/*------------------------------------------------------------------------- * * 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); } }