greenplumn functions 源码
greenplumn functions 代码
文件路径：/src/backend/executor/functions.c
/*-------------------------------------------------------------------------
*
* functions.c
* Execution of SQL-language functions
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/executor/functions.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/htup_details.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "executor/executor.h" /* ExecutorStart, ExecutorRun, etc */
#include "executor/functions.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "parser/parse_coerce.h"
#include "parser/parse_func.h"
#include "storage/proc.h"
#include "tcop/utility.h"
#include "utils/builtins.h"
#include "utils/datum.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
#include "utils/typcache.h"
#include "utils/metrics_utils.h"
#include "catalog/namespace.h"
#include "catalog/pg_namespace.h"
#include "cdb/cdbvars.h"
#include "optimizer/clauses.h"
#include "executor/spi.h"
#include "cdb/memquota.h"
#include "postmaster/autostats.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.
*
* The "next" fields chain together all the execution_state records generated
* from a single original parsetree. (There will only be more than one in
* case of rule expansion of the original parsetree.)
*/
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 */
PlannedStmt *stmt; /* plan for this query */
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 should rewrite this code to use plancache.c to save parse/plan
* results for longer than that.
*
* Physically, though, the data has the lifespan of the FmgrInfo that's used
* to call the function, and there are cases (particularly with indexes)
* where the FmgrInfo might survive across transactions. We cannot assume
* that the parse/plan trees are good for longer than the (sub)transaction in
* which parsing was done, so we must mark the record with the LXID/subxid of
* its creation time, and regenerate everything if that's obsolete. To avoid
* memory leakage when we do have to regenerate things, all the data is kept
* in a sub-context of the FmgrInfo's fn_mcxt.
*/
typedef struct
{
char *fname; /* function name (for error msgs) */
char *src; /* function body text (for error msgs) */
SQLFunctionParseInfoPtr pinfo; /* data for parser callback hooks */
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 */
/*
* func_state is a List of execution_state records, each of which is the
* first for its original parsetree, with any additional records chained
* to it via the "next" fields. This sublist structure is needed to keep
* track of where the original query boundaries are.
*/
List *func_state;
MemoryContext fcontext; /* memory context holding this struct and all
* subsidiary data */
LocalTransactionId lxid; /* lxid in which cache was made */
SubTransactionId subxid; /* subxid in which cache was made */
} SQLFunctionCache;
typedef SQLFunctionCache *SQLFunctionCachePtr;
/*
* Data structure needed by the parser callback hooks to resolve parameter
* references during parsing of a SQL function's body. This is separate from
* SQLFunctionCache since we sometimes do parsing separately from execution.
*/
typedef struct SQLFunctionParseInfo
{
char *fname; /* function's name */
int nargs; /* number of input arguments */
Oid *argtypes; /* resolved types of input arguments */
char **argnames; /* names of input arguments; NULL if none */
/* Note that argnames[i] can be NULL, if some args are unnamed */
Oid collation; /* function's input collation, if known */
} SQLFunctionParseInfo;
/* non-export function prototypes */
static Node *sql_fn_param_ref(ParseState *pstate, ParamRef *pref);
static Node *sql_fn_post_column_ref(ParseState *pstate,
ColumnRef *cref, Node *var);
static Node *sql_fn_make_param(SQLFunctionParseInfoPtr pinfo,
int paramno, int location);
static Node *sql_fn_resolve_param_name(SQLFunctionParseInfoPtr pinfo,
const char *paramname, int location);
static List *init_execution_state(List *queryTree_list,
SQLFunctionCachePtr fcache,
bool lazyEvalOK);
static void init_sql_fcache(FmgrInfo *finfo, Oid collation, 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 bool querytree_safe_for_qe_walker(Node *expr, void *context);
static void sqlfunction_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
static bool sqlfunction_receive(TupleTableSlot *slot, DestReceiver *self);
static void sqlfunction_shutdown(DestReceiver *self);
static void sqlfunction_destroy(DestReceiver *self);
static bool
querytree_safe_for_qe_walker(Node *expr, void *context)
{
Assert(context == NULL);
if (!expr)
{
/**
* Do not end recursion just because we have reached one leaf node.
