greenplumn nodeResult 源码
greenplumn nodeResult 代码
文件路径:/src/backend/executor/nodeResult.c
/*-------------------------------------------------------------------------
*
* nodeResult.c
* support for constant nodes needing special code.
*
* DESCRIPTION
*
* Result nodes are used in queries where no relations are scanned.
* Examples of such queries are:
*
* select 1 * 2
*
* insert into emp values ('mike', 15000)
*
* (Remember that in an INSERT or UPDATE, we need a plan tree that
* generates the new rows.)
*
* Result nodes are also used to optimise queries with constant
* qualifications (ie, quals that do not depend on the scanned data),
* such as:
*
* select * from emp where 2 > 1
*
* In this case, the plan generated is
*
* Result (with 2 > 1 qual)
* /
* SeqScan (emp.*)
*
* At runtime, the Result node evaluates the constant qual once,
* which is shown by EXPLAIN as a One-Time Filter. If it's
* false, we can return an empty result set without running the
* controlled plan at all. If it's true, we run the controlled
* plan normally and pass back the results.
*
*
* Portions Copyright (c) 2005-2008, Greenplum inc.
* Portions Copyright (c) 2012-Present VMware, Inc. or its affiliates.
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/executor/nodeResult.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "executor/executor.h"
#include "executor/nodeResult.h"
#include "miscadmin.h"
#include "utils/memutils.h"
#include "cdb/cdbhash.h"
#include "cdb/cdbutil.h"
#include "cdb/cdbvars.h"
#include "cdb/memquota.h"
#include "executor/spi.h"
static bool TupleMatchesHashFilter(ResultState *node, TupleTableSlot *resultSlot);
/* ----------------------------------------------------------------
* ExecResult(node)
*
* returns the tuples from the outer plan which satisfy the
* qualification clause. Since result nodes with right
* subtrees are never planned, we ignore the right subtree
* entirely (for now).. -cim 10/7/89
*
* The qualification containing only constant clauses are
* checked first before any processing is done. It always returns
* 'nil' if the constant qualification is not satisfied.
* ----------------------------------------------------------------
*/
static TupleTableSlot *
ExecResult(PlanState *pstate)
{
ResultState *node = castNode(ResultState, pstate);
TupleTableSlot *outerTupleSlot;
PlanState *outerPlan;
ExprContext *econtext;
CHECK_FOR_INTERRUPTS();
econtext = node->ps.ps_ExprContext;
/*
* check constant qualifications like (2 > 1), if not already done
*/
if (node->rs_checkqual)
{
bool qualResult = ExecQual(node->resconstantqual, econtext);
node->rs_checkqual = false;
if (!qualResult)
{
node->rs_done = true;
return NULL;
}
}
/*
* Reset per-tuple memory context to free any expression evaluation
* storage allocated in the previous tuple cycle.
*/
ResetExprContext(econtext);
/*
* if rs_done is true then it means that we were asked to return a
* constant tuple and we already did the last time ExecResult() was
* called, OR that we failed the constant qual check. Either way, now we
* are through.
*/
while (!node->rs_done)
{
outerPlan = outerPlanState(node);
if (outerPlan != NULL)
{
/*
* retrieve tuples from the outer plan until there are no more.
*/
outerTupleSlot = ExecProcNode(outerPlan);
if (TupIsNull(outerTupleSlot))
return NULL;
/*
* prepare to compute projection expressions, which will expect to
* access the input tuples as varno OUTER.
*/
econtext->ecxt_outertuple = outerTupleSlot;
/*
* GPDB: if there's a non-constant qual, check that too.
*
* PostgreSQL also initializes node->ps.qual in ExecInitResult,
* but it's not used for anything. But GPDB can create Results
* with quals, see create_projection_path_with_quals().
*/
if (node->ps.qual && !ExecQualAndReset(node->ps.qual, econtext))
continue;
}
else
{
/*
* if we don't have an outer plan, then we are just generating the
* results from a constant target list. Do it only once.
*/
node->rs_done = true;
}
/* form the result tuple using ExecProject(), and return it */
TupleTableSlot *candidateOutputSlot;
candidateOutputSlot = ExecProject(node->ps.ps_ProjInfo);
/*
* If there was a GPDB hash filter, check that too. Note that
* the hash filter is expressed in terms of *result* slot, so
* we must do this after projecting.
*/
if (!TupleMatchesHashFilter(node, candidateOutputSlot))
continue;
return candidateOutputSlot;
}
return NULL;
}
/**
* Returns true if tuple matches hash filter.
