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functions.c
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Tom Lane authored
DestReceiver created during postquel_start needs to be destroyed during postquel_end. In a moment of brain fade I had assumed this would be taken care of by FreeQueryDesc, but it's not (and shouldn't be).
Tom Lane authoredDestReceiver created during postquel_start needs to be destroyed during postquel_end. In a moment of brain fade I had assumed this would be taken care of by FreeQueryDesc, but it's not (and shouldn't be).
functions.c 37.60 KiB
/*-------------------------------------------------------------------------
*
* functions.c
* Execution of SQL-language functions
*
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.129 2008/11/27 00:10:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/xact.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "executor/functions.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "parser/parse_coerce.h"
#include "tcop/utility.h"
#include "utils/builtins.h"
#include "utils/datum.h"
#include "utils/lsyscache.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
/*
* Specialized DestReceiver for collecting query output in a SQL function
*/
typedef struct
{
DestReceiver pub; /* publicly-known function pointers */
Tuplestorestate *tstore; /* where to put result tuples */
MemoryContext cxt; /* context containing tstore */
JunkFilter *filter; /* filter to convert tuple type */
} DR_sqlfunction;
/*
* We have an execution_state record for each query in a function. Each
* record contains a plantree for its query. If the query is currently in
* F_EXEC_RUN state then there's a QueryDesc too.
*/
typedef enum
{
F_EXEC_START, F_EXEC_RUN, F_EXEC_DONE
} ExecStatus;
typedef struct execution_state
{
struct execution_state *next;
ExecStatus status;
bool setsResult; /* true if this query produces func's result */
bool lazyEval; /* true if should fetch one row at a time */
Node *stmt; /* PlannedStmt or utility statement */
QueryDesc *qd; /* null unless status == RUN */
} execution_state;
/*
* An SQLFunctionCache record is built during the first call,
* and linked to from the fn_extra field of the FmgrInfo struct.
* * Note that currently this has only the lifespan of the calling query.
* Someday we might want to consider caching the parse/plan results longer
* than that.
*/
typedef struct
{
char *src; /* function body text (for error msgs) */
Oid *argtypes; /* resolved types of arguments */
Oid rettype; /* actual return type */
int16 typlen; /* length of the return type */
bool typbyval; /* true if return type is pass by value */
bool returnsSet; /* true if returning multiple rows */
bool returnsTuple; /* true if returning whole tuple result */
bool shutdown_reg; /* true if registered shutdown callback */
bool readonly_func; /* true to run in "read only" mode */
bool lazyEval; /* true if using lazyEval for result query */
ParamListInfo paramLI; /* Param list representing current args */
Tuplestorestate *tstore; /* where we accumulate result tuples */
JunkFilter *junkFilter; /* will be NULL if function returns VOID */
/* head of linked list of execution_state records */
execution_state *func_state;
} SQLFunctionCache;
typedef SQLFunctionCache *SQLFunctionCachePtr;
/* non-export function prototypes */
static execution_state *init_execution_state(List *queryTree_list,
SQLFunctionCachePtr fcache,
bool lazyEvalOK);
static void init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK);
static void postquel_start(execution_state *es, SQLFunctionCachePtr fcache);
static bool postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache);
static void postquel_end(execution_state *es);
static void postquel_sub_params(SQLFunctionCachePtr fcache,
FunctionCallInfo fcinfo);
static Datum postquel_get_single_result(TupleTableSlot *slot,
FunctionCallInfo fcinfo,
SQLFunctionCachePtr fcache,
MemoryContext resultcontext);
static void sql_exec_error_callback(void *arg);
static void ShutdownSQLFunction(Datum arg);
static void sqlfunction_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
static void sqlfunction_receive(TupleTableSlot *slot, DestReceiver *self);
static void sqlfunction_shutdown(DestReceiver *self);
static void sqlfunction_destroy(DestReceiver *self);
/* Set up the list of per-query execution_state records for a SQL function */
static execution_state *
init_execution_state(List *queryTree_list,
SQLFunctionCachePtr fcache,
bool lazyEvalOK)
{
execution_state *firstes = NULL;
execution_state *preves = NULL;
execution_state *lasttages = NULL;
ListCell *qtl_item;
foreach(qtl_item, queryTree_list)
{
Query *queryTree = (Query *) lfirst(qtl_item);
Node *stmt;
execution_state *newes;
Assert(IsA(queryTree, Query));
if (queryTree->commandType == CMD_UTILITY)
stmt = queryTree->utilityStmt;
else
stmt = (Node *) pg_plan_query(queryTree, 0, NULL);
/* Precheck all commands for validity in a function */
if (IsA(stmt, TransactionStmt))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
/* translator: %s is a SQL statement name */
errmsg("%s is not allowed in a SQL function",
CreateCommandTag(stmt))));
if (fcache->readonly_func && !CommandIsReadOnly(stmt))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
/* translator: %s is a SQL statement name */
errmsg("%s is not allowed in a non-volatile function",
CreateCommandTag(stmt))));
newes = (execution_state *) palloc(sizeof(execution_state));
if (preves)
preves->next = newes;
else
firstes = newes;
newes->next = NULL;
newes->status = F_EXEC_START;
newes->setsResult = false; /* might change below */
newes->lazyEval = false; /* might change below */
newes->stmt = stmt;
newes->qd = NULL;
if (queryTree->canSetTag)
lasttages = newes;
preves = newes;
}
/*
* Mark the last canSetTag query as delivering the function result;
* then, if it is a plain SELECT, mark it for lazy evaluation.
