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nodeFunctionscan.c
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PostgreSQL Daemon authored
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PostgreSQL Daemon authored$Header: -> $PostgreSQL Changes ...
nodeFunctionscan.c 10.10 KiB
/*-------------------------------------------------------------------------
*
* nodeFunctionscan.c
* Support routines for scanning RangeFunctions (functions in rangetable).
*
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeFunctionscan.c,v 1.23 2003/11/29 19:51:48 pgsql Exp $
*
*-------------------------------------------------------------------------
*/
/*
* INTERFACE ROUTINES
* ExecFunctionScan scans a function.
* ExecFunctionNext retrieve next tuple in sequential order.
* ExecInitFunctionScan creates and initializes a functionscan node.
* ExecEndFunctionScan releases any storage allocated.
* ExecFunctionReScan rescans the function
*/
#include "postgres.h"
#include "access/heapam.h"
#include "catalog/pg_type.h"
#include "executor/execdebug.h"
#include "executor/execdefs.h"
#include "executor/execdesc.h"
#include "executor/nodeFunctionscan.h"
#include "parser/parsetree.h"
#include "parser/parse_expr.h"
#include "parser/parse_type.h"
#include "utils/lsyscache.h"
static TupleTableSlot *FunctionNext(FunctionScanState *node);
static bool tupledesc_match(TupleDesc dst_tupdesc, TupleDesc src_tupdesc);
/* ----------------------------------------------------------------
* Scan Support
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* FunctionNext
*
* This is a workhorse for ExecFunctionScan
* ----------------------------------------------------------------
*/
static TupleTableSlot *
FunctionNext(FunctionScanState *node)
{
TupleTableSlot *slot;
EState *estate;
ScanDirection direction;
Tuplestorestate *tuplestorestate;
bool should_free;
HeapTuple heapTuple;
/*
* get information from the estate and scan state
*/
estate = node->ss.ps.state;
direction = estate->es_direction;
tuplestorestate = node->tuplestorestate;
/*
* If first time through, read all tuples from function and put them
* in a tuplestore. Subsequent calls just fetch tuples from * tuplestore.
*/
if (tuplestorestate == NULL)
{
ExprContext *econtext = node->ss.ps.ps_ExprContext;
TupleDesc funcTupdesc;
node->tuplestorestate = tuplestorestate =
ExecMakeTableFunctionResult(node->funcexpr,
econtext,
node->tupdesc,
&funcTupdesc);
/*
* If function provided a tupdesc, cross-check it. We only really
* need to do this for functions returning RECORD, but might as
* well do it always.
*/
if (funcTupdesc && !tupledesc_match(node->tupdesc, funcTupdesc))
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("query-specified return row and actual function return row do not match")));
}
/*
* Get the next tuple from tuplestore. Return NULL if no more tuples.
*/
slot = node->ss.ss_ScanTupleSlot;
if (tuplestorestate)
heapTuple = tuplestore_getheaptuple(tuplestorestate,
ScanDirectionIsForward(direction),
&should_free);
else
{
heapTuple = NULL;
should_free = false;
}
return ExecStoreTuple(heapTuple, slot, InvalidBuffer, should_free);
}
/* ----------------------------------------------------------------
* ExecFunctionScan(node)
*
* Scans the function sequentially and returns the next qualifying
* tuple.
* It calls the ExecScan() routine and passes it the access method
* which retrieves tuples sequentially.
*
*/
TupleTableSlot *
ExecFunctionScan(FunctionScanState *node)
{
/*
* use FunctionNext as access method
*/
return ExecScan(&node->ss, (ExecScanAccessMtd) FunctionNext);
}
/* ----------------------------------------------------------------
* ExecInitFunctionScan
* ----------------------------------------------------------------
*/
FunctionScanState *
ExecInitFunctionScan(FunctionScan *node, EState *estate)
{
FunctionScanState *scanstate;
RangeTblEntry *rte;
Oid funcrettype; char functyptype;
TupleDesc tupdesc = NULL;
/*
* FunctionScan should not have any children.
*/
Assert(outerPlan(node) == NULL);
Assert(innerPlan(node) == NULL);
/*
* create new ScanState for node
*/
scanstate = makeNode(FunctionScanState);
scanstate->ss.ps.plan = (Plan *) node;
scanstate->ss.ps.state = estate;
/*
* Miscellaneous initialization
*
* create expression context for node
*/
ExecAssignExprContext(estate, &scanstate->ss.ps);
#define FUNCTIONSCAN_NSLOTS 2
/*
* tuple table initialization
*/
ExecInitResultTupleSlot(estate, &scanstate->ss.ps);
ExecInitScanTupleSlot(estate, &scanstate->ss);
/*
* 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);
/*
* get info about function
*/
rte = rt_fetch(node->scan.scanrelid, estate->es_range_table);
Assert(rte->rtekind == RTE_FUNCTION);
funcrettype = exprType(rte->funcexpr);
/*
* Now determine if the function returns a simple or composite type,
* and build an appropriate tupdesc.
