Select Git revision
nodeFunctionscan.c
-
Bruce Momjian authored
Backpatch certain files through 9.0
Bruce Momjian authoredBackpatch certain files through 9.0
nodeFunctionscan.c 16.59 KiB
/*-------------------------------------------------------------------------
*
* nodeFunctionscan.c
* Support routines for scanning RangeFunctions (functions in rangetable).
*
* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/executor/nodeFunctionscan.c
*
*-------------------------------------------------------------------------
*/
/*
* 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.
* ExecReScanFunctionScan rescans the function
*/
#include "postgres.h"
#include "catalog/pg_type.h"
#include "executor/nodeFunctionscan.h"
#include "funcapi.h"
#include "nodes/nodeFuncs.h"
#include "utils/builtins.h"
#include "utils/memutils.h"
/*
* Runtime data for each function being scanned.
*/
typedef struct FunctionScanPerFuncState
{
ExprState *funcexpr; /* state of the expression being evaluated */
TupleDesc tupdesc; /* desc of the function result type */
int colcount; /* expected number of result columns */
Tuplestorestate *tstore; /* holds the function result set */
int64 rowcount; /* # of rows in result set, -1 if not known */
TupleTableSlot *func_slot; /* function result slot (or NULL) */
} FunctionScanPerFuncState;
static TupleTableSlot *FunctionNext(FunctionScanState *node);
/* ----------------------------------------------------------------
* Scan Support
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* FunctionNext
*
* This is a workhorse for ExecFunctionScan
* ----------------------------------------------------------------
*/
static TupleTableSlot *
FunctionNext(FunctionScanState *node)
{
EState *estate;
ScanDirection direction;
TupleTableSlot *scanslot;
bool alldone;
int64 oldpos;
int funcno;
int att;
/* * get information from the estate and scan state
*/
estate = node->ss.ps.state;
direction = estate->es_direction;
scanslot = node->ss.ss_ScanTupleSlot;
if (node->simple)
{
/*
* Fast path for the trivial case: the function return type and scan
* result type are the same, so we fetch the function result straight
* into the scan result slot. No need to update ordinality or
* rowcounts either.
*/
Tuplestorestate *tstore = node->funcstates[0].tstore;
/*
* If first time through, read all tuples from function and put them
* in a tuplestore. Subsequent calls just fetch tuples from
* tuplestore.
*/
if (tstore == NULL)
{
node->funcstates[0].tstore = tstore =
ExecMakeTableFunctionResult(node->funcstates[0].funcexpr,
node->ss.ps.ps_ExprContext,
node->argcontext,
node->funcstates[0].tupdesc,
node->eflags & EXEC_FLAG_BACKWARD);
/*
* paranoia - cope if the function, which may have constructed the
* tuplestore itself, didn't leave it pointing at the start. This
* call is fast, so the overhead shouldn't be an issue.
*/
tuplestore_rescan(tstore);
}
/*
* Get the next tuple from tuplestore.
*/
(void) tuplestore_gettupleslot(tstore,
ScanDirectionIsForward(direction),
false,
scanslot);
return scanslot;
}
/*
* Increment or decrement ordinal counter before checking for end-of-data,
* so that we can move off either end of the result by 1 (and no more than
* 1) without losing correct count. See PortalRunSelect for why we can
* assume that we won't be called repeatedly in the end-of-data state.
*/
oldpos = node->ordinal;
if (ScanDirectionIsForward(direction))
node->ordinal++;
else
node->ordinal--;
/*
* Main loop over functions.
*
* We fetch the function results into func_slots (which match the function
* return types), and then copy the values to scanslot (which matches the
* scan result type), setting the ordinal column (if any) as well.
*/
ExecClearTuple(scanslot);
att = 0;
alldone = true; for (funcno = 0; funcno < node->nfuncs; funcno++)
{
FunctionScanPerFuncState *fs = &node->funcstates[funcno];
int i;
/*
* If first time through, read all tuples from function and put them
* in a tuplestore. Subsequent calls just fetch tuples from
* tuplestore.