* If it's not a SELECT we must always run it to completion.
*
* Note: at some point we might add additional criteria for whether to use
* lazy eval. However, we should prefer to use it whenever the function
* doesn't return set, since fetching more than one row is useless in that
* case.
*
* Note: don't set setsResult if the function returns VOID, as evidenced
* by not having made a junkfilter. This ensures we'll throw away any
* output from a utility statement that check_sql_fn_retval deemed to
* not have output.
*/
if (lasttages && fcache->junkFilter)
{
lasttages->setsResult = true;
if (lazyEvalOK &&
IsA(lasttages->stmt, PlannedStmt))
{
PlannedStmt *ps = (PlannedStmt *) lasttages->stmt;
if (ps->commandType == CMD_SELECT &&
ps->utilityStmt == NULL &&
ps->intoClause == NULL)
fcache->lazyEval = lasttages->lazyEval = true;
}
}
return firstes;
}
/* Initialize the SQLFunctionCache for a SQL function */
static void
init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK)
{
Oid foid = finfo->fn_oid;
Oid rettype;
HeapTuple procedureTuple;
Form_pg_proc procedureStruct;
SQLFunctionCachePtr fcache;
Oid *argOidVect;
int nargs;
List *queryTree_list;
Datum tmp;
bool isNull;
fcache = (SQLFunctionCachePtr) palloc0(sizeof(SQLFunctionCache));
/*
* get the procedure tuple corresponding to the given function Oid
*/
procedureTuple = SearchSysCache(PROCOID,
ObjectIdGetDatum(foid),
0, 0, 0);
if (!HeapTupleIsValid(procedureTuple))
elog(ERROR, "cache lookup failed for function %u", foid);
procedureStruct = (Form_pg_proc) GETSTRUCT(procedureTuple);
/*
* get the result type from the procedure tuple, and check for polymorphic
* result type; if so, find out the actual result type.
*/
rettype = procedureStruct->prorettype;
if (IsPolymorphicType(rettype))
{
rettype = get_fn_expr_rettype(finfo);
if (rettype == InvalidOid) /* this probably should not happen */
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("could not determine actual result type for function declared to return type %s",
format_type_be(procedureStruct->prorettype))));
}
fcache->rettype = rettype;
/* Fetch the typlen and byval info for the result type */
get_typlenbyval(rettype, &fcache->typlen, &fcache->typbyval);
/* Remember whether we're returning setof something */
fcache->returnsSet = procedureStruct->proretset;
/* Remember if function is STABLE/IMMUTABLE */
fcache->readonly_func =
(procedureStruct->provolatile != PROVOLATILE_VOLATILE);
/*
* We need the actual argument types to pass to the parser.
*/
nargs = procedureStruct->pronargs;
if (nargs > 0)
{
int argnum;
argOidVect = (Oid *) palloc(nargs * sizeof(Oid));
memcpy(argOidVect,
procedureStruct->proargtypes.values, nargs * sizeof(Oid));
/* Resolve any polymorphic argument types */
for (argnum = 0; argnum < nargs; argnum++)
{
Oid argtype = argOidVect[argnum];
if (IsPolymorphicType(argtype))
{
argtype = get_fn_expr_argtype(finfo, argnum);
if (argtype == InvalidOid)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("could not determine actual type of argument declared %s",
format_type_be(argOidVect[argnum]))));
argOidVect[argnum] = argtype;
}
}
}
else
argOidVect = NULL;
fcache->argtypes = argOidVect;
/*
* And of course we need the function body text.
*/
tmp = SysCacheGetAttr(PROCOID,
procedureTuple,
Anum_pg_proc_prosrc,
&isNull);
if (isNull)
elog(ERROR, "null prosrc for function %u", foid);
fcache->src = TextDatumGetCString(tmp);
/*
* Parse and rewrite the queries in the function text.