*/
functyptype = get_typtype(funcrettype);
if (functyptype == 'c')
{
/*
* Composite data type, i.e. a table's row type
*/
Oid funcrelid;
Relation rel;
funcrelid = typeidTypeRelid(funcrettype);
if (!OidIsValid(funcrelid))
elog(ERROR, "invalid typrelid for complex type %u",
funcrettype);
rel = relation_open(funcrelid, AccessShareLock);
tupdesc = CreateTupleDescCopy(RelationGetDescr(rel));
relation_close(rel, AccessShareLock);
} else if (functyptype == 'b' || functyptype == 'd')
{
/*
* Must be a base data type, i.e. scalar
*/
char *attname = strVal(lfirst(rte->eref->colnames));
tupdesc = CreateTemplateTupleDesc(1, false);
TupleDescInitEntry(tupdesc,
(AttrNumber) 1,
attname,
funcrettype,
-1,
0,
false);
}
else if (functyptype == 'p' && funcrettype == RECORDOID)
{
/*
* Must be a pseudo type, i.e. record
*/
tupdesc = BuildDescForRelation(rte->coldeflist);
}
else
{
/* crummy error message, but parser should have caught this */
elog(ERROR, "function in FROM has unsupported return type");
}
scanstate->tupdesc = tupdesc;
ExecSetSlotDescriptor(scanstate->ss.ss_ScanTupleSlot,
tupdesc, false);
/*
* Other node-specific setup
*/
scanstate->tuplestorestate = NULL;
scanstate->funcexpr = ExecInitExpr((Expr *) rte->funcexpr,
(PlanState *) scanstate);
scanstate->ss.ps.ps_TupFromTlist = false;
/*
* Initialize result tuple type and projection info.
*/
ExecAssignResultTypeFromTL(&scanstate->ss.ps);
ExecAssignProjectionInfo(&scanstate->ss.ps);
return scanstate;
}
int
ExecCountSlotsFunctionScan(FunctionScan *node)
{
return ExecCountSlotsNode(outerPlan(node)) +
ExecCountSlotsNode(innerPlan(node)) +
FUNCTIONSCAN_NSLOTS;
}
/* ----------------------------------------------------------------
* ExecEndFunctionScan
*
* frees any storage allocated through C routines.
* ----------------------------------------------------------------
*/
void
ExecEndFunctionScan(FunctionScanState *node)
{
/*
* Free the exprcontext */
ExecFreeExprContext(&node->ss.ps);
/*
* clean out the tuple table
*/
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
ExecClearTuple(node->ss.ss_ScanTupleSlot);
/*
* Release tuplestore resources
*/
if (node->tuplestorestate != NULL)
tuplestore_end(node->tuplestorestate);
node->tuplestorestate = NULL;
}
/* ----------------------------------------------------------------
* ExecFunctionMarkPos
*
* Calls tuplestore to save the current position in the stored file.
* ----------------------------------------------------------------
*/
void
ExecFunctionMarkPos(FunctionScanState *node)
{
/*
* if we haven't materialized yet, just return.
*/
if (!node->tuplestorestate)
return;
tuplestore_markpos(node->tuplestorestate);
}
/* ----------------------------------------------------------------
* ExecFunctionRestrPos
*
* Calls tuplestore to restore the last saved file position.
* ----------------------------------------------------------------
*/
void
ExecFunctionRestrPos(FunctionScanState *node)
{
/*
* if we haven't materialized yet, just return.
*/
if (!node->tuplestorestate)
return;
tuplestore_restorepos(node->tuplestorestate);
}
/* ----------------------------------------------------------------
* ExecFunctionReScan
*
* Rescans the relation.
* ----------------------------------------------------------------
*/
void
ExecFunctionReScan(FunctionScanState *node, ExprContext *exprCtxt)
{
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
/*
* If we haven't materialized yet, just return.
*/
if (!node->tuplestorestate)
return;
/*
* Here we have a choice whether to drop the tuplestore (and recompute
* the function outputs) or just rescan it. This should depend on
* whether the function expression contains parameters and/or is
* marked volatile. FIXME soon.
*/
if (node->ss.ps.chgParam != NULL)
{
tuplestore_end(node->tuplestorestate);
node->tuplestorestate = NULL;
}
else
tuplestore_rescan(node->tuplestorestate);
}
/*
* Check that function result tuple type (src_tupdesc) matches or can be
* considered to match what the query expects (dst_tupdesc).
*
* We really only care about number of attributes and data type.
* Also, we can ignore type mismatch on columns that are dropped in the
* destination type, so long as the physical storage matches. This is
* helpful in some cases involving out-of-date cached plans.
*/
static bool
tupledesc_match(TupleDesc dst_tupdesc, TupleDesc src_tupdesc)
{
int i;
if (dst_tupdesc->natts != src_tupdesc->natts)
return false;
for (i = 0; i < dst_tupdesc->natts; i++)
{
Form_pg_attribute dattr = dst_tupdesc->attrs[i];
Form_pg_attribute sattr = src_tupdesc->attrs[i];
if (dattr->atttypid == sattr->atttypid)
continue; /* no worries */
if (!dattr->attisdropped)
return false;
if (dattr->attlen != sattr->attlen ||
dattr->attalign != sattr->attalign)
return false;
}
return true;
}