*/
if (fs->tstore == NULL)
{
fs->tstore =
ExecMakeTableFunctionResult(fs->funcexpr,
node->ss.ps.ps_ExprContext,
node->argcontext,
fs->tupdesc,
node->eflags & EXEC_FLAG_BACKWARD);
/*
* paranoia - cope if the function, which may have constructed the
* tuplestore itself, didn't leave it pointing at the start. This
* call is fast, so the overhead shouldn't be an issue.
*/
tuplestore_rescan(fs->tstore);
}
/*
* Get the next tuple from tuplestore.
*
* If we have a rowcount for the function, and we know the previous
* read position was out of bounds, don't try the read. This allows
* backward scan to work when there are mixed row counts present.
*/
if (fs->rowcount != -1 && fs->rowcount < oldpos)
ExecClearTuple(fs->func_slot);
else
(void) tuplestore_gettupleslot(fs->tstore,
ScanDirectionIsForward(direction),
false,
fs->func_slot);
if (TupIsNull(fs->func_slot))
{
/*
* If we ran out of data for this function in the forward
* direction then we now know how many rows it returned. We need
* to know this in order to handle backwards scans. The row count
* we store is actually 1+ the actual number, because we have to
* position the tuplestore 1 off its end sometimes.
*/
if (ScanDirectionIsForward(direction) && fs->rowcount == -1)
fs->rowcount = node->ordinal;
/*
* populate the result cols with nulls
*/
for (i = 0; i < fs->colcount; i++)
{
scanslot->tts_values[att] = (Datum) 0;
scanslot->tts_isnull[att] = true;
att++;
}
}
else
{
/*
* we have a result, so just copy it to the result cols.
*/
slot_getallattrs(fs->func_slot);
for (i = 0; i < fs->colcount; i++)
{
scanslot->tts_values[att] = fs->func_slot->tts_values[i];
scanslot->tts_isnull[att] = fs->func_slot->tts_isnull[i];
att++;
}
/*
* We're not done until every function result is exhausted; we pad
* the shorter results with nulls until then.
*/
alldone = false;
}
}
/*
* ordinal col is always last, per spec.
*/
if (node->ordinality)
{
scanslot->tts_values[att] = Int64GetDatumFast(node->ordinal);
scanslot->tts_isnull[att] = false;
}
/*
* If alldone, we just return the previously-cleared scanslot. Otherwise,
* finish creating the virtual tuple.
*/
if (!alldone)
ExecStoreVirtualTuple(scanslot);
return scanslot;
}
/*
* FunctionRecheck -- access method routine to recheck a tuple in EvalPlanQual
*/
static bool
FunctionRecheck(FunctionScanState *node, TupleTableSlot *slot)
{
/* nothing to check */
return true;
}
/* ----------------------------------------------------------------
* ExecFunctionScan(node)
*
* Scans the function sequentially and returns the next qualifying
* tuple.
* We call the ExecScan() routine and pass it the appropriate
* access method functions.
* ----------------------------------------------------------------
*/
TupleTableSlot *
ExecFunctionScan(FunctionScanState *node)
{
return ExecScan(&node->ss,
(ExecScanAccessMtd) FunctionNext,
(ExecScanRecheckMtd) FunctionRecheck);
}
/* ----------------------------------------------------------------
* ExecInitFunctionScan
* ----------------------------------------------------------------
*/
FunctionScanState *
ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags)
{
FunctionScanState *scanstate; int nfuncs = list_length(node->functions);
TupleDesc scan_tupdesc;
int i,
natts;
ListCell *lc;
/* check for unsupported flags */
Assert(!(eflags & EXEC_FLAG_MARK));
/*
* 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;
scanstate->eflags = eflags;
/*
* are we adding an ordinality column?
*/
scanstate->ordinality = node->funcordinality;
scanstate->nfuncs = nfuncs;
if (nfuncs == 1 && !node->funcordinality)
scanstate->simple = true;
else
scanstate->simple = false;
/*
* Ordinal 0 represents the "before the first row" position.