*/
queryTree_list = pg_parse_and_rewrite(fcache->src, argOidVect, nargs);
/*
* Check that the function returns the type it claims to. Although in
* simple cases this was already done when the function was defined, we
* have to recheck because database objects used in the function's queries
* might have changed type. We'd have to do it anyway if the function had
* any polymorphic arguments.
*
* Note: we set fcache->returnsTuple according to whether we are returning
* the whole tuple result or just a single column. In the latter case we
* clear returnsTuple because we need not act different from the scalar
* result case, even if it's a rowtype column. (However, we have to
* force lazy eval mode in that case; otherwise we'd need extra code to
* expand the rowtype column into multiple columns, since we have no
* way to notify the caller that it should do that.)
*
* check_sql_fn_retval will also construct a JunkFilter we can use to
* coerce the returned rowtype to the desired form (unless the result type
* is VOID, in which case there's nothing to coerce to).
*/
fcache->returnsTuple = check_sql_fn_retval(foid,
rettype,
queryTree_list,
false,
&fcache->junkFilter);
if (fcache->returnsTuple)
{
/* Make sure output rowtype is properly blessed */
BlessTupleDesc(fcache->junkFilter->jf_resultSlot->tts_tupleDescriptor);
}
else if (fcache->returnsSet && type_is_rowtype(fcache->rettype))
{ /*
* Returning rowtype as if it were scalar --- materialize won't work.
* Right now it's sufficient to override any caller preference for
* materialize mode, but to add more smarts in init_execution_state
* about this, we'd probably need a three-way flag instead of bool.
*/
lazyEvalOK = true;
}
/* Finally, plan the queries */
fcache->func_state = init_execution_state(queryTree_list,
fcache,
lazyEvalOK);
ReleaseSysCache(procedureTuple);
finfo->fn_extra = (void *) fcache;
}
/* Start up execution of one execution_state node */
static void
postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
{
Snapshot snapshot;
DestReceiver *dest;
Assert(es->qd == NULL);
/*
* In a read-only function, use the surrounding query's snapshot;
* otherwise take a new snapshot for each query. The snapshot should
* include a fresh command ID so that all work to date in this transaction
* is visible.
*/
if (fcache->readonly_func)
snapshot = GetActiveSnapshot();
else
{
CommandCounterIncrement();
snapshot = GetTransactionSnapshot();
}
/*
* If this query produces the function result, send its output to the
* tuplestore; else discard any output.
*/
if (es->setsResult)
{
DR_sqlfunction *myState;
dest = CreateDestReceiver(DestSQLFunction, NULL);
/* pass down the needed info to the dest receiver routines */
myState = (DR_sqlfunction *) dest;
Assert(myState->pub.mydest == DestSQLFunction);
myState->tstore = fcache->tstore;
myState->cxt = CurrentMemoryContext;
myState->filter = fcache->junkFilter;
}
else
dest = None_Receiver;
if (IsA(es->stmt, PlannedStmt))
es->qd = CreateQueryDesc((PlannedStmt *) es->stmt,
snapshot, InvalidSnapshot,
dest,
fcache->paramLI, false);
else
es->qd = CreateUtilityQueryDesc(es->stmt,
snapshot,
dest, fcache->paramLI);
/* We assume we don't need to set up ActiveSnapshot for ExecutorStart */
/* Utility commands don't need Executor. */
if (es->qd->utilitystmt == NULL)
{
/*
* Only set up to collect queued triggers if it's not a SELECT. This
* isn't just an optimization, but is necessary in case a SELECT
* returns multiple rows to caller --- we mustn't exit from the
* function execution with a stacked AfterTrigger level still active.
*/
if (es->qd->operation != CMD_SELECT)
AfterTriggerBeginQuery();
ExecutorStart(es->qd, 0);
}
es->status = F_EXEC_RUN;
}
/* Run one execution_state; either to completion or to first result row */
/* Returns true if we ran to completion */
static bool
postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache)
{
bool result;
/* Make our snapshot the active one for any called functions */
PushActiveSnapshot(es->qd->snapshot);
if (es->qd->utilitystmt)
{
/* ProcessUtility needs the PlannedStmt for DECLARE CURSOR */
ProcessUtility((es->qd->plannedstmt ?
(Node *) es->qd->plannedstmt :
es->qd->utilitystmt),
fcache->src,
es->qd->params,
false, /* not top level */
es->qd->dest,
NULL);
result = true; /* never stops early */
}
else
{
/* Run regular commands to completion unless lazyEval */
long count = (es->lazyEval) ? 1L : 0L;
ExecutorRun(es->qd, ForwardScanDirection, count);
/*
* If we requested run to completion OR there was no tuple returned,
* command must be complete.