*/
return false;
}
switch(nodeTag(expr))
{
case T_Query:
{
Query *q = (Query *) expr;
if (!allow_segment_DML &&
(q->commandType != CMD_SELECT
|| (q->utilityStmt != NULL &&
IsA(q->utilityStmt, CreateTableAsStmt))
|| q->resultRelation > 0))
{
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("function cannot execute on a QE slice because it issues a non-SELECT statement")));
}
ListCell * f = NULL;
foreach(f,q->rtable)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(f);
if (rte->rtekind == RTE_RELATION)
{
Assert(rte->relid != InvalidOid);
Oid namespaceId = get_rel_namespace(rte->relid);
Assert(namespaceId != InvalidOid);
if (!(IsCatalogNamespace(namespaceId) ||
IsToastNamespace(namespaceId) ||
IsAoSegmentNamespace(namespaceId) ||
IsReplicatedTable(rte->relid)))
{
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("function cannot execute on a QE slice because it accesses relation \"%s.%s\"",
quote_identifier(get_namespace_name(namespaceId)),
quote_identifier(get_rel_name(rte->relid)))));
}
}
}
query_tree_walker(q, querytree_safe_for_qe_walker, context, 0);
break;
}
default:
break;
}
return expression_tree_walker(expr, querytree_safe_for_qe_walker, context);
}
/**
* This function determines if the query tree is safe to be planned and
* executed on a QE. The checks it performs are:
* 1. The query cannot access any non-catalog relation except it's a replicated table.
* 2. The query must be select only.
* In case of a problem, the method spits out an error.
*/
void
querytree_safe_for_qe(Node *node)
{
Assert(node);
querytree_safe_for_qe_walker(node, NULL);
}
/*
* Prepare the SQLFunctionParseInfo struct for parsing a SQL function body
*
* This includes resolving actual types of polymorphic arguments.
*
* call_expr can be passed as NULL, but then we will fail if there are any
* polymorphic arguments.
*/
SQLFunctionParseInfoPtr
prepare_sql_fn_parse_info(HeapTuple procedureTuple,
Node *call_expr,
Oid inputCollation)
{
SQLFunctionParseInfoPtr pinfo;
Form_pg_proc procedureStruct = (Form_pg_proc) GETSTRUCT(procedureTuple);
int nargs;
pinfo = (SQLFunctionParseInfoPtr) palloc0(sizeof(SQLFunctionParseInfo));
/* Function's name (only) can be used to qualify argument names */
pinfo->fname = pstrdup(NameStr(procedureStruct->proname));
/* Save the function's input collation */
pinfo->collation = inputCollation;
/*
* Copy input argument types from the pg_proc entry, then resolve any
* polymorphic types.
*/
pinfo->nargs = nargs = procedureStruct->pronargs;
if (nargs > 0)
{
Oid *argOidVect;
int argnum;
argOidVect = (Oid *) palloc(nargs * sizeof(Oid));
memcpy(argOidVect,
procedureStruct->proargtypes.values,
nargs * sizeof(Oid));
for (argnum = 0; argnum < nargs; argnum++)
{
Oid argtype = argOidVect[argnum];
if (IsPolymorphicType(argtype))
{
argtype = get_call_expr_argtype(call_expr, 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;
}
}
pinfo->argtypes = argOidVect;
}
/*
* Collect names of arguments, too, if any
*/
if (nargs > 0)
{
Datum proargnames;
Datum proargmodes;
int n_arg_names;
bool isNull;
proargnames = SysCacheGetAttr(PROCNAMEARGSNSP, procedureTuple,
Anum_pg_proc_proargnames,
&isNull);
if (isNull)
proargnames = PointerGetDatum(NULL); /* just to be sure */
proargmodes = SysCacheGetAttr(PROCNAMEARGSNSP, procedureTuple,
Anum_pg_proc_proargmodes,
&isNull);
if (isNull)
proargmodes = PointerGetDatum(NULL); /* just to be sure */
n_arg_names = get_func_input_arg_names(proargnames, proargmodes,
&pinfo->argnames);
/* Paranoia: ignore the result if too few array entries */
if (n_arg_names < nargs)
pinfo->argnames = NULL;
}
else
pinfo->argnames = NULL;
return pinfo;
}
/*
* Parser setup hook for parsing a SQL function body.
