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Diffstat (limited to 'src/backend/executor/execSRF.c')
| -rw-r--r-- | src/backend/executor/execSRF.c | 980 |
1 files changed, 980 insertions, 0 deletions
diff --git a/src/backend/executor/execSRF.c b/src/backend/executor/execSRF.c new file mode 100644 index 0000000..545b6c1 --- /dev/null +++ b/src/backend/executor/execSRF.c @@ -0,0 +1,980 @@ +/*------------------------------------------------------------------------- + * + * execSRF.c + * Routines implementing the API for set-returning functions + * + * This file serves nodeFunctionscan.c and nodeProjectSet.c, providing + * common code for calling set-returning functions according to the + * ReturnSetInfo API. + * + * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * + * IDENTIFICATION + * src/backend/executor/execSRF.c + * + *------------------------------------------------------------------------- + */ +#include "postgres.h" + +#include "access/htup_details.h" +#include "catalog/objectaccess.h" +#include "executor/execdebug.h" +#include "funcapi.h" +#include "miscadmin.h" +#include "nodes/nodeFuncs.h" +#include "parser/parse_coerce.h" +#include "pgstat.h" +#include "utils/acl.h" +#include "utils/builtins.h" +#include "utils/lsyscache.h" +#include "utils/memutils.h" +#include "utils/typcache.h" + + +/* static function decls */ +static void init_sexpr(Oid foid, Oid input_collation, Expr *node, + SetExprState *sexpr, PlanState *parent, + MemoryContext sexprCxt, bool allowSRF, bool needDescForSRF); +static void ShutdownSetExpr(Datum arg); +static void ExecEvalFuncArgs(FunctionCallInfo fcinfo, + List *argList, ExprContext *econtext); +static void ExecPrepareTuplestoreResult(SetExprState *sexpr, + ExprContext *econtext, + Tuplestorestate *resultStore, + TupleDesc resultDesc); +static void tupledesc_match(TupleDesc dst_tupdesc, TupleDesc src_tupdesc); + + +/* + * Prepare function call in FROM (ROWS FROM) for execution. + * + * This is used by nodeFunctionscan.c. + */ +SetExprState * +ExecInitTableFunctionResult(Expr *expr, + ExprContext *econtext, PlanState *parent) +{ + SetExprState *state = makeNode(SetExprState); + + state->funcReturnsSet = false; + state->expr = expr; + state->func.fn_oid = InvalidOid; + + /* + * Normally the passed expression tree will be a FuncExpr, since the + * grammar only allows a function call at the top level of a table + * function reference. However, if the function doesn't return set then + * the planner might have replaced the function call via constant-folding + * or inlining. So if we see any other kind of expression node, execute + * it via the general ExecEvalExpr() code. That code path will not + * support set-returning functions buried in the expression, though. + */ + if (IsA(expr, FuncExpr)) + { + FuncExpr *func = (FuncExpr *) expr; + + state->funcReturnsSet = func->funcretset; + state->args = ExecInitExprList(func->args, parent); + + init_sexpr(func->funcid, func->inputcollid, expr, state, parent, + econtext->ecxt_per_query_memory, func->funcretset, false); + } + else + { + state->elidedFuncState = ExecInitExpr(expr, parent); + } + + return state; +} + +/* + * ExecMakeTableFunctionResult + * + * Evaluate a table function, producing a materialized result in a Tuplestore + * object. + * + * This is used by nodeFunctionscan.c. + */ +Tuplestorestate * +ExecMakeTableFunctionResult(SetExprState *setexpr, + ExprContext *econtext, + MemoryContext argContext, + TupleDesc expectedDesc, + bool randomAccess) +{ + Tuplestorestate *tupstore = NULL; + TupleDesc tupdesc = NULL; + Oid funcrettype; + bool returnsTuple; + bool returnsSet = false; + FunctionCallInfo fcinfo; + PgStat_FunctionCallUsage fcusage; + ReturnSetInfo rsinfo; + HeapTupleData tmptup; + MemoryContext callerContext; + bool first_time = true; + + /* + * Execute per-tablefunc actions in appropriate context. + * + * The FunctionCallInfo needs to live across all the calls to a + * ValuePerCall function, so it can't be allocated