*/
result = (count == 0L || es->qd->estate->es_processed == 0);
}
PopActiveSnapshot();
return result;
}
/* Shut down execution of one execution_state node */
static void
postquel_end(execution_state *es)
{
/* mark status done to ensure we don't do ExecutorEnd twice */
es->status = F_EXEC_DONE;
/* Utility commands don't need Executor. */
if (es->qd->utilitystmt == NULL)
{
/* Make our snapshot the active one for any called functions */
PushActiveSnapshot(es->qd->snapshot);
if (es->qd->operation != CMD_SELECT)
AfterTriggerEndQuery(es->qd->estate);
ExecutorEnd(es->qd);
PopActiveSnapshot();
}
(*es->qd->dest->rDestroy) (es->qd->dest);
FreeQueryDesc(es->qd);
es->qd = NULL;
}
/* Build ParamListInfo array representing current arguments */
static void
postquel_sub_params(SQLFunctionCachePtr fcache,
FunctionCallInfo fcinfo)
{
int nargs = fcinfo->nargs;
if (nargs > 0)
{
ParamListInfo paramLI;
int i;
if (fcache->paramLI == NULL)
{
/* sizeof(ParamListInfoData) includes the first array element */
paramLI = (ParamListInfo) palloc(sizeof(ParamListInfoData) +
(nargs - 1) *sizeof(ParamExternData));
paramLI->numParams = nargs;
fcache->paramLI = paramLI;
}
else
{
paramLI = fcache->paramLI;
Assert(paramLI->numParams == nargs);
}
for (i = 0; i < nargs; i++)
{
ParamExternData *prm = ¶mLI->params[i];
prm->value = fcinfo->arg[i];
prm->isnull = fcinfo->argnull[i];
prm->pflags = 0;
prm->ptype = fcache->argtypes[i];
}
}
else
fcache->paramLI = NULL;
}
/*
* Extract the SQL function's value from a single result row. This is used
* both for scalar (non-set) functions and for each row of a lazy-eval set
* result.
*/
static Datum
postquel_get_single_result(TupleTableSlot *slot,
FunctionCallInfo fcinfo,
SQLFunctionCachePtr fcache,
MemoryContext resultcontext)
{ Datum value;
MemoryContext oldcontext;
/*
* Set up to return the function value. For pass-by-reference datatypes,
* be sure to allocate the result in resultcontext, not the current memory
* context (which has query lifespan). We can't leave the data in the
* TupleTableSlot because we intend to clear the slot before returning.
*/
oldcontext = MemoryContextSwitchTo(resultcontext);
if (fcache->returnsTuple)
{
/* We must return the whole tuple as a Datum. */
fcinfo->isnull = false;
value = ExecFetchSlotTupleDatum(slot);
value = datumCopy(value, fcache->typbyval, fcache->typlen);
}
else
{
/*
* Returning a scalar, which we have to extract from the first column
* of the SELECT result, and then copy into result context if needed.
*/
value = slot_getattr(slot, 1, &(fcinfo->isnull));
if (!fcinfo->isnull)
value = datumCopy(value, fcache->typbyval, fcache->typlen);
}
MemoryContextSwitchTo(oldcontext);
return value;
}
/*
* fmgr_sql: function call manager for SQL functions
*/
Datum
fmgr_sql(PG_FUNCTION_ARGS)
{
MemoryContext oldcontext;
SQLFunctionCachePtr fcache;
ErrorContextCallback sqlerrcontext;
bool randomAccess;
bool lazyEvalOK;
execution_state *es;
TupleTableSlot *slot;
Datum result;
/*
* Switch to context in which the fcache lives. This ensures that
* parsetrees, plans, etc, will have sufficient lifetime. The
* sub-executor is responsible for deleting per-tuple information.
*/
oldcontext = MemoryContextSwitchTo(fcinfo->flinfo->fn_mcxt);
/*
* Setup error traceback support for ereport()
*/
sqlerrcontext.callback = sql_exec_error_callback;
sqlerrcontext.arg = fcinfo->flinfo;
sqlerrcontext.previous = error_context_stack;
error_context_stack = &sqlerrcontext;
/* Check call context */
if (fcinfo->flinfo->fn_retset)
{
ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
/*
* For simplicity, we require callers to support both set eval modes.
* There are cases where we must use one or must use the other, and
* it's not really worthwhile to postpone the check till we know.