*/
void
sql_fn_parser_setup(struct ParseState *pstate, SQLFunctionParseInfoPtr pinfo)
{
pstate->p_pre_columnref_hook = NULL;
pstate->p_post_columnref_hook = sql_fn_post_column_ref;
pstate->p_paramref_hook = sql_fn_param_ref;
/* no need to use p_coerce_param_hook */
pstate->p_ref_hook_state = (void *) pinfo;
}
/*
* sql_fn_post_column_ref parser callback for ColumnRefs
*/
static Node *
sql_fn_post_column_ref(ParseState *pstate, ColumnRef *cref, Node *var)
{
SQLFunctionParseInfoPtr pinfo = (SQLFunctionParseInfoPtr) pstate->p_ref_hook_state;
int nnames;
Node *field1;
Node *subfield = NULL;
const char *name1;
const char *name2 = NULL;
Node *param;
/*
* Never override a table-column reference. This corresponds to
* considering the parameter names to appear in a scope outside the
* individual SQL commands, which is what we want.
*/
if (var != NULL)
return NULL;
/*----------
* The allowed syntaxes are:
*
* A A = parameter name
* A.B A = function name, B = parameter name
* OR: A = record-typed parameter name, B = field name
* (the first possibility takes precedence)
* A.B.C A = function name, B = record-typed parameter name,
* C = field name
* A.* Whole-row reference to composite parameter A.
* A.B.* Same, with A = function name, B = parameter name
*
* Here, it's sufficient to ignore the "*" in the last two cases --- the
* main parser will take care of expanding the whole-row reference.
*----------
*/
nnames = list_length(cref->fields);
if (nnames > 3)
return NULL;
if (IsA(llast(cref->fields), A_Star))
nnames--;
field1 = (Node *) linitial(cref->fields);
Assert(IsA(field1, String));
name1 = strVal(field1);
if (nnames > 1)
{
subfield = (Node *) lsecond(cref->fields);
Assert(IsA(subfield, String));
name2 = strVal(subfield);
}
if (nnames == 3)
{
/*
* Three-part name: if the first part doesn't match the function name,
* we can fail immediately. Otherwise, look up the second part, and
* take the third part to be a field reference.
*/
if (strcmp(name1, pinfo->fname) != 0)
return NULL;
param = sql_fn_resolve_param_name(pinfo, name2, cref->location);
subfield = (Node *) lthird(cref->fields);
Assert(IsA(subfield, String));
}
else if (nnames == 2 && strcmp(name1, pinfo->fname) == 0)
{
/*
* Two-part name with first part matching function name: first see if
* second part matches any parameter name.
*/
param = sql_fn_resolve_param_name(pinfo, name2, cref->location);
if (param)
{
/* Yes, so this is a parameter reference, no subfield */
subfield = NULL;
}
else
{
/* No, so try to match as parameter name and subfield */
param = sql_fn_resolve_param_name(pinfo, name1, cref->location);
}
}
else
{
/* Single name, or parameter name followed by subfield */
param = sql_fn_resolve_param_name(pinfo, name1, cref->location);
}
if (!param)
return NULL; /* No match */
if (subfield)
{
/*
* Must be a reference to a field of a composite parameter; otherwise
* ParseFuncOrColumn will return NULL, and we'll fail back at the
* caller.
*/
param = ParseFuncOrColumn(pstate,
list_make1(subfield),
list_make1(param),
pstate->p_last_srf,
NULL,
false,
cref->location);
}
return param;
}
/*
* sql_fn_param_ref parser callback for ParamRefs ($n symbols)
*/
static Node *
sql_fn_param_ref(ParseState *pstate, ParamRef *pref)
{
SQLFunctionParseInfoPtr pinfo = (SQLFunctionParseInfoPtr) pstate->p_ref_hook_state;
int paramno = pref->number;
/* Check parameter number is valid */
if (paramno <= 0 || paramno > pinfo->nargs)
return NULL; /* unknown parameter number */
return sql_fn_make_param(pinfo, paramno, pref->location);
}
/*
* sql_fn_make_param construct a Param node for the given paramno
*/
static Node *
sql_fn_make_param(SQLFunctionParseInfoPtr pinfo,
int paramno, int location)
{
Param *param;
param = makeNode(Param);
param->paramkind = PARAM_EXTERN;
param->paramid = paramno;
param->paramtype = pinfo->argtypes[paramno - 1];
param->paramtypmod = -1;
param->paramcollid = get_typcollation(param->paramtype);
param->location = location;
/*
* If we have a function input collation, allow it to override the
* type-derived collation for parameter symbols. (XXX perhaps this should
* not happen if the type collation is not default?)
