diff options
Diffstat (limited to 'src/backend/executor/nodeAgg.c')
| -rw-r--r-- | src/backend/executor/nodeAgg.c | 336 |
1 files changed, 199 insertions, 137 deletions
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c index bf4a9bbbdaa..7714a680909 100644 --- a/src/backend/executor/nodeAgg.c +++ b/src/backend/executor/nodeAgg.c @@ -46,7 +46,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/executor/nodeAgg.c,v 1.90 2002/11/01 19:33:09 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/executor/nodeAgg.c,v 1.91 2002/11/06 00:00:43 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -58,6 +58,7 @@ #include "catalog/pg_operator.h" #include "executor/executor.h" #include "executor/nodeAgg.h" +#include "executor/nodeGroup.h" #include "miscadmin.h" #include "optimizer/clauses.h" #include "parser/parse_coerce.h" @@ -159,6 +160,7 @@ typedef struct AggStatePerAggData static void initialize_aggregate(AggStatePerAgg peraggstate); static void advance_transition_function(AggStatePerAgg peraggstate, Datum newVal, bool isNull); +static void advance_aggregates(AggState *aggstate, ExprContext *econtext); static void process_sorted_aggregate(AggState *aggstate, AggStatePerAgg peraggstate); static void finalize_aggregate(AggStatePerAgg peraggstate, @@ -314,6 +316,62 @@ advance_transition_function(AggStatePerAgg peraggstate, } /* + * Advance all the aggregates for one input tuple. The input tuple + * has been stored in econtext->ecxt_scantuple, so that it is accessible + * to ExecEvalExpr. + * + * When called, CurrentMemoryContext should be the per-query context. + */ +static void +advance_aggregates(AggState *aggstate, ExprContext *econtext) +{ + MemoryContext oldContext; + int aggno; + + /* + * Clear and select the current working context for evaluation + * of the input expressions and transition functions at this + * input tuple. + */ + econtext->ecxt_per_tuple_memory = aggstate->agg_cxt[aggstate->which_cxt]; + ResetExprContext(econtext); + oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory); + + for (aggno = 0; aggno < aggstate->numaggs; aggno++) + { + AggStatePerAgg peraggstate = &aggstate->peragg[aggno]; + Aggref *aggref = peraggstate->aggref; + Datum newVal; + bool isNull; + + newVal = ExecEvalExpr(aggref->target, econtext, &isNull, NULL); + + if (aggref->aggdistinct) + { + /* in DISTINCT mode, we may ignore nulls */ + if (isNull) + continue; + /* putdatum has to be called in per-query context */ + MemoryContextSwitchTo(oldContext); + tuplesort_putdatum(peraggstate->sortstate, newVal, isNull); + MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory); + } + else + { + advance_transition_function(peraggstate, newVal, isNull); + } + } + + /* + * Make the other context current so that these transition + * results are preserved. + */ + aggstate->which_cxt = 1 - aggstate->which_cxt; + + MemoryContextSwitchTo(oldContext); +} + +/* * 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, @@ -448,23 +506,18 @@ finalize_aggregate(AggStatePerAgg peraggstate, } -/* --------------------------------------- - * +/* * 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 a GROUP BY clause is - * present. We can produce an aggregate result row per group, or just - * one for the whole query. The value of each aggregate is stored in - * the expression context to be used when ExecProject evaluates the - * result tuple. - * - * If the outer subplan is a Group node, ExecAgg returns as many tuples - * as there are groups. - * - * ------------------------------------------ + * 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(Agg *node) @@ -478,10 +531,10 @@ ExecAgg(Agg *node) bool *aggnulls; AggStatePerAgg peragg; MemoryContext oldContext; + TupleTableSlot *outerslot; + TupleTableSlot *firstSlot; TupleTableSlot *resultSlot; - HeapTuple inputTuple; int aggno; - bool isNull; /* * get state info from node @@ -494,6 +547,7 @@ ExecAgg(Agg *node) aggnulls = econtext->ecxt_aggnulls; projInfo = aggstate->csstate.cstate.cs_ProjInfo; peragg = aggstate->peragg; + firstSlot = aggstate->csstate.css_ScanTupleSlot; /* * We loop retrieving groups until we find one matching @@ -505,6 +559,31 @@ ExecAgg(Agg *node) return NULL; /* + * 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, (Plan *) node); + 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 = heap_copytuple(outerslot->val); + } + 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 */ MemoryContextReset(aggstate->tup_cxt); @@ -519,74 +598,61 @@ ExecAgg(Agg *node) initialize_aggregate(peraggstate); } - inputTuple = NULL; /* no saved input tuple yet */ - - /* - * for each tuple from the outer plan, update all the aggregates - */ - for (;;) + if (aggstate->grp_firstTuple != NULL) { - TupleTableSlot *outerslot; + /* + * 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 */ - outerslot = ExecProcNode(outerPlan, (Plan *) node); - if (TupIsNull(outerslot)) - break; - econtext->ecxt_scantuple = outerslot; + /* set up for first advance_aggregates call */ + econtext->ecxt_scantuple = firstSlot; /* - * Clear and select the current working context for evaluation - * of the input expressions and transition functions at this - * input tuple. + * Process each outer-plan tuple, and then fetch the next one, + * until we exhaust the outer plan or cross a group boundary. */ - econtext->ecxt_per_tuple_memory = - aggstate->agg_cxt[aggstate->which_cxt]; - ResetExprContext(econtext); - oldContext = - MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory); - - for (aggno = 0; aggno < aggstate->numaggs; aggno++) + for (;;) { - AggStatePerAgg peraggstate = &peragg[aggno]; - Aggref *aggref = peraggstate->aggref; - Datum newVal; - - newVal = ExecEvalExpr(aggref->target, econtext, - &isNull, NULL); + advance_aggregates(aggstate, econtext); - if (aggref->aggdistinct) + outerslot = ExecProcNode(outerPlan, (Plan *) node); + if (TupIsNull(outerslot)) { - /* in DISTINCT mode, we may ignore nulls */ - if (isNull) - continue; - /* putdatum has to be called in per-query context */ - MemoryContextSwitchTo(oldContext); - tuplesort_putdatum(peraggstate->sortstate, - newVal, isNull); - MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory); + /* no more outer-plan tuples available */ + aggstate->agg_done = true; + break; } - else + /* set up for next advance_aggregates call */ + econtext->ecxt_scantuple = outerslot; + + /* + * If we are grouping, check whether we've crossed a group + * boundary. + */ + if (node->aggstrategy == AGG_SORTED) { - advance_transition_function(peraggstate, - newVal, isNull); + if (!execTuplesMatch(firstSlot->val, + outerslot->val, + firstSlot->ttc_tupleDescriptor, + node->numCols, node->grpColIdx, + aggstate->eqfunctions, + aggstate->agg_cxt[aggstate->which_cxt])) + { + /* + * Save the first input tuple of the next group. + */ + aggstate->grp_firstTuple = heap_copytuple(outerslot->val); + break; + } } } - - /* - * Make the other context current so that these transition - * results are preserved. - */ - aggstate->which_cxt = 1 - aggstate->which_cxt; - - MemoryContextSwitchTo(oldContext); - - /* - * Keep a copy of the first input tuple for the projection. - * (We only need one since only the GROUP BY columns in it can - * be referenced, and these will be the same for all tuples - * aggregated over.) - */ - if (!inputTuple) - inputTuple = heap_copytuple(outerslot->val); } /* @@ -626,78 +692,51 @@ ExecAgg(Agg *node) } /* - * If the outerPlan is a Group node, we will reach here after each - * group. We are not done unless the Group node is done (a little - * ugliness here while we reach into the Group's state to find - * out). Furthermore, when grouping we return nothing at all - * unless we had some input tuple(s). By the nature of Group, - * there are no empty groups, so if we get here with no input the - * whole scan is empty. + * If we have no first tuple (ie, the outerPlan didn't return + * anything), create a dummy all-nulls input tuple for use by + * ExecProject. 99.44% of the time this is a waste of cycles, + * because ordinarily the projected output tuple's targetlist + * cannot contain any direct (non-aggregated) references to + * input columns, so the dummy tuple will not be referenced. + * However there are special cases where this isn't so --- in + * particular an UPDATE involving an aggregate will have a + * targetlist reference to ctid. We need to return a null for + * ctid in that situation, not coredump. * - * If the outerPlan isn't a Group, we are done when we get here, and - * we will emit a (single) tuple even if there were no input - * tuples. + * The values returned for the aggregates will be the initial + * values of the transition functions. */ - if (IsA(outerPlan, Group)) + if (TupIsNull(firstSlot)) { - /* aggregation over groups */ - aggstate->agg_done = ((Group *) outerPlan)->grpstate->grp_done; - /* check for no groups */ - if (inputTuple == NULL) - return NULL; - } - else - { - aggstate->agg_done = true; + TupleDesc tupType; - /* - * If inputtuple==NULL (ie, the outerPlan didn't return - * anything), create a dummy all-nulls input tuple for use by - * ExecProject. 