*/
if (!rsi || !IsA(rsi, ReturnSetInfo) ||
(rsi->allowedModes & SFRM_ValuePerCall) == 0 ||
(rsi->allowedModes & SFRM_Materialize) == 0 ||
rsi->expectedDesc == NULL)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("set-valued function called in context that cannot accept a set")));
randomAccess = rsi->allowedModes & SFRM_Materialize_Random;
lazyEvalOK = !(rsi->allowedModes & SFRM_Materialize_Preferred);
}
else
{
randomAccess = false;
lazyEvalOK = true;
}
/*
* Initialize fcache (build plans) if first time through.
*/
fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
if (fcache == NULL)
{
init_sql_fcache(fcinfo->flinfo, lazyEvalOK);
fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
}
es = fcache->func_state;
/*
* Convert params to appropriate format if starting a fresh execution. (If
* continuing execution, we can re-use prior params.)
*/
if (es && es->status == F_EXEC_START)
postquel_sub_params(fcache, fcinfo);
/*
* Build tuplestore to hold results, if we don't have one already.
* Note it's in the query-lifespan context.
*/
if (!fcache->tstore)
fcache->tstore = tuplestore_begin_heap(randomAccess, false, work_mem);
/*
* Find first unfinished query in function.
*/
while (es && es->status == F_EXEC_DONE)
es = es->next;
/*
* Execute each command in the function one after another until we either
* run out of commands or get a result row from a lazily-evaluated SELECT.
*/
while (es)
{
bool completed;
if (es->status == F_EXEC_START)
postquel_start(es, fcache);
completed = postquel_getnext(es, fcache);
/*
* If we ran the command to completion, we can shut it down now.
* Any row(s) we need to return are safely stashed in the tuplestore,
* and we want to be sure that, for example, AFTER triggers get fired
* before we return anything. Also, if the function doesn't return * set, we can shut it down anyway because it must be a SELECT and
* we don't care about fetching any more result rows.
*/
if (completed || !fcache->returnsSet)
postquel_end(es);
/*
* Break from loop if we didn't shut down (implying we got a
* lazily-evaluated row). Otherwise we'll press on till the
* whole function is done, relying on the tuplestore to keep hold
* of the data to eventually be returned. This is necessary since
* an INSERT/UPDATE/DELETE RETURNING that sets the result might be
* followed by additional rule-inserted commands, and we want to
* finish doing all those commands before we return anything.
*/
if (es->status != F_EXEC_DONE)
break;
es = es->next;
}
/*
* The tuplestore now contains whatever row(s) we are supposed to return.
*/
if (fcache->returnsSet)
{
ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
if (es)
{
/*
* If we stopped short of being done, we must have a lazy-eval row.
*/
Assert(es->lazyEval);
/* Re-use the junkfilter's output slot to fetch back the tuple */
Assert(fcache->junkFilter);
slot = fcache->junkFilter->jf_resultSlot;
if (!tuplestore_gettupleslot(fcache->tstore, true, slot))
elog(ERROR, "failed to fetch lazy-eval tuple");
/* Extract the result as a datum, and copy out from the slot */
result = postquel_get_single_result(slot, fcinfo,
fcache, oldcontext);
/* Clear the tuplestore, but keep it for next time */
/* NB: this might delete the slot's content, but we don't care */
tuplestore_clear(fcache->tstore);
/*
* Let caller know we're not finished.
*/
rsi->isDone = ExprMultipleResult;
/*
* Ensure we will get shut down cleanly if the exprcontext is not
* run to completion.
*/
if (!fcache->shutdown_reg)
{
RegisterExprContextCallback(rsi->econtext,
ShutdownSQLFunction,
PointerGetDatum(fcache));
fcache->shutdown_reg = true;
}
}
else if (fcache->lazyEval)
{
/*
* We are done with a lazy evaluation. Clean up.
*/
tuplestore_clear(fcache->tstore);
/* * Let caller know we're finished.
*/
rsi->isDone = ExprEndResult;
fcinfo->isnull = true;
result = (Datum) 0;
/* Deregister shutdown callback, if we made one */
if (fcache->shutdown_reg)
{
UnregisterExprContextCallback(rsi->econtext,
ShutdownSQLFunction,
PointerGetDatum(fcache));
fcache->shutdown_reg = false;
}
}
else
{
/*
* We are done with a non-lazy evaluation. Return whatever is
* in the tuplestore. (It is now caller's responsibility to
* free the tuplestore when done.)
*/
rsi->returnMode = SFRM_Materialize;
rsi->setResult = fcache->tstore;
fcache->tstore = NULL;
/* must copy desc because execQual will free it */
if (fcache->junkFilter)
rsi->setDesc = CreateTupleDescCopy(fcache->junkFilter->jf_cleanTupType);
fcinfo->isnull = true;
result = (Datum) 0;
/* Deregister shutdown callback, if we made one */
if (fcache->shutdown_reg)
{
UnregisterExprContextCallback(rsi->econtext,
ShutdownSQLFunction,
PointerGetDatum(fcache));
fcache->shutdown_reg = false;
}
}
}
else
{
/*
* Non-set function. If we got a row, return it; else return NULL.