*/
if (OidIsValid(pinfo->collation) && OidIsValid(param->paramcollid))
param->paramcollid = pinfo->collation;
return (Node *) param;
}
/*
* Search for a function parameter of the given name; if there is one,
* construct and return a Param node for it. If not, return NULL.
* Helper function for sql_fn_post_column_ref.
*/
static Node *
sql_fn_resolve_param_name(SQLFunctionParseInfoPtr pinfo,
const char *paramname, int location)
{
int i;
if (pinfo->argnames == NULL)
return NULL;
for (i = 0; i < pinfo->nargs; i++)
{
if (pinfo->argnames[i] && strcmp(pinfo->argnames[i], paramname) == 0)
return sql_fn_make_param(pinfo, i + 1, location);
}
return NULL;
}
/*
* Set up the per-query execution_state records for a SQL function.
*
* The input is a List of Lists of parsed and rewritten, but not planned,
* querytrees. The sublist structure denotes the original query boundaries.
*/
static List *
init_execution_state(List *queryTree_list,
SQLFunctionCachePtr fcache,
bool lazyEvalOK)
{
List *eslist = NIL;
execution_state *lasttages = NULL;
ListCell *lc1;
foreach(lc1, queryTree_list)
{
List *qtlist = lfirst_node(List, lc1);
execution_state *firstes = NULL;
execution_state *preves = NULL;
ListCell *lc2;
foreach(lc2, qtlist)
{
Query *queryTree = lfirst_node(Query, lc2);
PlannedStmt *stmt;
execution_state *newes;
/* Plan the query if needed */
if (queryTree->commandType == CMD_UTILITY)
{
/* Utility commands require no planning. */
stmt = makeNode(PlannedStmt);
stmt->commandType = CMD_UTILITY;
stmt->canSetTag = queryTree->canSetTag;
stmt->utilityStmt = queryTree->utilityStmt;
stmt->stmt_location = queryTree->stmt_location;
stmt->stmt_len = queryTree->stmt_len;
}
else
stmt = pg_plan_query(queryTree,
CURSOR_OPT_PARALLEL_OK,
NULL);
if (IsA(stmt, PlannedStmt))
((PlannedStmt*)stmt)->metricsQueryType = FUNCTION_INNER_QUERY;
/*
* Precheck all commands for validity in a function. This should
* generally match the restrictions spi.c applies.
*/
if (stmt->commandType == CMD_UTILITY)
{
if (IsA(stmt->utilityStmt, CopyStmt) &&
((CopyStmt *) stmt->utilityStmt)->filename == NULL)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot COPY to/from client in a SQL function")));
if (IsA(stmt->utilityStmt, 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->utilityStmt))));
}
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((Node *) stmt))));
if (IsInParallelMode() && !CommandIsReadOnly(stmt))
PreventCommandIfParallelMode(CreateCommandTag((Node *) stmt));
/* OK, build the execution_state for this query */
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;
}
eslist = lappend(eslist, firstes);
}
/*
* 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 the last statement in such a function.
*/
if (lasttages && fcache->junkFilter)
{
lasttages->setsResult = true;
if (lazyEvalOK &&
lasttages->stmt->commandType == CMD_SELECT &&
!lasttages->stmt->hasModifyingCTE)
fcache->lazyEval = lasttages->lazyEval = true;
}
return eslist;
}
/*
* Initialize the SQLFunctionCache for a SQL function
*/
static void
init_sql_fcache(FmgrInfo *finfo, Oid collation, bool lazyEvalOK)
{
Oid foid = finfo->fn_oid;
MemoryContext fcontext;
MemoryContext oldcontext;
Oid rettype;
HeapTuple procedureTuple;
Form_pg_proc procedureStruct;
SQLFunctionCachePtr fcache;
List *raw_parsetree_list;
List *queryTree_list;
List *flat_query_list;
ListCell *lc;
Datum tmp;
bool isNull;
/*
* Create memory context that holds all the SQLFunctionCache data. It
* must be a child of whatever context holds the FmgrInfo.
