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Teach nodeSort and nodeMaterial to optimize out unnecessary overhead

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when the passed-down eflags indicate they can.
Simon Riggs and Tom Lane
This commit is contained in:
Tom Lane
2006-02-28 05:48:44 +00:00
parent 2c0ef9777c
commit d2c555ee53
3 changed files with 80 additions and 31 deletions
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83
src/backend/executor/nodeMaterial.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeMaterial.c,v 1.52 2006/02/28 04:10:27 tgl Exp $
* $PostgreSQL: pgsql/src/backend/executor/nodeMaterial.c,v 1.53 2006/02/28 05:48:44 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -58,9 +58,9 @@ ExecMaterial(MaterialState *node)
tuplestorestate = (Tuplestorestate *) node->tuplestorestate;
/*
* If first time through, initialize the tuplestore.
* If first time through, and we need a tuplestore, initialize it.
*/
if (tuplestorestate == NULL)
if (tuplestorestate == NULL && node->randomAccess)
{
tuplestorestate = tuplestore_begin_heap(true, false, work_mem);
@ -71,7 +71,8 @@ ExecMaterial(MaterialState *node)
* If we are not at the end of the tuplestore, or are going backwards, try
* to fetch a tuple from tuplestore.
*/
eof_tuplestore = tuplestore_ateof(tuplestorestate);
eof_tuplestore = (tuplestorestate == NULL) ||
tuplestore_ateof(tuplestorestate);
if (!forward && eof_tuplestore)
{
@ -135,7 +136,8 @@ ExecMaterial(MaterialState *node)
* tuplestore is certainly in EOF state, its read position will move
* forward over the added tuple. This is what we want.
*/
tuplestore_puttuple(tuplestorestate, (void *) heapTuple);
if (tuplestorestate)
tuplestore_puttuple(tuplestorestate, (void *) heapTuple);
}
/*
@ -165,8 +167,18 @@ ExecInitMaterial(Material *node, EState *estate, int eflags)
matstate->ss.ps.plan = (Plan *) node;
matstate->ss.ps.state = estate;
matstate->tuplestorestate = NULL;
/*
* We must have random access to the subplan output to do backward scan
* or mark/restore. We also prefer to materialize the subplan output
* if we might be called on to rewind and replay it many times.
* However, if none of these cases apply, we can skip storing the data.
*/
matstate->randomAccess = (eflags & (EXEC_FLAG_REWIND |
EXEC_FLAG_BACKWARD |
EXEC_FLAG_MARK)) != 0;
matstate->eof_underlying = false;
matstate->tuplestorestate = NULL;
/*
* Miscellaneous initialization
@ -249,6 +261,8 @@ ExecEndMaterial(MaterialState *node)
void
ExecMaterialMarkPos(MaterialState *node)
{
Assert(node->randomAccess);
/*
* if we haven't materialized yet, just return.
*/
@ -267,6 +281,8 @@ ExecMaterialMarkPos(MaterialState *node)
void
ExecMaterialRestrPos(MaterialState *node)
{
Assert(node->randomAccess);
/*
* if we haven't materialized yet, just return.
*/
@ -288,29 +304,44 @@ ExecMaterialRestrPos(MaterialState *node)
void
ExecMaterialReScan(MaterialState *node, ExprContext *exprCtxt)
{
/*
* If we haven't materialized yet, just return. If outerplan' chgParam is
* not NULL then it will be re-scanned by ExecProcNode, else - no reason
* to re-scan it at all.
*/
if (!node->tuplestorestate)
return;
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
/*
* If subnode is to be rescanned then we forget previous stored results;
* we have to re-read the subplan and re-store.
*
* Otherwise we can just rewind and rescan the stored output. The state of
* the subnode does not change.
*/
if (((PlanState *) node)->lefttree->chgParam != NULL)
if (node->randomAccess)
{
tuplestore_end((Tuplestorestate *) node->tuplestorestate);
node->tuplestorestate = NULL;
node->eof_underlying = false;
/*
* If we haven't materialized yet, just return. If outerplan' chgParam
* is not NULL then it will be re-scanned by ExecProcNode, else - no
* reason to re-scan it at all.
*/
if (!node->tuplestorestate)
return;
/*
* If subnode is to be rescanned then we forget previous stored
* results; we have to re-read the subplan and re-store.
*
* Otherwise we can just rewind and rescan the stored output. The
* state of the subnode does not change.
*/
if (((PlanState *) node)->lefttree->chgParam != NULL)
{
tuplestore_end((Tuplestorestate *) node->tuplestorestate);
node->tuplestorestate = NULL;
node->eof_underlying = false;
}
else
tuplestore_rescan((Tuplestorestate *) node->tuplestorestate);
}
else
tuplestore_rescan((Tuplestorestate *) node->tuplestorestate);
{
/* In this case we are just passing on the subquery's output */
/*
* 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);
node->eof_underlying = false;
}
}