*/
if (fcache->junkFilter)
{
/* Re-use the junkfilter's output slot to fetch back the tuple */
slot = fcache->junkFilter->jf_resultSlot;
if (tuplestore_gettupleslot(fcache->tstore, true, slot))
result = postquel_get_single_result(slot, fcinfo,
fcache, oldcontext);
else
{
fcinfo->isnull = true;
result = (Datum) 0;
}
}
else
{
/* Should only get here for VOID functions */
Assert(fcache->rettype == VOIDOID);
fcinfo->isnull = true;
result = (Datum) 0;
}
/* Clear the tuplestore, but keep it for next time */ tuplestore_clear(fcache->tstore);
}
/*
* If we've gone through every command in the function, we are done.
* Reset the execution states to start over again on next call.
*/
if (es == NULL)
{
es = fcache->func_state;
while (es)
{
es->status = F_EXEC_START;
es = es->next;
}
}
error_context_stack = sqlerrcontext.previous;
MemoryContextSwitchTo(oldcontext);
return result;
}
/*
* error context callback to let us supply a call-stack traceback
*/
static void
sql_exec_error_callback(void *arg)
{
FmgrInfo *flinfo = (FmgrInfo *) arg;
SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) flinfo->fn_extra;
HeapTuple func_tuple;
Form_pg_proc functup;
char *fn_name;
int syntaxerrposition;
/* Need access to function's pg_proc tuple */
func_tuple = SearchSysCache(PROCOID,
ObjectIdGetDatum(flinfo->fn_oid),
0, 0, 0);
if (!HeapTupleIsValid(func_tuple))
return; /* shouldn't happen */
functup = (Form_pg_proc) GETSTRUCT(func_tuple);
fn_name = NameStr(functup->proname);
/*
* If there is a syntax error position, convert to internal syntax error
*/
syntaxerrposition = geterrposition();
if (syntaxerrposition > 0)
{
bool isnull;
Datum tmp;
char *prosrc;
tmp = SysCacheGetAttr(PROCOID, func_tuple, Anum_pg_proc_prosrc,
&isnull);
if (isnull)
elog(ERROR, "null prosrc");
prosrc = TextDatumGetCString(tmp);
errposition(0);
internalerrposition(syntaxerrposition);
internalerrquery(prosrc);
pfree(prosrc);
}
/*
* Try to determine where in the function we failed. If there is a query * with non-null QueryDesc, finger it. (We check this rather than looking
* for F_EXEC_RUN state, so that errors during ExecutorStart or
* ExecutorEnd are blamed on the appropriate query; see postquel_start and
* postquel_end.)
*/
if (fcache)
{
execution_state *es;
int query_num;
es = fcache->func_state;
query_num = 1;
while (es)
{
if (es->qd)
{
errcontext("SQL function \"%s\" statement %d",
fn_name, query_num);
break;
}
es = es->next;
query_num++;
}
if (es == NULL)
{
/*
* couldn't identify a running query; might be function entry,
* function exit, or between queries.
*/
errcontext("SQL function \"%s\"", fn_name);
}
}
else
{
/* must have failed during init_sql_fcache() */
errcontext("SQL function \"%s\" during startup", fn_name);
}
ReleaseSysCache(func_tuple);
}
/*
* callback function in case a function-returning-set needs to be shut down
* before it has been run to completion
*/
static void
ShutdownSQLFunction(Datum arg)
{
SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) DatumGetPointer(arg);
execution_state *es = fcache->func_state;
while (es != NULL)
{
/* Shut down anything still running */
if (es->status == F_EXEC_RUN)
postquel_end(es);
/* Reset states to START in case we're called again */
es->status = F_EXEC_START;
es = es->next;
}
/* Release tuplestore if we have one */
if (fcache->tstore)
tuplestore_end(fcache->tstore);
fcache->tstore = NULL;
/* execUtils will deregister the callback... */
fcache->shutdown_reg = false;
}
/*
* check_sql_fn_retval() -- check return value of a list of sql parse trees.
*
* The return value of a sql function is the value returned by the last
* canSetTag query in the function. We do some ad-hoc type checking here
* to be sure that the user is returning the type he claims. There are
* also a couple of strange-looking features to assist callers in dealing
* with allowed special cases, such as binary-compatible result types.
*
* For a polymorphic function the passed rettype must be the actual resolved
* output type of the function; we should never see a polymorphic pseudotype
* such as ANYELEMENT as rettype. (This means we can't check the type during
* function definition of a polymorphic function.)