*/
fcontext = AllocSetContextCreate(finfo->fn_mcxt,
"SQL function",
ALLOCSET_DEFAULT_SIZES);
oldcontext = MemoryContextSwitchTo(fcontext);
/*
* Create the struct proper, link it to fcontext and fn_extra. Once this
* is done, we'll be able to recover the memory after failure, even if the
* FmgrInfo is long-lived.
*/
fcache = (SQLFunctionCachePtr) palloc0(sizeof(SQLFunctionCache));
fcache->fcontext = fcontext;
finfo->fn_extra = (void *) fcache;
/*
* get the procedure tuple corresponding to the given function Oid
*/
procedureTuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(foid));
if (!HeapTupleIsValid(procedureTuple))
elog(ERROR, "cache lookup failed for function %u", foid);
procedureStruct = (Form_pg_proc) GETSTRUCT(procedureTuple);
/*
* copy function name immediately for use by error reporting callback, and
* for use as memory context identifier
*/
fcache->fname = pstrdup(NameStr(procedureStruct->proname));
MemoryContextSetIdentifier(fcontext, fcache->fname);
/*
* 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. Also make
* sure that parameter symbols are considered to have the function's
* resolved input collation.
*/
fcache->pinfo = prepare_sql_fn_parse_info(procedureTuple,
finfo->fn_expr,
collation);
/*
* 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. Use sublists to
* keep track of the original query boundaries. But we also build a
* "flat" list of the rewritten queries to pass to check_sql_fn_retval.
* This is because the last canSetTag query determines the result type
* independently of query boundaries --- and it might not be in the last
* sublist, for example if the last query rewrites to DO INSTEAD NOTHING.
* (It might not be unreasonable to throw an error in such a case, but
* this is the historical behavior and it doesn't seem worth changing.)
*
* Note: since parsing and planning is done in fcontext, we will generate
* a lot of cruft that lives as long as the fcache does. This is annoying
* but we'll not worry about it until the module is rewritten to use
* plancache.c.
*/
raw_parsetree_list = pg_parse_query(fcache->src);
queryTree_list = NIL;
flat_query_list = NIL;
foreach(lc, raw_parsetree_list)
{
RawStmt *parsetree = lfirst_node(RawStmt, lc);
List *queryTree_sublist;
queryTree_sublist = pg_analyze_and_rewrite_params(parsetree,
fcache->src,
(ParserSetupHook) sql_fn_parser_setup,
fcache->pinfo,
NULL);
queryTree_list = lappend(queryTree_list, queryTree_sublist);
flat_query_list = list_concat(flat_query_list,
list_copy(queryTree_sublist));
}
check_sql_fn_statements(flat_query_list);
/*
* If we have only SELECT statements with no FROM clauses, we should
* be able to execute them locally, even on the QE. Most often, this is something
* like SELECT $1
* Functions use that type of SELECT to evaluate expressions, so without those,
* no functions would be useful.
*
* We also need to execute certain catalog queries locally. The
* Fault-Tolerance system does queries of gp_segment_configuration, and
* some DDL and Utility commands do selects from the catalog table, etc.
* So, if the FROM clause consists only of catalog tables, we will run the
* query locally.