in the per-tuple + * context. Similarly, the function arguments need to be evaluated in a + * context that is longer lived than the per-tuple context: The argument + * values would otherwise disappear when we reset that context in the + * inner loop. As the caller's CurrentMemoryContext is typically a + * query-lifespan context, we don't want to leak memory there. We require + * the caller to pass a separate memory context that can be used for this, + * and can be reset each time through to avoid bloat. + */ + MemoryContextReset(argContext); + callerContext = MemoryContextSwitchTo(argContext); + + funcrettype = exprType((Node *) setexpr->expr); + + returnsTuple = type_is_rowtype(funcrettype); + + /* + * Prepare a resultinfo node for communication. We always do this even if + * not expecting a set result, so that we can pass expectedDesc. In the + * generic-expression case, the expression doesn't actually get to see the + * resultinfo, but set it up anyway because we use some of the fields as + * our own state variables. + */ + rsinfo.type = T_ReturnSetInfo; + rsinfo.econtext = econtext; + rsinfo.expectedDesc = expectedDesc; + rsinfo.allowedModes = (int) (SFRM_ValuePerCall | SFRM_Materialize | SFRM_Materialize_Preferred); + if (randomAccess) + rsinfo.allowedModes |= (int) SFRM_Materialize_Random; + rsinfo.returnMode = SFRM_ValuePerCall; + /* isDone is filled below */ + rsinfo.setResult = NULL; + rsinfo.setDesc = NULL; + + fcinfo = palloc(SizeForFunctionCallInfo(list_length(setexpr->args))); + + /* + * Normally the passed expression tree will be a SetExprState, since the + * grammar only allows a function call at the top level of a table + * function reference. However, if the function doesn't return set then + * the planner might have replaced the function call via constant-folding + * or inlining. So if we see any other kind of expression node, execute + * it via the general ExecEvalExpr() code; the only difference is that we + * don't get a chance to pass a special ReturnSetInfo to any functions + * buried in the expression. + */ + if (!setexpr->elidedFuncState) + { + /* + * This path is similar to ExecMakeFunctionResultSet. + */ + returnsSet = setexpr->funcReturnsSet; + InitFunctionCallInfoData(*fcinfo, &(setexpr->func), + list_length(setexpr->args), + setexpr->fcinfo->fncollation, + NULL, (Node *) &rsinfo); + /* evaluate the function's argument list */ + Assert(CurrentMemoryContext == argContext); + ExecEvalFuncArgs(fcinfo, setexpr->args, econtext); + + /* + * If function is strict, and there are any NULL arguments, skip + * calling the function and act like it returned NULL (or an empty + * set, in the returns-set case). + */ + if (setexpr->func.fn_strict) + { + int i; + + for (i = 0; i < fcinfo->nargs; i++) + { + if (fcinfo->args[i].isnull) + goto no_function_result; + } + } + } + else + { + /* Treat setexpr as a generic expression */ + InitFunctionCallInfoData(*fcinfo, NULL, 0, InvalidOid, NULL, NULL); + } + + /* + * Switch to short-lived context for calling the function or expression. + */ + MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory); + + /* + * Loop to handle the ValuePerCall protocol (which is also the same + * behavior needed in the generic ExecEvalExpr path). + */ + for (;;) + { + Datum result; + + CHECK_FOR_INTERRUPTS(); + + /* + * Reset per-tuple memory context before each call of the function or + * expression. This cleans up any local memory the function may leak + * when called. + */ + ResetExprContext(econtext); + + /* Call the function or expression one time */ + if (!setexpr->elidedFuncState) + { + pgstat_init_function_usage(fcinfo, &fcusage); + + fcinfo->isnull = false; + rsinfo.isDone = ExprSingleResult; + result = FunctionCallInvoke(fcinfo); + + pgstat_end_function_usage(&fcusage, + rsinfo.isDone != ExprMultipleResult); + } + else + { + result = + ExecEvalExpr(setexpr->elidedFuncState, econtext, &fcinfo->isnull); + rsinfo.isDone = ExprSingleResult; + } + + /* Which protocol does