*
* We need to track ordinal position even when not adding an ordinality
* column to the result, in order to handle backwards scanning properly
* with multiple functions with different result sizes. (We can't position
* any individual function's tuplestore any more than 1 place beyond its
* end, so when scanning backwards, we need to know when to start
* including the function in the scan again.)
*/
scanstate->ordinal = 0;
/*
* Miscellaneous initialization
*
* create expression context for node
*/
ExecAssignExprContext(estate, &scanstate->ss.ps);
scanstate->ss.ps.ps_TupFromTlist = false;
/*
* 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);
scanstate->funcstates = palloc(nfuncs * sizeof(FunctionScanPerFuncState));
natts = 0;
i = 0;
foreach(lc, node->functions)
{
RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
Node *funcexpr = rtfunc->funcexpr;
int colcount = rtfunc->funccolcount;
FunctionScanPerFuncState *fs = &scanstate->funcstates[i];
TypeFuncClass functypclass;
Oid funcrettype;
TupleDesc tupdesc;
fs->funcexpr = ExecInitExpr((Expr *) funcexpr, (PlanState *) scanstate);
/*
* Don't allocate the tuplestores; the actual calls to the functions
* do that. NULL means that we have not called the function yet (or
* need to call it again after a rescan).
*/
fs->tstore = NULL;
fs->rowcount = -1;
/*
* Now determine if the function returns a simple or composite type,
* and build an appropriate tupdesc. Note that in the composite case,
* the function may now return more columns than it did when the plan
* was made; we have to ignore any columns beyond "colcount".
*/
functypclass = get_expr_result_type(funcexpr,
&funcrettype,
&tupdesc);
if (functypclass == TYPEFUNC_COMPOSITE)
{
/* Composite data type, e.g. a table's row type */
Assert(tupdesc);
Assert(tupdesc->natts >= colcount);
/* Must copy it out of typcache for safety */
tupdesc = CreateTupleDescCopy(tupdesc);
}
else if (functypclass == TYPEFUNC_SCALAR)
{
/* Base data type, i.e. scalar */
tupdesc = CreateTemplateTupleDesc(1, false);
TupleDescInitEntry(tupdesc,
(AttrNumber) 1,
NULL, /* don't care about the name here */
funcrettype,
-1,
0);
TupleDescInitEntryCollation(tupdesc,
(AttrNumber) 1,
exprCollation(funcexpr));
}
else if (functypclass == TYPEFUNC_RECORD)
{
tupdesc = BuildDescFromLists(rtfunc->funccolnames,
rtfunc->funccoltypes,
rtfunc->funccoltypmods,
rtfunc->funccolcollations);
/*
* For RECORD results, make sure a typmod has been assigned. (The
* function should do this for itself, but let's cover things in
* case it doesn't.)
*/
BlessTupleDesc(tupdesc); }
else
{
/* crummy error message, but parser should have caught this */
elog(ERROR, "function in FROM has unsupported return type");
}
fs->tupdesc = tupdesc;
fs->colcount = colcount;
/*
* We only need separate slots for the function results if we are
* doing ordinality or multiple functions; otherwise, we'll fetch
* function results directly into the scan slot.
*/
if (!scanstate->simple)
{
fs->func_slot = ExecInitExtraTupleSlot(estate);
ExecSetSlotDescriptor(fs->func_slot, fs->tupdesc);
}
else
fs->func_slot = NULL;
natts += colcount;
i++;
}
/*
* Create the combined TupleDesc
*
* If there is just one function without ordinality, the scan result
* tupdesc is the same as the function result tupdesc --- except that we
* may stuff new names into it below, so drop any rowtype label.