*
*/
if (Gp_role == GP_ROLE_EXECUTE)
{
/* This will error out if there is a problem with the query tree */
querytree_safe_for_qe((Node *) queryTree_list);
}
/*
* 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,
flat_query_list,
NULL,
&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);
/* Mark fcache with time of creation to show it's valid */
fcache->lxid = MyProc->lxid;
fcache->subxid = GetCurrentSubTransactionId();
ReleaseSysCache(procedureTuple);
MemoryContextSwitchTo(oldcontext);
}
/* Start up execution of one execution_state node */
static void
postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
{
DestReceiver *dest;
Assert(es->qd == NULL);
/* Caller should have ensured a suitable snapshot is active */
Assert(ActiveSnapshotSet());
/*
* 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);
/* 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;
es->qd = CreateQueryDesc(es->stmt,
fcache->src,
GetActiveSnapshot(),
InvalidSnapshot,
dest,
fcache->paramLI,
es->qd ? es->qd->queryEnv : NULL,
0);
/* GPDB hook for collecting query info */
if (query_info_collect_hook)
(*query_info_collect_hook)(METRICS_QUERY_SUBMIT, es->qd);
/* Utility commands don't need Executor. */
if (es->qd->operation != CMD_UTILITY)
{
int eflags;
if (!IsResManagerMemoryPolicyNone()
&& SPI_IsMemoryReserved())
{
es->qd->plannedstmt->query_mem = SPI_GetMemoryReservation();
}
/*
* In lazyEval mode, do not let the executor set up an AfterTrigger
* context. This is necessary not just an optimization, because we
* mustn't exit from the function execution with a stacked
* AfterTrigger level still active. We are careful not to select
* lazyEval mode for any statement that could possibly queue triggers.
*/
if (es->lazyEval)
eflags = EXEC_FLAG_SKIP_TRIGGERS;
else
eflags = 0; /* default run-to-completion flags */
ExecutorStart(es->qd, eflags);
}
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;
if (es->qd->operation == CMD_UTILITY)
{
ProcessUtility(es->qd->plannedstmt,
fcache->src,
PROCESS_UTILITY_QUERY,
es->qd->params,
es->qd->queryEnv,
es->qd->dest,
NULL);
result = true; /* never stops early */
}
else
{
/* Run regular commands to completion unless lazyEval */
uint64 count = (es->lazyEval) ? 1 : 0;
ExecutorRun(es->qd, ForwardScanDirection, count, !fcache->returnsSet || !es->lazyEval);
/*
* If we requested run to completion OR there was no tuple returned,
* command must be complete.
*/
result = (count == 0 || es->qd->estate->es_processed == 0);
}
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->operation != CMD_UTILITY)
{
Oid relationOid = InvalidOid; /* relation that is modified */
AutoStatsCmdType cmdType = AUTOSTATS_CMDTYPE_SENTINEL; /* command type */
if (Gp_role == GP_ROLE_DISPATCH)
autostats_get_cmdtype(es->qd, &cmdType, &relationOid);
ExecutorFinish(es->qd);
ExecutorEnd(es->qd);
/* MPP-14001: Running auto_stats */
if (Gp_role == GP_ROLE_DISPATCH)
auto_stats(cmdType, relationOid, es->qd->es_processed, true /* inFunction */);
}
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;
if (fcache->paramLI == NULL)
{
paramLI = makeParamList(nargs);
fcache->paramLI = paramLI;
}
else
{
paramLI = fcache->paramLI;
Assert(paramLI->numParams == nargs);
}
for (int i = 0; i < nargs; i++)
{
ParamExternData *prm = ¶mLI->params[i];
prm->value = fcinfo->args[i].value;
prm->isnull = fcinfo->args[i].isnull;
prm->pflags = 0;
prm->ptype = fcache->pinfo->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 = ExecFetchSlotHeapTupleDatum(slot);
}
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)
{
SQLFunctionCachePtr fcache;
ErrorContextCallback sqlerrcontext;
MemoryContext oldcontext;
bool randomAccess;
bool lazyEvalOK;
bool is_first;
bool pushed_snapshot;
execution_state *es;
TupleTableSlot *slot;
Datum result;
List *eslist;
ListCell *eslc;
/*
* 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. But
* note we do not require caller to provide an expectedDesc.
*/
if (!rsi || !IsA(rsi, ReturnSetInfo) ||
(rsi->allowedModes & SFRM_ValuePerCall) == 0 ||
(rsi->allowedModes & SFRM_Materialize) == 0)
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; or re-initialize
* if the cache is stale.