*
* This function returns true if the sql function returns the entire tuple
* result of its final statement, and false otherwise. Note that because we
* allow "SELECT rowtype_expression", this may be false even when the declared
* function return type is a rowtype.
*
* If insertRelabels is true, then binary-compatible cases are dealt with
* by actually inserting RelabelType nodes into the output targetlist;
* obviously the caller must pass a parsetree that it's okay to modify in this
* case.
*
* If junkFilter isn't NULL, then *junkFilter is set to a JunkFilter defined
* to convert the function's tuple result to the correct output tuple type.
* Exception: if the function is defined to return VOID then *junkFilter is
* set to NULL.
*/
bool
check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
bool insertRelabels,
JunkFilter **junkFilter)
{
Query *parse;
List *tlist;
int tlistlen;
char fn_typtype;
Oid restype;
ListCell *lc;
AssertArg(!IsPolymorphicType(rettype));
if (junkFilter)
*junkFilter = NULL; /* initialize in case of VOID result */
/*
* Find the last canSetTag query in the list. This isn't necessarily
* the last parsetree, because rule rewriting can insert queries after
* what the user wrote.
*/
parse = NULL;
foreach(lc, queryTreeList)
{
Query *q = (Query *) lfirst(lc);
if (q->canSetTag)
parse = q;
}
/*
* If it's a plain SELECT, it returns whatever the targetlist says.
* Otherwise, if it's INSERT/UPDATE/DELETE with RETURNING, it returns that.
* Otherwise, the function return type must be VOID.
*
* Note: eventually replace this test with QueryReturnsTuples? We'd need
* a more general method of determining the output type, though. Also,
* it seems too dangerous to consider FETCH or EXECUTE as returning a * determinable rowtype, since they depend on relatively short-lived
* entities.
*/
if (parse &&
parse->commandType == CMD_SELECT &&
parse->utilityStmt == NULL &&
parse->intoClause == NULL)
{
tlist = parse->targetList;
}
else if (parse &&
(parse->commandType == CMD_INSERT ||
parse->commandType == CMD_UPDATE ||
parse->commandType == CMD_DELETE) &&
parse->returningList)
{
tlist = parse->returningList;
}
else
{
/* Empty function body, or last statement is a utility command */
if (rettype != VOIDOID)
ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("return type mismatch in function declared to return %s",
format_type_be(rettype)),
errdetail("Function's final statement must be SELECT or INSERT/UPDATE/DELETE RETURNING.")));
return false;
}
/*
* OK, check that the targetlist returns something matching the declared
* type. (We used to insist that the declared type not be VOID in this
* case, but that makes it hard to write a void function that exits after
* calling another void function. Instead, we insist that the tlist
* return void ... so void is treated as if it were a scalar type below.)
*/
/*
* Count the non-junk entries in the result targetlist.
*/
tlistlen = ExecCleanTargetListLength(tlist);
fn_typtype = get_typtype(rettype);
if (fn_typtype == TYPTYPE_BASE ||
fn_typtype == TYPTYPE_DOMAIN ||
fn_typtype == TYPTYPE_ENUM ||
rettype == VOIDOID)
{
/*
* For scalar-type returns, the target list must have exactly one
* non-junk entry, and its type must agree with what the user
* declared; except we allow binary-compatible types too.
*/
TargetEntry *tle;
if (tlistlen != 1)
ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("return type mismatch in function declared to return %s",
format_type_be(rettype)),
errdetail("Final statement must return exactly one column.")));
/* We assume here that non-junk TLEs must come first in tlists */
tle = (TargetEntry *) linitial(tlist);
Assert(!tle->resjunk);
restype = exprType((Node *) tle->expr);
if (!IsBinaryCoercible(restype, rettype)) ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("return type mismatch in function declared to return %s",
format_type_be(rettype)),
errdetail("Actual return type is %s.",
format_type_be(restype))));
if (insertRelabels && restype != rettype)
tle->expr = (Expr *) makeRelabelType(tle->expr,
rettype,
-1,
COERCE_DONTCARE);
/* Set up junk filter if needed */
if (junkFilter)
*junkFilter = ExecInitJunkFilter(tlist, false, NULL);
}
else if (fn_typtype == TYPTYPE_COMPOSITE || rettype == RECORDOID)
{
/* Returns a rowtype */
TupleDesc tupdesc;
int tupnatts; /* physical number of columns in tuple */
int tuplogcols; /* # of nondeleted columns in tuple */
int colindex; /* physical column index */
/*
* If the target list is of length 1, and the type of the varnode in
* the target list matches the declared return type, this is okay.
* This can happen, for example, where the body of the function is
* 'SELECT func2()', where func2 has the same composite return type
* as the function that's calling it.