*/
if (scanstate->simple)
{
scan_tupdesc = CreateTupleDescCopy(scanstate->funcstates[0].tupdesc);
scan_tupdesc->tdtypeid = RECORDOID;
scan_tupdesc->tdtypmod = -1;
}
else
{
AttrNumber attno = 0;
if (node->funcordinality)
natts++;
scan_tupdesc = CreateTemplateTupleDesc(natts, false);
for (i = 0; i < nfuncs; i++)
{
TupleDesc tupdesc = scanstate->funcstates[i].tupdesc;
int colcount = scanstate->funcstates[i].colcount;
int j;
for (j = 1; j <= colcount; j++)
TupleDescCopyEntry(scan_tupdesc, ++attno, tupdesc, j);
}
/* If doing ordinality, add a column of type "bigint" at the end */
if (node->funcordinality)
{
TupleDescInitEntry(scan_tupdesc,
++attno,
NULL, /* don't care about the name here */
INT8OID,
-1,
0);
}
Assert(attno == natts);
}
ExecAssignScanType(&scanstate->ss, scan_tupdesc);
/*
* Initialize result tuple type and projection info.
*/
ExecAssignResultTypeFromTL(&scanstate->ss.ps);
ExecAssignScanProjectionInfo(&scanstate->ss);
/*
* Create a memory context that ExecMakeTableFunctionResult can use to
* evaluate function arguments in. We can't use the per-tuple context for
* this because it gets reset too often; but we don't want to leak
* evaluation results into the query-lifespan context either. We just
* need one context, because we evaluate each function separately.
*/
scanstate->argcontext = AllocSetContextCreate(CurrentMemoryContext,
"Table function arguments",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
return scanstate;
}
/* ----------------------------------------------------------------
* ExecEndFunctionScan
*
* frees any storage allocated through C routines.
* ----------------------------------------------------------------
*/
void
ExecEndFunctionScan(FunctionScanState *node)
{
int i;
/*
* Free the exprcontext
*/
ExecFreeExprContext(&node->ss.ps);
/*
* clean out the tuple table
*/
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
ExecClearTuple(node->ss.ss_ScanTupleSlot);
/*
* Release slots and tuplestore resources
*/
for (i = 0; i < node->nfuncs; i++)
{
FunctionScanPerFuncState *fs = &node->funcstates[i];
if (fs->func_slot)
ExecClearTuple(fs->func_slot);
if (fs->tstore != NULL)
{
tuplestore_end(node->funcstates[i].tstore);
fs->tstore = NULL;
}
}
}
/* ----------------------------------------------------------------
* ExecReScanFunctionScan
* * Rescans the relation.
* ----------------------------------------------------------------
*/
void
ExecReScanFunctionScan(FunctionScanState *node)
{
FunctionScan *scan = (FunctionScan *) node->ss.ps.plan;
int i;
Bitmapset *chgparam = node->ss.ps.chgParam;
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
for (i = 0; i < node->nfuncs; i++)
{
FunctionScanPerFuncState *fs = &node->funcstates[i];
if (fs->func_slot)
ExecClearTuple(fs->func_slot);
}
ExecScanReScan(&node->ss);
/*
* Here we have a choice whether to drop the tuplestores (and recompute
* the function outputs) or just rescan them. We must recompute if an
* expression contains changed parameters, else we rescan.
*
* XXX maybe we should recompute if the function is volatile? But in
* general the executor doesn't conditionalize its actions on that.
*/
if (chgparam)
{
ListCell *lc;
i = 0;
foreach(lc, scan->functions)
{
RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
if (bms_overlap(chgparam, rtfunc->funcparams))
{
if (node->funcstates[i].tstore != NULL)
{
tuplestore_end(node->funcstates[i].tstore);
node->funcstates[i].tstore = NULL;
}
node->funcstates[i].rowcount = -1;
}
i++;
}
}
/* Reset ordinality counter */
node->ordinal = 0;
/* Make sure we rewind any remaining tuplestores */
for (i = 0; i < node->nfuncs; i++)
{
if (node->funcstates[i].tstore != NULL)
tuplestore_rescan(node->funcstates[i].tstore);
}
}