*/
static bool
TupleMatchesHashFilter(ResultState *node, TupleTableSlot *resultSlot)
{
Result *resultNode = (Result *)node->ps.plan;
bool res = true;
Assert(resultNode);
Assert(!TupIsNull(resultSlot));
if (node->hashFilter)
{
int i;
cdbhashinit(node->hashFilter);
for (i = 0; i < resultNode->numHashFilterCols; i++)
{
int attnum = resultNode->hashFilterColIdx[i];
Datum hAttr;
bool isnull;
hAttr = slot_getattr(resultSlot, attnum, &isnull);
cdbhash(node->hashFilter, i + 1, hAttr, isnull);
}
int targetSeg = cdbhashreduce(node->hashFilter);
res = (targetSeg == GpIdentity.segindex);
}
return res;
}
/* ----------------------------------------------------------------
* ExecResultMarkPos
* ----------------------------------------------------------------
*/
void
ExecResultMarkPos(ResultState *node)
{
PlanState *outerPlan = outerPlanState(node);
if (outerPlan != NULL)
ExecMarkPos(outerPlan);
else
elog(DEBUG2, "Result nodes do not support mark/restore");
}
/* ----------------------------------------------------------------
* ExecResultRestrPos
* ----------------------------------------------------------------
*/
void
ExecResultRestrPos(ResultState *node)
{
PlanState *outerPlan = outerPlanState(node);
if (outerPlan != NULL)
ExecRestrPos(outerPlan);
else
elog(ERROR, "Result nodes do not support mark/restore");
}
/* ----------------------------------------------------------------
* ExecInitResult
*
* Creates the run-time state information for the result node
* produced by the planner and initializes outer relations
* (child nodes).
* ----------------------------------------------------------------
*/
ResultState *
ExecInitResult(Result *node, EState *estate, int eflags)
{
ResultState *resstate;
/* check for unsupported flags */
Assert(!(eflags & (EXEC_FLAG_MARK | EXEC_FLAG_BACKWARD)) ||
outerPlan(node) != NULL);
/*
* create state structure
*/
resstate = makeNode(ResultState);
resstate->ps.plan = (Plan *) node;
resstate->ps.state = estate;
resstate->ps.ExecProcNode = ExecResult;
resstate->rs_done = false;
resstate->rs_checkqual = (node->resconstantqual == NULL) ? false : true;
/*
* Miscellaneous initialization
*
* create expression context for node
*/
ExecAssignExprContext(estate, &resstate->ps);
/*
* initialize child nodes
*/
outerPlanState(resstate) = ExecInitNode(outerPlan(node), estate, eflags);
/*
* we don't use inner plan
*/
Assert(innerPlan(node) == NULL);
/*
* Initialize result slot, type and projection.
*/
ExecInitResultTupleSlotTL(&resstate->ps, &TTSOpsVirtual);
ExecAssignProjectionInfo(&resstate->ps, NULL);
/*
* initialize child expressions
*/
resstate->ps.qual =
ExecInitQual(node->plan.qual, (PlanState *) resstate);
resstate->resconstantqual =
ExecInitQual((List *) node->resconstantqual, (PlanState *) resstate);
/*
* initialize hash filter
*/
if (node->numHashFilterCols > 0)
{
int currentSliceId = estate->currentSliceId;
ExecSlice *currentSlice = &estate->es_sliceTable->slices[currentSliceId];
resstate->hashFilter = makeCdbHash(currentSlice->planNumSegments,
node->numHashFilterCols,
node->hashFilterFuncs);
}
if (!IsResManagerMemoryPolicyNone()
&& IsResultMemoryIntensive(node))
{
SPI_ReserveMemory(((Plan *)node)->operatorMemKB * 1024L);
}
return resstate;
}
/* ----------------------------------------------------------------
* ExecEndResult
*
* frees up storage allocated through C routines
* ----------------------------------------------------------------
*/
void
ExecEndResult(ResultState *node)
{
/*
* Free the exprcontext
*/
ExecFreeExprContext(&node->ps);
/*
* clean out the tuple table
*/
ExecClearTuple(node->ps.ps_ResultTupleSlot);
/*
* shut down subplans
*/
ExecEndNode(outerPlanState(node));
}
void
ExecReScanResult(ResultState *node)
{
node->rs_done = false;
node->rs_checkqual = (node->resconstantqual == NULL) ? false : true;
/*
* If chgParam of subnode is not null then plan will be re-scanned by
* first ExecProcNode.
*/
if (node->ps.lefttree &&
node->ps.lefttree->chgParam == NULL)
ExecReScan(node->ps.lefttree);
}
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