*/
if (tlistlen == 1)
{
TargetEntry *tle = (TargetEntry *) linitial(tlist);
Assert(!tle->resjunk);
restype = exprType((Node *) tle->expr);
if (IsBinaryCoercible(restype, rettype))
{
if (insertRelabels && restype != rettype)
tle->expr = (Expr *) makeRelabelType(tle->expr,
rettype,
-1,
COERCE_DONTCARE);
/* Set up junk filter if needed */
if (junkFilter)
*junkFilter = ExecInitJunkFilter(tlist, false, NULL);
return false; /* NOT returning whole tuple */
}
}
/* Is the rowtype fixed, or determined only at runtime? */
if (get_func_result_type(func_id, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
{
/*
* Assume we are returning the whole tuple. Crosschecking against
* what the caller expects will happen at runtime.
*/
if (junkFilter)
*junkFilter = ExecInitJunkFilter(tlist, false, NULL);
return true;
}
Assert(tupdesc);
/*
* Verify that the targetlist matches the return tuple type. We scan
* the non-deleted attributes to ensure that they match the datatypes
* of the non-resjunk columns.
*/
tupnatts = tupdesc->natts; tuplogcols = 0; /* we'll count nondeleted cols as we go */
colindex = 0;
foreach(lc, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(lc);
Form_pg_attribute attr;
Oid tletype;
Oid atttype;
if (tle->resjunk)
continue;
do
{
colindex++;
if (colindex > tupnatts)
ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("return type mismatch in function declared to return %s",
format_type_be(rettype)),
errdetail("Final statement returns too many columns.")));
attr = tupdesc->attrs[colindex - 1];
} while (attr->attisdropped);
tuplogcols++;
tletype = exprType((Node *) tle->expr);
atttype = attr->atttypid;
if (!IsBinaryCoercible(tletype, atttype))
ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("return type mismatch in function declared to return %s",
format_type_be(rettype)),
errdetail("Final statement returns %s instead of %s at column %d.",
format_type_be(tletype),
format_type_be(atttype),
tuplogcols)));
if (insertRelabels && tletype != atttype)
tle->expr = (Expr *) makeRelabelType(tle->expr,
atttype,
-1,
COERCE_DONTCARE);
}
for (;;)
{
colindex++;
if (colindex > tupnatts)
break;
if (!tupdesc->attrs[colindex - 1]->attisdropped)
tuplogcols++;
}
if (tlistlen != tuplogcols)
ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("return type mismatch in function declared to return %s",
format_type_be(rettype)),
errdetail("Final statement returns too few columns.")));
/* Set up junk filter if needed */
if (junkFilter)
*junkFilter = ExecInitJunkFilterConversion(tlist,
CreateTupleDescCopy(tupdesc),
NULL);
/* Report that we are returning entire tuple result */
return true;
}
else ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("return type %s is not supported for SQL functions",
format_type_be(rettype))));
return false;
}
/*
* CreateSQLFunctionDestReceiver -- create a suitable DestReceiver object
*
* Since CreateDestReceiver doesn't accept the parameters we'd need,
* we just leave the private fields zeroed here. postquel_start will
* fill them in.
*/
DestReceiver *
CreateSQLFunctionDestReceiver(void)
{
DR_sqlfunction *self = (DR_sqlfunction *) palloc0(sizeof(DR_sqlfunction));
self->pub.receiveSlot = sqlfunction_receive;
self->pub.rStartup = sqlfunction_startup;
self->pub.rShutdown = sqlfunction_shutdown;
self->pub.rDestroy = sqlfunction_destroy;
self->pub.mydest = DestSQLFunction;
return (DestReceiver *) self;
}
/*
* sqlfunction_startup --- executor startup
*/
static void
sqlfunction_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
{
/* no-op */
}
/*
* sqlfunction_receive --- receive one tuple
*/
static void
sqlfunction_receive(TupleTableSlot *slot, DestReceiver *self)
{
DR_sqlfunction *myState = (DR_sqlfunction *) self;
MemoryContext oldcxt;
/* Filter tuple as needed */
slot = ExecFilterJunk(myState->filter, slot);
/* Store the filtered tuple into the tuplestore */
oldcxt = MemoryContextSwitchTo(myState->cxt);
tuplestore_puttupleslot(myState->tstore, slot);
MemoryContextSwitchTo(oldcxt);
}
/*
* sqlfunction_shutdown --- executor end
*/
static void
sqlfunction_shutdown(DestReceiver *self)
{
/* no-op */
}
/*
* sqlfunction_destroy --- release DestReceiver object
*/
static voidsqlfunction_destroy(DestReceiver *self)
{
pfree(self);
}