99.44% of the time this is a waste of cycles, - * because ordinarily the projected output tuple's targetlist - * cannot contain any direct (non-aggregated) references to - * input columns, so the dummy tuple will not be referenced. - * However there are special cases where this isn't so --- in - * particular an UPDATE involving an aggregate will have a - * targetlist reference to ctid. We need to return a null for - * ctid in that situation, not coredump. - * - * The values returned for the aggregates will be the initial - * values of the transition functions. - */ - if (inputTuple == NULL) + /* Should only happen in non-grouped mode */ + Assert(node->aggstrategy == AGG_PLAIN); + Assert(aggstate->agg_done); + + tupType = firstSlot->ttc_tupleDescriptor; + /* watch out for zero-column input tuples, though... */ + if (tupType && tupType->natts > 0) { - TupleDesc tupType; + HeapTuple nullsTuple; Datum *dvalues; char *dnulls; - tupType = aggstate->csstate.css_ScanTupleSlot->ttc_tupleDescriptor; - /* watch out for null input tuples, though... */ - if (tupType && tupType->natts > 0) - { - dvalues = (Datum *) palloc(sizeof(Datum) * tupType->natts); - dnulls = (char *) palloc(sizeof(char) * tupType->natts); - MemSet(dvalues, 0, sizeof(Datum) * tupType->natts); - MemSet(dnulls, 'n', sizeof(char) * tupType->natts); - inputTuple = heap_formtuple(tupType, dvalues, dnulls); - pfree(dvalues); - pfree(dnulls); - } + dvalues = (Datum *) palloc(sizeof(Datum) * tupType->natts); + dnulls = (char *) palloc(sizeof(char) * tupType->natts); + MemSet(dvalues, 0, sizeof(Datum) * tupType->natts); + MemSet(dnulls, 'n', sizeof(char) * tupType->natts); + nullsTuple = heap_formtuple(tupType, dvalues, dnulls); + ExecStoreTuple(nullsTuple, + firstSlot, + InvalidBuffer, + true); + pfree(dvalues); + pfree(dnulls); } } /* - * Store the representative input tuple in the tuple table slot - * reserved for it. The tuple will be deleted when it is cleared - * from the slot. - */ - ExecStoreTuple(inputTuple, - aggstate->csstate.css_ScanTupleSlot, - InvalidBuffer, - true); - econtext->ecxt_scantuple = aggstate->csstate.css_ScanTupleSlot; - - /* * Do projection and qual check in the per-output-tuple context. */ econtext->ecxt_per_tuple_memory = aggstate->tup_cxt; @@ -707,6 +746,7 @@ ExecAgg(Agg *node) * representative input tuple. Store it in the result tuple slot. * Note we do not support aggregates returning sets ... */ + econtext->ecxt_scantuple = firstSlot; resultSlot = ExecProject(projInfo, NULL); /* @@ -748,6 +788,8 @@ ExecInitAgg(Agg *node, EState *estate, Plan *parent) */ aggstate = makeNode(AggState); node->aggstate = aggstate; + aggstate->eqfunctions = NULL; + aggstate->grp_firstTuple = NULL; aggstate->agg_done = false; /* @@ -765,13 +807,12 @@ ExecInitAgg(Agg *node, EState *estate, Plan *parent) if (numaggs <= 0) { /* - * This used to be treated as an error, but we can't do that - * anymore because constant-expression simplification could - * optimize away all of the Aggrefs in the targetlist and qual. - * So, just make a debug note, and force numaggs positive so that - * palloc()s below don't choke. + * 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. */ - elog(DEBUG1, "ExecInitAgg: could not find any aggregate functions"); numaggs = 1; } @@ -844,6 +885,17 @@ ExecInitAgg(Agg *node, EState *estate, Plan *parent) ExecAssignProjectionInfo((Plan *) node, &aggstate->csstate.cstate); /* + * If we are grouping, precompute fmgr lookup data for inner loop + */ + if (node->numCols > 0) + { + aggstate->eqfunctions = + execTuplesMatchPrepare(ExecGetScanType(&aggstate->csstate), + node->numCols, + node->grpColIdx); + } + + /* * Perform lookups of aggregate function info, and initialize the * unchanging fields of the per-agg data */ @@ -1024,6 +1076,11 @@ ExecEndAgg(Agg *node) /* clean up tuple table */ ExecClearTuple(aggstate->csstate.css_ScanTupleSlot); + if (aggstate->grp_firstTuple != NULL) + { + heap_freetuple(aggstate->grp_firstTuple); + aggstate->grp_firstTuple = NULL; + } } void @@ -1033,6 +1090,11 @@ ExecReScanAgg(Agg *node, ExprContext *exprCtxt, Plan *parent) ExprContext *econtext = aggstate->csstate.cstate.cs_ExprContext; aggstate->agg_done = false; + if (aggstate->grp_firstTuple != NULL) + { + heap_freetuple(aggstate->grp_firstTuple); + aggstate->grp_firstTuple = NULL; + } MemSet(econtext->ecxt_aggvalues, 0, sizeof(Datum) * aggstate->numaggs); MemSet(econtext->ecxt_aggnulls, 0, sizeof(bool) * aggstate->numaggs); |