/*
* ExecAssignScanProjectionInfo
* Set up projection info for a scan node, if necessary.
*
* We can avoid a projection step if the requested tlist exactly matches
* the underlying tuple type. If so, we just set ps_ProjInfo to NULL.
* Note that this case occurs not only for simple "SELECT * FROM ...", but
* also in most cases where there are joins or other processing nodes above
* the scan node, because the planner will preferentially generate a matching
* tlist.
*
* ExecAssignScanType must have been called already.
*/
void
ExecAssignScanProjectionInfo(ScanState *node)
{
Scan *scan = (Scan *) node->ps.plan;
ExecAssignScanProjectionInfoWithVarno(node, scan->scanrelid);
}
/* ----------------------------------------------------------------
* ExecInitIndexOnlyScan
*
* Initializes the index scan's state information, creates
* scan keys, and opens the base and index relations.
*
* Note: index scans have 2 sets of state information because
* we have to keep track of the base relation and the
* index relation.
* ----------------------------------------------------------------
*/
IndexOnlyScanState *
ExecInitIndexOnlyScan(IndexOnlyScan *node, EState *estate, int eflags)
{
IndexOnlyScanState *indexstate;
Relation currentRelation;
bool relistarget;
TupleDesc tupDesc;
/*
* create state structure
*/
indexstate = makeNode(IndexOnlyScanState);
indexstate->ss.ps.plan = (Plan *) node;
indexstate->ss.ps.state = estate;
indexstate->ioss_HeapFetches = 0;
/*
* Miscellaneous initialization
*
* create expression context for node
*/
ExecAssignExprContext(estate, &indexstate->ss.ps);
indexstate->ss.ps.ps_TupFromTlist = false;
/*
* initialize child expressions
*
* Note: we don't initialize all of the indexorderby expression, only the
* sub-parts corresponding to runtime keys (see below).
*/
indexstate->ss.ps.targetlist = (List *)
ExecInitExpr((Expr *) node->scan.plan.targetlist,
(PlanState *) indexstate);
indexstate->ss.ps.qual = (List *)
ExecInitExpr((Expr *) node->scan.plan.qual,
(PlanState *) indexstate);
indexstate->indexqual = (List *)
ExecInitExpr((Expr *) node->indexqual,
(PlanState *) indexstate);
/*
* tuple table initialization
*/
ExecInitResultTupleSlot(estate, &indexstate->ss.ps);
ExecInitScanTupleSlot(estate, &indexstate->ss);
/*
* open the base relation and acquire appropriate lock on it.
*/
currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
indexstate->ss.ss_currentRelation = currentRelation;
indexstate->ss.ss_currentScanDesc = NULL; /* no heap scan here */
/*
* Build the scan tuple type using the indextlist generated by the
* planner. We use this, rather than the index's physical tuple
* descriptor, because the latter contains storage column types not the
* types of the original datums. (It's the AM's responsibility to return
* suitable data anyway.)
*/
tupDesc = ExecTypeFromTL(node->indextlist, false);
ExecAssignScanType(&indexstate->ss, tupDesc);
/*
* Initialize result tuple type and projection info. The node's
* targetlist will contain Vars with varno = INDEX_VAR, referencing the
* scan tuple.
*/
ExecAssignResultTypeFromTL(&indexstate->ss.ps);
ExecAssignScanProjectionInfoWithVarno(&indexstate->ss, INDEX_VAR);
/*
* If we are just doing EXPLAIN (ie, aren't going to run the plan), stop
* here. This allows an index-advisor plugin to EXPLAIN a plan containing
* references to nonexistent indexes.
*/
if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
return indexstate;
/*
* Open the index relation.
*
* If the parent table is one of the target relations of the query, then
* InitPlan already opened and write-locked the index, so we can avoid
* taking another lock here. Otherwise we need a normal reader's lock.