function want to use? */ + if (rsinfo.returnMode == SFRM_ValuePerCall) + { + /* + * Check for end of result set. + */ + if (rsinfo.isDone == ExprEndResult) + break; + + /* + * If first time through, build tuplestore for result. For a + * scalar function result type, also make a suitable tupdesc. + */ + if (first_time) + { + MemoryContext oldcontext = + MemoryContextSwitchTo(econtext->ecxt_per_query_memory); + + tupstore = tuplestore_begin_heap(randomAccess, false, work_mem); + rsinfo.setResult = tupstore; + if (!returnsTuple) + { + tupdesc = CreateTemplateTupleDesc(1); + TupleDescInitEntry(tupdesc, + (AttrNumber) 1, + "column", + funcrettype, + -1, + 0); + rsinfo.setDesc = tupdesc; + } + MemoryContextSwitchTo(oldcontext); + } + + /* + * Store current resultset item. + */ + if (returnsTuple) + { + if (!fcinfo->isnull) + { + HeapTupleHeader td = DatumGetHeapTupleHeader(result); + + if (tupdesc == NULL) + { + MemoryContext oldcontext = + MemoryContextSwitchTo(econtext->ecxt_per_query_memory); + + /* + * This is the first non-NULL result from the + * function. Use the type info embedded in the + * rowtype Datum to look up the needed tupdesc. Make + * a copy for the query. + */ + tupdesc = lookup_rowtype_tupdesc_copy(HeapTupleHeaderGetTypeId(td), + HeapTupleHeaderGetTypMod(td)); + rsinfo.setDesc = tupdesc; + MemoryContextSwitchTo(oldcontext); + } + else + { + /* + * Verify all later returned rows have same subtype; + * necessary in case the type is RECORD. + */ + if (HeapTupleHeaderGetTypeId(td) != tupdesc->tdtypeid || + HeapTupleHeaderGetTypMod(td) != tupdesc->tdtypmod) + ereport(ERROR, + (errcode(ERRCODE_DATATYPE_MISMATCH), + errmsg("rows returned by function are not all of the same row type"))); + } + + /* + * tuplestore_puttuple needs a HeapTuple not a bare + * HeapTupleHeader, but it doesn't need all the fields. + */ + tmptup.t_len = HeapTupleHeaderGetDatumLength(td); + tmptup.t_data = td; + + tuplestore_puttuple(tupstore, &tmptup); + } + else + { + /* + * NULL result from a tuple-returning function; expand it + * to a row of all nulls. We rely on the expectedDesc to + * form such rows. (Note: this would be problematic if + * tuplestore_putvalues saved the tdtypeid/tdtypmod from + * the provided descriptor, since that might not match + * what we get from the function itself. But it doesn't.) + */ + int natts = expectedDesc->natts; + bool *nullflags; + + nullflags = (bool *) palloc(natts * sizeof(bool)); + memset(nullflags, true, natts * sizeof(bool)); + tuplestore_putvalues(tupstore, expectedDesc, NULL, nullflags); + } + } + else + { + /* Scalar-type case: just store the function result */ + tuplestore_putvalues(tupstore, tupdesc, &result, &fcinfo->isnull); + } + + /* + * Are we done? + */ + if (rsinfo.isDone != ExprMultipleResult) + break; + + /* + * Check that set-returning functions were properly declared. + * (Note: for historical reasons, we don't complain if a non-SRF + * returns ExprEndResult; that's treated as returning NULL.) + */ + if (!returnsSet) + ereport(ERROR, + (errcode(ERRCODE_E_R_I_E_SRF_PROTOCOL_VIOLATED), + errmsg("table-function protocol for value-per-call mode was not followed"))); + } + else if (rsinfo.returnMode == SFRM_Materialize) + { + /* check we're on the same page as the function author */ + if (!first_time || rsinfo.isDone != ExprSingleResult || !returnsSet) + ereport(ERROR, + (errcode(ERRCODE_E_R_I_E_SRF_PROTOCOL_VIOLATED), + errmsg("table-function protocol for materialize mode was not followed"))); + /* Done evaluating the set result */ + break; + } + else + ereport(ERROR, + (errcode(ERRCODE_E_R_I_E_SRF_PROTOCOL_VIOLATED), + errmsg("unrecognized table-function returnMode: %d", + (int) rsinfo.returnMode))); + + first_time = false; + } + +no_function_result: + + /* + * If we got nothing from the function (ie, an empty-set or NULL result), + * we have to create the tuplestore to return, and if it's a + * non-set-returning function then insert a single all-nulls row. As + * above, we depend on