (aggfns->xfn1.fn_addr != NULL)
{
/*
* value in the right place, ignore. (If you remove this case,
* fix the else part. -ay 2/95)
*/
}
else if (aggfns->xfn2.fn_addr != NULL)
{
value1[i] = value2[i];
}
else
elog(ERROR, "ExecAgg: no valid transition functions??");
}
/*
* whether the aggregation is done depends on whether we are doing
* aggregation over groups or the entire table
*/
if (nodeTag(outerPlan) == T_Group)
{
/* aggregation over groups */
aggstate->agg_done = ((Group *) outerPlan)->grpstate->grp_done;
}
else
{
aggstate->agg_done = TRUE;
}
/* ----------------
* form a projection tuple, store it in the result tuple
* slot and return it.
* ----------------
*/
/***S*H***/
}
while((ExecQual(fix_opids(node->plan.qual),econtext)!=true) &&
(node->plan.qual!=NULL));
ExecStoreTuple(oneTuple,
aggstate->csstate.css_ScanTupleSlot,
InvalidBuffer,
false);
econtext->ecxt_scantuple = aggstate->csstate.css_ScanTupleSlot;
resultSlot = ExecProject(projInfo, &isDone);
if (oneTuple)
pfree(oneTuple);
return resultSlot;
}
/* -----------------
* ExecInitAgg
*
* Creates the run-time information for the agg node produced by the
* planner and initializes its outer subtree
* -----------------
*/
bool
ExecInitAgg(Agg *node, EState *estate, Plan *parent)
{
AggState *aggstate;
Plan *outerPlan;
ExprContext *econtext;
/*
* assign the node's execution state
*/
node->plan.state = estate;
/*
* create state structure
*/
aggstate = makeNode(AggState);
node->aggstate = aggstate;
aggstate->agg_done = FALSE;
/*
* assign node's base id and create expression context
*/
ExecAssignNodeBaseInfo(estate, &aggstate->csstate.cstate,
(Plan *) parent);
ExecAssignExprContext(estate, &aggstate->csstate.cstate);
#define AGG_NSLOTS 2
/*
* tuple table initialization
*/
ExecInitScanTupleSlot(estate, &aggstate->csstate);
ExecInitResultTupleSlot(estate, &aggstate->csstate.cstate);
econtext = aggstate->csstate.cstate.cs_ExprContext;
econtext->ecxt_values =
(Datum *) palloc(sizeof(Datum) * length(node->aggs));
MemSet(econtext->ecxt_values, 0, sizeof(Datum) * length(node->aggs));
econtext->ecxt_nulls = (char *) palloc(length(node->aggs));
MemSet(econtext->ecxt_nulls, 0, length(node->aggs));
/*
* initializes child nodes
*/
outerPlan = outerPlan(node);
ExecInitNode(outerPlan, estate, (Plan *) node);
/*
* Result runs in its own context, but make it use our aggregates fix
* for 'select sum(2+2)'
*/
if (nodeTag(outerPlan) == T_Result)
{
((Result *) outerPlan)->resstate->cstate.cs_ProjInfo->pi_exprContext->ecxt_values =
econtext->ecxt_values;
((Result *) outerPlan)->resstate->cstate.cs_ProjInfo->pi_exprContext->ecxt_nulls =
econtext->ecxt_nulls;
}
/* ----------------
* initialize tuple type.
* ----------------
*/
ExecAssignScanTypeFromOuterPlan((Plan *) node, &aggstate->csstate);
/*
* Initialize tuple type for both result and scan. This node does no
* projection
*/
ExecAssignResultTypeFromTL((Plan *) node, &aggstate->csstate.cstate);
ExecAssignProjectionInfo((Plan *) node, &aggstate->csstate.cstate);
return TRUE;
}
int
ExecCountSlotsAgg(Agg *node)
{
return ExecCountSlotsNode(outerPlan(node)) +
ExecCountSlotsNode(innerPlan(node)) +
AGG_NSLOTS;
}
/* ------------------------
* ExecEndAgg(node)
*
* -----------------------
*/
void
ExecEndAgg(Agg *node)
{
AggState *aggstate;
Plan *outerPlan;
aggstate = node->aggstate;
ExecFreeProjectionInfo(&aggstate->csstate.cstate);
outerPlan = outerPlan(node);
ExecEndNode(outerPlan, (Plan *) node);
/* clean up tuple table */
ExecClearTuple(aggstate->csstate.css_ScanTupleSlot);
}
/*****************************************************************************
* Support Routines
*****************************************************************************/
/*
* aggGetAttr -
* get the attribute (specified in the Var node in agg) to aggregate
* over from the tuple
*/
static Datum
aggGetAttr(TupleTableSlot *slot,
Aggreg *agg,
bool *isNull)
{
Datum result;
AttrNumber attnum;
HeapTuple heapTuple;
TupleDesc tuple_type;
Buffer buffer;
/* ----------------
* extract tuple information from the slot
* ----------------
*/
heapTuple = slot->val;
tuple_type = slot->ttc_tupleDescriptor;
buffer = slot->ttc_buffer;
attnum = ((Var *) agg->target)->varattno;
/*
* If the attribute number is invalid, then we are supposed to return
* the entire tuple, we give back a whole slot so that callers know
* what the tuple looks like.
*/
if (attnum == InvalidAttrNumber)
{
TupleTableSlot *tempSlot;
TupleDesc td;
HeapTuple tup;
tempSlot = makeNode(TupleTableSlot);
tempSlot->ttc_shouldFree = false;
tempSlot->ttc_descIsNew = true;
tempSlot->ttc_tupleDescriptor = (TupleDesc) NULL,
tempSlot->ttc_buffer = InvalidBuffer;
tempSlot->ttc_whichplan = -1;
tup = heap_copytuple(slot->val);
td = CreateTupleDescCopy(slot->ttc_tupleDescriptor);
ExecSetSlotDescriptor(tempSlot, td);
ExecStoreTuple(tup, tempSlot, InvalidBuffer, true);
return (Datum) tempSlot;
}
result =
heap_getattr(heapTuple, /* tuple containing attribute */
attnum, /* attribute number of desired attribute */
tuple_type,/* tuple descriptor of tuple */
isNull); /* return: is attribute null? */
/* ----------------
* return null if att is null
* ----------------
*/
if (*isNull)
return (Datum) NULL;
return result;
}
void
ExecReScanAgg(Agg *node, ExprContext *exprCtxt, Plan *parent)
{
AggState *aggstate = node->aggstate;
ExprContext *econtext = aggstate->csstate.cstate.cs_ExprContext;
aggstate->agg_done = FALSE;
MemSet(econtext->ecxt_values, 0, sizeof(Datum) * length(node->aggs));
MemSet(econtext->ecxt_nulls, 0, length(node->aggs));
/*
* if chgParam of subnode is not null then plan will be re-scanned by
* first ExecProcNode.
*/
if (((Plan *) node)->lefttree->chgParam == NULL)
ExecReScan(((Plan *) node)->lefttree, exprCtxt, (Plan *) node);
}
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