*/
fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
if (fcache != NULL)
{
if (fcache->lxid != MyProc->lxid ||
!SubTransactionIsActive(fcache->subxid))
{
/* It's stale; unlink and delete */
fcinfo->flinfo->fn_extra = NULL;
MemoryContextDelete(fcache->fcontext);
fcache = NULL;
}
}
if (fcache == NULL)
{
init_sql_fcache(fcinfo->flinfo, PG_GET_COLLATION(), lazyEvalOK);
fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
}
/*
* Switch to context in which the fcache lives. This ensures that our
* tuplestore etc will have sufficient lifetime. The sub-executor is
* responsible for deleting per-tuple information. (XXX in the case of a
* long-lived FmgrInfo, this policy represents more memory leakage, but
* it's not entirely clear where to keep stuff instead.)
*/
oldcontext = MemoryContextSwitchTo(fcache->fcontext);
/*
* Find first unfinished query in function, and note whether it's the
* first query.
*/
eslist = fcache->func_state;
es = NULL;
is_first = true;
foreach(eslc, eslist)
{
es = (execution_state *) lfirst(eslc);
while (es && es->status == F_EXEC_DONE)
{
is_first = false;
es = es->next;
}
if (es)
break;
}
/*
* Convert params to appropriate format if starting a fresh execution. (If
* continuing execution, we can re-use prior params.)
*/
if (is_first && 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);
PG_TRY();
{
/*
* 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.
*
* Notes about snapshot management:
*
* In a read-only function, we just use the surrounding query's snapshot.
*
* In a non-read-only function, we rely on the fact that we'll never
* suspend execution between queries of the function: the only reason to
* suspend execution before completion is if we are returning a row from a
* lazily-evaluated SELECT. So, when first entering this loop, we'll
* either start a new query (and push a fresh snapshot) or re-establish
* the active snapshot from the existing query descriptor. If we need to
* start a new query in a subsequent execution of the loop, either we need
* a fresh snapshot (and pushed_snapshot is false) or the existing
* snapshot is on the active stack and we can just bump its command ID.
*/
pushed_snapshot = false;
while (es)
{
bool completed;
if (es->status == F_EXEC_START)
{
/*
* If not read-only, be sure to advance the command counter for
* each command, so that all work to date in this transaction is
* visible. Take a new snapshot if we don't have one yet,
* otherwise just bump the command ID in the existing snapshot.
*/
if (!fcache->readonly_func)
{
CommandCounterIncrement();
if (!pushed_snapshot)
{
PushActiveSnapshot(GetTransactionSnapshot());
pushed_snapshot = true;
}
else
UpdateActiveSnapshotCommandId();
}
postquel_start(es, fcache);
}
else if (!fcache->readonly_func && !pushed_snapshot)
{
/* Re-establish active snapshot when re-entering function */
PushActiveSnapshot(es->qd->snapshot);
pushed_snapshot = true;
}
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;
/*
* Advance to next execution_state, which might be in the next list.
*/
es = es->next;
while (!es)
{
eslc = lnext(eslc);
if (!eslc)
break; /* end of function */
es = (execution_state *) lfirst(eslc);
/*
* Flush the current snapshot so that we will take a new one for
* the new query list. This ensures that new snaps are taken at
* original-query boundaries, matching the behavior of interactive
* execution.
*/
if (pushed_snapshot)
{
PopActiveSnapshot();
pushed_snapshot = false;
}
}
}
}
PG_CATCH();
{
PG_RE_THROW();
}
PG_END_TRY();
/*
* 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, false, 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 execSRF.c 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, false, 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 and procedures */
Assert(fcache->rettype == VOIDOID);
fcinfo->isnull = true;
result = (Datum) 0;
}
/* Clear the tuplestore, but keep it for next time */
tuplestore_clear(fcache->tstore);
}
/* Pop snapshot if we have pushed one */
if (pushed_snapshot)
PopActiveSnapshot();
/*
* 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)
{
foreach(eslc, fcache->func_state)
{
es = (execution_state *) lfirst(eslc);
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;
int syntaxerrposition;
/*
* We can do nothing useful if init_sql_fcache() didn't get as far as
* saving the function name
*/
if (fcache == NULL || fcache->fname == NULL)
return;
/*
* If there is a syntax error position, convert to internal syntax error
*/
syntaxerrposition = geterrposition();
if (syntaxerrposition > 0 && fcache->src != NULL)
{
errposition(0);
internalerrposition(syntaxerrposition);
internalerrquery(fcache->src);
}
/*
* 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->func_state)
{
execution_state *es;
int query_num;
ListCell *lc;
es = NULL;
query_num = 1;
foreach(lc, fcache->func_state)
{
es = (execution_state *) lfirst(lc);
while (es)
{
if (es->qd)
{
errcontext("SQL function \"%s\" statement %d",
fcache->fname, query_num);
break;
}
es = es->next;
}
if (es)
break;
query_num++;
}
if (es == NULL)
{
/*
* couldn't identify a running query; might be function entry,
* function exit, or between queries.