the expectedDesc to manufacture the dummy row. + */ + if (rsinfo.setResult == NULL) + { + MemoryContext oldcontext = + MemoryContextSwitchTo(econtext->ecxt_per_query_memory); + + tupstore = tuplestore_begin_heap(randomAccess, false, work_mem); + rsinfo.setResult = tupstore; + MemoryContextSwitchTo(oldcontext); + + if (!returnsSet) + { + int natts = expectedDesc->natts; + bool *nullflags; + + nullflags = (bool *) palloc(natts * sizeof(bool)); + memset(nullflags, true, natts * sizeof(bool)); + tuplestore_putvalues(tupstore, expectedDesc, NULL, nullflags); + } + } + + /* + * 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 (rsinfo.setDesc) + { + tupledesc_match(expectedDesc, rsinfo.setDesc); + + /* + * If it is a dynamically-allocated TupleDesc, free it: it is + * typically allocated in a per-query context, so we must avoid + * leaking it across multiple usages. + */ + if (rsinfo.setDesc->tdrefcount == -1) + FreeTupleDesc(rsinfo.setDesc); + } + + MemoryContextSwitchTo(callerContext); + + /* All done, pass back the tuplestore */ + return rsinfo.setResult; +} + + +/* + * Prepare targetlist SRF function call for execution. + * + * This is used by nodeProjectSet.c. + */ +SetExprState * +ExecInitFunctionResultSet(Expr *expr, + ExprContext *econtext, PlanState *parent) +{ + SetExprState *state = makeNode(SetExprState); + + state->funcReturnsSet = true; + state->expr = expr; + state->func.fn_oid = InvalidOid; + + /* + * Initialize metadata. The expression node could be either a FuncExpr or + * an OpExpr. + */ + if (IsA(expr, FuncExpr)) + { + FuncExpr *func = (FuncExpr *) expr; + + state->args = ExecInitExprList(func->args, parent); + init_sexpr(func->funcid, func->inputcollid, expr, state, parent, + econtext->ecxt_per_query_memory, true, true); + } + else if (IsA(expr, OpExpr)) + { + OpExpr *op = (OpExpr *) expr; + + state->args = ExecInitExprList(op->args, parent); + init_sexpr(op->opfuncid, op->inputcollid, expr, state, parent, + econtext->ecxt_per_query_memory, true, true); + } + else + elog(ERROR, "unrecognized node type: %d", + (int) nodeTag(expr)); + + /* shouldn't get here unless the selected function returns set */ + Assert(state->func.fn_retset); + + return state; +} + +/* + * ExecMakeFunctionResultSet + * + * Evaluate the arguments to a set-returning function and then call the + * function itself. The argument expressions may not contain set-returning + * functions (the planner is supposed to have separated evaluation for those). + * + * This should be called in a short-lived (per-tuple) context, argContext + * needs to live until all rows have been returned (i.e. *isDone set to + * ExprEndResult or ExprSingleResult). + * + * This is used by nodeProjectSet.c. + */ +Datum +ExecMakeFunctionResultSet(SetExprState *fcache, + ExprContext *econtext, + MemoryContext argContext, + bool *isNull, + ExprDoneCond *isDone) +{ + List *arguments; + Datum result; + FunctionCallInfo fcinfo; + PgStat_FunctionCallUsage fcusage; + ReturnSetInfo rsinfo; + bool callit; + int i; + +restart: + + /* Guard against stack overflow due to overly complex expressions */ + check_stack_depth(); + + /* + * If a previous call of the function returned a set result in the form of + * a tuplestore, continue reading rows from the tuplestore until it's + * empty. + */ + if (fcache->funcResultStore) + { + TupleTableSlot *slot = fcache->funcResultSlot; + MemoryContext oldContext; + bool foundTup; + + /* + * Have to make sure tuple in slot lives long enough, otherwise + * clearing the slot could end up trying to free something already + * freed. + */ + oldContext = MemoryContextSwitchTo(slot->tts_mcxt); + foundTup = tuplestore_gettupleslot(fcache->funcResultStore, true, false, + fcache->funcResultSlot); + MemoryContextSwitchTo(oldContext); + + if (foundTup) + { + *isDone = ExprMultipleResult; + if (fcache->funcReturnsTuple) + { + /* We must return the whole tuple as a Datum. */ + *isNull = false; + return ExecFetchSlotHeapTupleDatum(fcache->funcResultSlot); + } + else + { + /* Extract the first column and return it as a scalar. */ + return slot_getattr(fcache->funcResultSlot, 1, isNull); + } + } + /* Exhausted the tuplestore, so clean up */ + tuplestore_end(fcache->funcResultStore); + fcache->funcResultStore = NULL; + *isDone = ExprEndResult; + *isNull = true; + return (Datum) 0; + } + + /* + * arguments is a list of expressions to evaluate before passing to the + * function manager. We skip the evaluation if it was already done in the + * previous call (ie, we are continuing the evaluation of a set-valued + * function). Otherwise, collect the current argument values into fcinfo. + * + * The arguments have to live in a context that lives at least until all + * rows from this SRF have been returned, otherwise ValuePerCall SRFs + * would reference freed memory after the first returned row. + */ + fcinfo = fcache->fcinfo; + arguments = fcache->args; + if (!fcache->setArgsValid) + { + MemoryContext oldContext = MemoryContextSwitchTo(argContext); + + ExecEvalFuncArgs(fcinfo, arguments, econtext); + MemoryContextSwitchTo(oldContext); + } + else + { + /* Reset flag (we may set it again below) */ + fcache->setArgsValid = false; + } + + /* + * Now call the function, passing the evaluated parameter values. + */ + + /* Prepare a resultinfo node for communication. */ + fcinfo->resultinfo = (Node *) &rsinfo; + rsinfo.type = T_ReturnSetInfo; + rsinfo.econtext = econtext; + rsinfo.expectedDesc = fcache->funcResultDesc; + rsinfo.allowedModes = (int) (SFRM_ValuePerCall | SFRM_Materialize); + /* note we do not set SFRM_Materialize_Random or _Preferred */ + rsinfo.returnMode = SFRM_ValuePerCall; + /* isDone is filled below */ + rsinfo.setResult = NULL; + rsinfo.setDesc = NULL; + + /* + * If function is strict, and there are any NULL arguments, skip calling + * the function. + */ + callit = true; + if (fcache->func.fn_strict) + { + for (i = 0; i < fcinfo->nargs; i++) + { + if (fcinfo->args[i].isnull) + { + callit = false; + break; + } + } + } + + if (callit) + { + pgstat_init_function_usage(fcinfo, &fcusage); + + fcinfo->isnull = false; + rsinfo.isDone = ExprSingleResult; + result = FunctionCallInvoke(fcinfo); + *isNull = fcinfo->isnull; + *isDone = rsinfo.isDone; + + pgstat_end_function_usage(&fcusage, + rsinfo.isDone != ExprMultipleResult); + } + else + { + /* for a strict SRF, result for NULL is an empty set */ + result = (Datum) 0; + *isNull = true; + *isDone = ExprEndResult; + } + + /* Which protocol does function want to use? */ + if (rsinfo.returnMode == SFRM_ValuePerCall) + { + if (*isDone != ExprEndResult) + { + /* + * Save the current argument values to re-use on the next call. + */ + if (*isDone == ExprMultipleResult) + { + fcache->setArgsValid = true; + /* Register cleanup callback if we didn't already */ + if (!fcache->shutdown_reg) + { + RegisterExprContextCallback(econtext, + ShutdownSetExpr, + PointerGetDatum(fcache)); + fcache->shutdown_reg = true; + } + } + } + } + else if (rsinfo.returnMode == SFRM_Materialize) + { + /* check we're on the same page as the function author */ + if (rsinfo.isDone != ExprSingleResult) + ereport(ERROR, + (errcode(ERRCODE_E_R_I_E_SRF_PROTOCOL_VIOLATED), + errmsg("table-function protocol for materialize mode was not followed"))); + if (rsinfo.setResult != NULL) + { + /* prepare to return values from the tuplestore */ + ExecPrepareTuplestoreResult(fcache, econtext, + rsinfo.setResult, + rsinfo.setDesc); + /* loop back to top to start returning from tuplestore */ + goto restart; + } + /* if setResult was left null, treat it as empty set */ + *isDone = ExprEndResult; + *isNull = true; + result = (Datum) 0; + } + else + ereport(ERROR, + (errcode(ERRCODE_E_R_I_E_SRF_PROTOCOL_VIOLATED), + errmsg("unrecognized table-function returnMode: %d", + (int) rsinfo.returnMode))); + + return result; +} + + +/* + * init_sexpr - initialize a SetExprState node during first use + */ +static void +init_sexpr(Oid foid, Oid input_collation, Expr *node, + SetExprState *sexpr, PlanState *parent, + MemoryContext sexprCxt, bool allowSRF, bool needDescForSRF) +{ + AclResult aclresult; + size_t numargs = list_length(sexpr->args); + + /* Check permission to call function */ + aclresult = pg_proc_aclcheck(foid, GetUserId(), ACL_EXECUTE); + if (aclresult != ACLCHECK_OK) + aclcheck_error(aclresult, OBJECT_FUNCTION, get_func_name(foid)); + InvokeFunctionExecuteHook(foid); + + /* + * Safety check on nargs. Under normal circumstances this should never + * fail, as parser should check sooner. But possibly it might fail if + * server has been compiled with FUNC_MAX_ARGS smaller than some functions + * declared in pg_proc? + */ + if (list_length(sexpr->args) > FUNC_MAX_ARGS) + ereport(ERROR, + (errcode(ERRCODE_TOO_MANY_ARGUMENTS), + errmsg_plural("cannot pass more than %d argument to a function", + "cannot pass more than %d arguments to a function", + FUNC_MAX_ARGS, + FUNC_MAX_ARGS))); + + /* Set up the primary fmgr lookup information */ + fmgr_info_cxt(foid, &(sexpr->func), sexprCxt); + fmgr_info_set_expr((Node *) sexpr->expr, &(sexpr->func)); + + /* Initialize the function call parameter struct as well */ + sexpr->fcinfo = + (FunctionCallInfo) palloc(SizeForFunctionCallInfo(numargs)); + InitFunctionCallInfoData(*sexpr->fcinfo, &(sexpr->func), + numargs, + input_collation, NULL, NULL); + + /* If function returns set, check if that's allowed by caller */ + if (sexpr->func.fn_retset && !allowSRF) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("set-valued function called in context that cannot accept a set"), + parent ? executor_errposition(parent->state, + exprLocation((Node *) node)) : 0)); + + /* Otherwise, caller should have marked the sexpr correctly */ + Assert(sexpr->func.fn_retset == sexpr->funcReturnsSet); + + /* If function returns set, prepare expected tuple descriptor */ + if (sexpr->func.fn_retset && needDescForSRF) + { + TypeFuncClass functypclass; + Oid funcrettype; + TupleDesc tupdesc; + MemoryContext oldcontext; + + functypclass = get_expr_result_type(sexpr->func.fn_expr, + &funcrettype, + &tupdesc); + + /* Must save tupdesc in sexpr's context */ + oldcontext = MemoryContextSwitchTo(sexprCxt); + + if (functypclass == TYPEFUNC_COMPOSITE || + functypclass == TYPEFUNC_COMPOSITE_DOMAIN) + { + /* Composite data type, e.g. a table's row type */ + Assert(tupdesc); + /* Must copy it out of typcache for safety */ + sexpr->funcResultDesc = CreateTupleDescCopy(tupdesc); + sexpr->funcReturnsTuple = true; + } + else if (functypclass == TYPEFUNC_SCALAR) + { + /* Base data type, i.e. scalar */ + tupdesc = CreateTemplateTupleDesc(1); + TupleDescInitEntry(tupdesc, + (AttrNumber) 1, + NULL, + funcrettype, + -1, + 0); + sexpr->funcResultDesc = tupdesc; + sexpr->funcReturnsTuple = false; + } + else if (functypclass == TYPEFUNC_RECORD) + { + /* This will work if function doesn't need an expectedDesc */ + sexpr->funcResultDesc = NULL; + sexpr->funcReturnsTuple = true; + } + else + { + /* Else, we will fail if function needs an expectedDesc */ + sexpr->funcResultDesc = NULL; + } + + MemoryContextSwitchTo(oldcontext); + } + else + sexpr->funcResultDesc = NULL; + + /* Initialize additional state */ + sexpr->funcResultStore = NULL; + sexpr->funcResultSlot = NULL; + sexpr->shutdown_reg = false; +} + +/* + * callback function in case a SetExprState needs to be shut down before it + * has been run to completion + */ +static void +ShutdownSetExpr(Datum arg) +{ + SetExprState *sexpr = castNode(SetExprState, DatumGetPointer(arg)); + + /* If we have a slot, make sure it's let go of any tuplestore pointer */ + if (sexpr->funcResultSlot) + ExecClearTuple(sexpr->funcResultSlot); + + /* Release any open tuplestore */ + if (sexpr->funcResultStore) + tuplestore_end(sexpr->funcResultStore); + sexpr->funcResultStore = NULL; + + /* Clear any active set-argument state */ + sexpr->setArgsValid = false; + + /* execUtils will deregister the callback... */ + sexpr->shutdown_reg = false; +} + +/* + * Evaluate arguments for