*/
relistarget = ExecRelationIsTargetRelation(estate, node->scan.scanrelid);
indexstate->ioss_RelationDesc = index_open(node->indexid,
relistarget ? NoLock : AccessShareLock);
/*
* Initialize index-specific scan state
*/
indexstate->ioss_RuntimeKeysReady = false;
indexstate->ioss_RuntimeKeys = NULL;
indexstate->ioss_NumRuntimeKeys = 0;
/*
* build the index scan keys from the index qualification
*/
ExecIndexBuildScanKeys((PlanState *) indexstate,
indexstate->ioss_RelationDesc,
node->indexqual,
false,
&indexstate->ioss_ScanKeys,
&indexstate->ioss_NumScanKeys,
&indexstate->ioss_RuntimeKeys,
&indexstate->ioss_NumRuntimeKeys,
NULL, /* no ArrayKeys */
NULL);
/*
* any ORDER BY exprs have to be turned into scankeys in the same way
*/
ExecIndexBuildScanKeys((PlanState *) indexstate,
indexstate->ioss_RelationDesc,
node->indexorderby,
true,
&indexstate->ioss_OrderByKeys,
&indexstate->ioss_NumOrderByKeys,
&indexstate->ioss_RuntimeKeys,
&indexstate->ioss_NumRuntimeKeys,
NULL, /* no ArrayKeys */
NULL);
/*
* If we have runtime keys, we need an ExprContext to evaluate them. The
* node's standard context won't do because we want to reset that context
* for every tuple. So, build another context just like the other one...
* -tgl 7/11/00
*/
if (indexstate->ioss_NumRuntimeKeys != 0)
{
ExprContext *stdecontext = indexstate->ss.ps.ps_ExprContext;
ExecAssignExprContext(estate, &indexstate->ss.ps);
indexstate->ioss_RuntimeContext = indexstate->ss.ps.ps_ExprContext;
indexstate->ss.ps.ps_ExprContext = stdecontext;
}
else
{
indexstate->ioss_RuntimeContext = NULL;
}
/*
* Initialize scan descriptor.
*/
indexstate->ioss_ScanDesc = index_beginscan(currentRelation,
indexstate->ioss_RelationDesc,
estate->es_snapshot,
indexstate->ioss_NumScanKeys,
indexstate->ioss_NumOrderByKeys);
/* Set it up for index-only scan */
indexstate->ioss_ScanDesc->xs_want_itup = true;
indexstate->ioss_VMBuffer = InvalidBuffer;
/*
* If no run-time keys to calculate, go ahead and pass the scankeys to the
* index AM.
*/
if (indexstate->ioss_NumRuntimeKeys == 0)
index_rescan(indexstate->ioss_ScanDesc,
indexstate->ioss_ScanKeys,
indexstate->ioss_NumScanKeys,
indexstate->ioss_OrderByKeys,
indexstate->ioss_NumOrderByKeys);
/*
* all done.
*/
return indexstate;
}
CustomScanState *
ExecInitCustomScan(CustomScan *cscan, EState *estate, int eflags)
{
CustomScanState *css;
Relation scan_rel = NULL;
Index scanrelid = cscan->scan.scanrelid;
Index tlistvarno;
/*
* Allocate the CustomScanState object. We let the custom scan provider
* do the palloc, in case it wants to make a larger object that embeds
* CustomScanState as the first field. It must set the node tag and the
* methods field correctly at this time. Other standard fields should be
* set to zero.
*/
css = (CustomScanState *) cscan->methods->CreateCustomScanState(cscan);
Assert(IsA(css, CustomScanState));
/* ensure flags is filled correctly */
css->flags = cscan->flags;
/* fill up fields of ScanState */
css->ss.ps.plan = &cscan->scan.plan;
css->ss.ps.state = estate;
/* create expression context for node */
ExecAssignExprContext(estate, &css->ss.ps);
#ifdef PG95
css->ss.ps.ps_TupFromTlist = false;
#endif
/* initialize child expressions */
css->ss.ps.targetlist = (List *)
ExecInitExpr((Expr *) cscan->scan.plan.targetlist,
(PlanState *) css);
css->ss.ps.qual = (List *)
ExecInitExpr((Expr *) cscan->scan.plan.qual,
(PlanState *) css);
/* tuple table initialization */
#ifndef PG95
if (((Scan*)css->ss.ps.plan)->scanrelid) {
// For table scans
ExecInitScanTupleSlot(estate, &css->ss);
}
else {
// For tuple-table-slot scans (typically over Motion nodes)
css->ss.ss_ScanTupleSlot = ExecAllocTableSlot(&estate->es_tupleTable);
}
#else
ExecInitScanTupleSlot(estate, &css->ss);
#endif
ExecInitResultTupleSlot(estate, &css->ss.ps);
/*
* open the base relation, if any, and acquire an appropriate lock on it
*/
if (scanrelid > 0)
{
scan_rel = ExecOpenScanRelation(estate
, scanrelid
#ifdef PG95
, eflags
#endif
);
css->ss.ss_currentRelation = scan_rel;
}
/*
* Determine the scan tuple type. If the custom scan provider provided a
* targetlist describing the scan tuples, use that; else use base
* relation's rowtype.
