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Diffstat (limited to 'src/backend/executor/nodeFunctionscan.c')
| -rw-r--r-- | src/backend/executor/nodeFunctionscan.c | 620 |
1 files changed, 620 insertions, 0 deletions
diff --git a/src/backend/executor/nodeFunctionscan.c b/src/backend/executor/nodeFunctionscan.c new file mode 100644 index 0000000..b31b2b2 --- /dev/null +++ b/src/backend/executor/nodeFunctionscan.c @@ -0,0 +1,620 @@ +/*------------------------------------------------------------------------- + * + * nodeFunctionscan.c + * Support routines for scanning RangeFunctions (functions in rangetable). + * + * Portions Copyright (c) 1996-2021, 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 +{ + SetExprState *setexpr; /* 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].setexpr, + 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->setexpr, + 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. + * ---------------------------------------------------------------- + */ +static TupleTableSlot * +ExecFunctionScan(PlanState *pstate) +{ + FunctionScanState *node = castNode(FunctionScanState, pstate); + + 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->ss.ps.ExecProcNode = ExecFunctionScan; + 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->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->setexpr = + ExecInitTableFunctionResult((Expr *) funcexpr, + scanstate->ss.ps.ps_ExprContext, + &scanstate->ss.ps); + + /* + * 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 || + functypclass == TYPEFUNC_COMPOSITE_DOMAIN) + { + /* 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); + 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, fs->tupdesc, + &TTSOpsMinimalTuple); + } + 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); + + 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); + } + + /* + * Initialize scan slot and type. + */ + ExecInitScanTupleSlot(estate, &scanstate->ss, scan_tupdesc, + &TTSOpsMinimalTuple); + + /* + * Initialize result slot, type and projection. + */ + ExecInitResultTypeTL(&scanstate->ss.ps); + ExecAssignScanProjectionInfo(&scanstate->ss); + + /* + * initialize child expressions + */ + scanstate->ss.ps.qual = + ExecInitQual(node->scan.plan.qual, (PlanState *) scanstate); + + /* + * 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_SIZES); + + 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 + */ + if (node->ss.ps.ps_ResultTupleSlot) + 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; + + if (node->ss.ps.ps_ResultTupleSlot) + 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); + } +} |