a function. + */ +static void +ExecEvalFuncArgs(FunctionCallInfo fcinfo, + List *argList, + ExprContext *econtext) +{ + int i; + ListCell *arg; + + i = 0; + foreach(arg, argList) + { + ExprState *argstate = (ExprState *) lfirst(arg); + + fcinfo->args[i].value = ExecEvalExpr(argstate, + econtext, + &fcinfo->args[i].isnull); + i++; + } + + Assert(i == fcinfo->nargs); +} + +/* + * ExecPrepareTuplestoreResult + * + * Subroutine for ExecMakeFunctionResultSet: prepare to extract rows from a + * tuplestore function result. We must set up a funcResultSlot (unless + * already done in a previous call cycle) and verify that the function + * returned the expected tuple descriptor. + */ +static void +ExecPrepareTuplestoreResult(SetExprState *sexpr, + ExprContext *econtext, + Tuplestorestate *resultStore, + TupleDesc resultDesc) +{ + sexpr->funcResultStore = resultStore; + + if (sexpr->funcResultSlot == NULL) + { + /* Create a slot so we can read data out of the tuplestore */ + TupleDesc slotDesc; + MemoryContext oldcontext; + + oldcontext = MemoryContextSwitchTo(sexpr->func.fn_mcxt); + + /* + * If we were not able to determine the result rowtype from context, + * and the function didn't return a tupdesc, we have to fail. + */ + if (sexpr->funcResultDesc) + slotDesc = sexpr->funcResultDesc; + else if (resultDesc) + { + /* don't assume resultDesc is long-lived */ + slotDesc = CreateTupleDescCopy(resultDesc); + } + else + { + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("function returning setof record called in " + "context that cannot accept type record"))); + slotDesc = NULL; /* keep compiler quiet */ + } + + sexpr->funcResultSlot = MakeSingleTupleTableSlot(slotDesc, + &TTSOpsMinimalTuple); + MemoryContextSwitchTo(oldcontext); + } + + /* + * 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 (resultDesc) + { + if (sexpr->funcResultDesc) + tupledesc_match(sexpr->funcResultDesc, resultDesc); + + /* + * If it is a dynamically-allocated TupleDesc, free it: it is + * typically allocated in a per-query context, so we must avoid + * leaking it across multiple usages. + */ + if (resultDesc->tdrefcount == -1) + FreeTupleDesc(resultDesc); + } + + /* Register cleanup callback if we didn't already */ + if (!sexpr->shutdown_reg) + { + RegisterExprContextCallback(econtext, + ShutdownSetExpr, + PointerGetDatum(sexpr)); + sexpr->shutdown_reg = true; + } +} + +/* + * Check that function result tuple type (src_tupdesc) matches or can + * be considered to match what the query expects (dst_tupdesc). If + * they don't match, ereport. + * + * 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 void +tupledesc_match(TupleDesc dst_tupdesc, TupleDesc src_tupdesc) +{ + int i; + + if (dst_tupdesc->natts != src_tupdesc->natts) + ereport(ERROR, + (errcode(ERRCODE_DATATYPE_MISMATCH), + errmsg("function return row and query-specified return row do not match"), + errdetail_plural("Returned row contains %d attribute, but query expects %d.", + "Returned row contains %d attributes, but query expects %d.", + src_tupdesc->natts, + src_tupdesc->natts, dst_tupdesc->natts))); + + for (i = 0; i < dst_tupdesc->natts; i++) + { + Form_pg_attribute dattr = TupleDescAttr(dst_tupdesc, i); + Form_pg_attribute sattr = TupleDescAttr(src_tupdesc, i); + + if (IsBinaryCoercible(sattr->atttypid, dattr->atttypid)) + continue; /* no worries */ + if (!dattr->attisdropped) + ereport(ERROR, + (errcode(ERRCODE_DATATYPE_MISMATCH), + errmsg("function return row and query-specified return row do not match"), + errdetail("Returned type %s at ordinal position %d, but query expects %s.", + format_type_be(sattr->atttypid), + i + 1, + format_type_be(dattr->atttypid)))); + + if (dattr->attlen != sattr->attlen || + dattr->attalign != sattr->attalign) + ereport(ERROR, + (errcode(ERRCODE_DATATYPE_MISMATCH), + errmsg("function return row and query-specified return row do not match"), + errdetail("Physical storage mismatch on dropped attribute at ordinal position %d.", + i + 1))); + } +} |