*/
if (cscan->custom_scan_tlist != NIL || scan_rel == NULL)
{
// index-only scan? GP doesn't define INDEX_VAR
TupleDesc scan_tupdesc;
scan_tupdesc = ExecTypeFromTL(cscan->custom_scan_tlist, false);
ExecAssignScanType(&css->ss, scan_tupdesc);
#ifdef PG95
/* Node's targetlist will contain Vars with varno = INDEX_VAR */
tlistvarno = INDEX_VAR;
#endif
}
else
{
ExecAssignScanType(&css->ss, RelationGetDescr(scan_rel));
/* Node's targetlist will contain Vars with varno = scanrelid */
tlistvarno = scanrelid;
}
/*
* Initialize result tuple type and projection info.
*/
ExecAssignResultTypeFromTL(&css->ss.ps);
#ifdef PG95
ExecAssignScanProjectionInfoWithVarno(&css->ss, tlistvarno);
#else
ExecAssignScanProjectionInfo(&css->ss);
#endif
/*
* The callback of custom-scan provider applies the final initialization
* of the custom-scan-state node according to its logic.
*/
css->methods->BeginCustomScan(css, estate, eflags);
return css;
}
/* ----------------------------------------------------------------
* ExecInitForeignScan
* ----------------------------------------------------------------
*/
ForeignScanState *
ExecInitForeignScan(ForeignScan *node, EState *estate, int eflags)
{
ForeignScanState *scanstate;
Relation currentRelation = NULL;
Index scanrelid = node->scan.scanrelid;
Index tlistvarno;
FdwRoutine *fdwroutine;
/* check for unsupported flags */
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
/*
* create state structure
*/
scanstate = makeNode(ForeignScanState);
scanstate->ss.ps.plan = (Plan *) node;
scanstate->ss.ps.state = estate;
/*
* Miscellaneous initialization
*
* create expression context for node
*/
ExecAssignExprContext(estate, &scanstate->ss.ps);
scanstate->ss.ps.ps_TupFromTlist = false;
/*
* initialize child expressions
*/
scanstate->ss.ps.targetlist = (List *)
ExecInitExpr((Expr *) node->scan.plan.targetlist,
(PlanState *) scanstate);
scanstate->ss.ps.qual = (List *)
ExecInitExpr((Expr *) node->scan.plan.qual,
(PlanState *) scanstate);
scanstate->fdw_recheck_quals = (List *)
ExecInitExpr((Expr *) node->fdw_recheck_quals,
(PlanState *) scanstate);
/*
* tuple table initialization
*/
ExecInitResultTupleSlot(estate, &scanstate->ss.ps);
ExecInitScanTupleSlot(estate, &scanstate->ss);
/*
* open the base relation, if any, and acquire an appropriate lock on it;
* also acquire function pointers from the FDW's handler
*/
if (scanrelid > 0)
{
currentRelation = ExecOpenScanRelation(estate, scanrelid, eflags);
scanstate->ss.ss_currentRelation = currentRelation;
fdwroutine = GetFdwRoutineForRelation(currentRelation, true);
}
else
{
/* We can't use the relcache, so get fdwroutine the hard way */
fdwroutine = GetFdwRoutineByServerId(node->fs_server);
}
/*
* Determine the scan tuple type. If the FDW provided a targetlist
* describing the scan tuples, use that; else use base relation's rowtype.
*/
if (node->fdw_scan_tlist != NIL || currentRelation == NULL)
{
TupleDesc scan_tupdesc;
scan_tupdesc = ExecTypeFromTL(node->fdw_scan_tlist, false);
ExecAssignScanType(&scanstate->ss, scan_tupdesc);
/* Node's targetlist will contain Vars with varno = INDEX_VAR */
tlistvarno = INDEX_VAR;
}
else
{
ExecAssignScanType(&scanstate->ss, RelationGetDescr(currentRelation));
/* Node's targetlist will contain Vars with varno = scanrelid */
tlistvarno = scanrelid;
}
/*
* Initialize result tuple type and projection info.
*/
ExecAssignResultTypeFromTL(&scanstate->ss.ps);
ExecAssignScanProjectionInfoWithVarno(&scanstate->ss, tlistvarno);
/*
* Initialize FDW-related state.
*/
scanstate->fdwroutine = fdwroutine;
scanstate->fdw_state = NULL;
/* Initialize any outer plan. */
if (outerPlan(node))
outerPlanState(scanstate) =
ExecInitNode(outerPlan(node), estate, eflags);
/*
* Tell the FDW to initialize the scan.
*/
fdwroutine->BeginForeignScan(scanstate, eflags);
return scanstate;
}