*/
errcontext("SQL function \"%s\"", fcache->fname);
}
}
else
{
/*
* Assume we failed during init_sql_fcache(). (It's possible that the
* function actually has an empty body, but in that case we may as
* well report all errors as being "during startup".)
*/
errcontext("SQL function \"%s\" during startup", fcache->fname);
}
}
/*
* 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;
ListCell *lc;
foreach(lc, fcache->func_state)
{
es = (execution_state *) lfirst(lc);
while (es)
{
/* Shut down anything still running */
if (es->status == F_EXEC_RUN)
{
/* Re-establish active snapshot for any called functions */
if (!fcache->readonly_func)
PushActiveSnapshot(es->qd->snapshot);
postquel_end(es);
if (!fcache->readonly_func)
PopActiveSnapshot();
}
/* 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_statements
*
* Check statements in an SQL function. Error out if there is anything that
* is not acceptable.
*/
void
check_sql_fn_statements(List *queryTreeList)
{
ListCell *lc;
foreach(lc, queryTreeList)
{
Query *query = lfirst_node(Query, lc);
/*
* Disallow procedures with output arguments. The current
* implementation would just throw the output values away, unless the
* statement is the last one. Per SQL standard, we should assign the
* output values by name. By disallowing this here, we preserve an
* opportunity for future improvement.
*/
if (query->commandType == CMD_UTILITY &&
IsA(query->utilityStmt, CallStmt))
{
CallStmt *stmt = castNode(CallStmt, query->utilityStmt);
HeapTuple tuple;
int numargs;
Oid *argtypes;
char **argnames;
char *argmodes;
int i;
tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(stmt->funcexpr->funcid));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for function %u", stmt->funcexpr->funcid);
numargs = get_func_arg_info(tuple, &argtypes, &argnames, &argmodes);
ReleaseSysCache(tuple);
for (i = 0; i < numargs; i++)
{
if (argmodes && (argmodes[i] == PROARGMODE_INOUT || argmodes[i] == PROARGMODE_OUT))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("calling procedures with output arguments is not supported in SQL functions")));
}
}
}
}
/*
* 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, or false if it returns just the first column
* result of that statement. It throws an error if the final statement doesn't
* return the right type at all.
*
* Note that because we allow "SELECT rowtype_expression", the result can be
* false even when the declared function return type is a rowtype.
*
* If modifyTargetList isn't NULL, the function will modify the final
* statement's targetlist in two cases:
* (1) if the tlist returns values that are binary-coercible to the expected
* type rather than being exactly the expected type. RelabelType nodes will
* be inserted to make the result types match exactly.
* (2) if there are dropped columns in the declared result rowtype. NULL
* output columns will be inserted in the tlist to match them.
* (Obviously the caller must pass a parsetree that is okay to modify when
* using this flag.) Note that this flag does not affect whether the tlist is
* considered to be a legal match to the result type, only how we react to
* allowed not-exact-match cases. *modifyTargetList will be set true iff
* we had to make any "dangerous" changes that could modify the semantics of
* the statement. If it is set true, the caller should not use the modified
* statement, but for simplicity we apply the changes anyway.
*
* 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 *modifyTargetList,
JunkFilter **junkFilter)
{
Query *parse;
List **tlist_ptr;
List *tlist;
int tlistlen;
char fn_typtype;
Oid restype;
ListCell *lc;
AssertArg(!IsPolymorphicType(rettype));
if (modifyTargetList)
*modifyTargetList = false; /* initialize for no change */
if (junkFilter)
*junkFilter = NULL; /* initialize in case of VOID result */
/*
* If it's declared to return VOID, we don't care what's in the function.
* (This takes care of the procedure case, as well.)
*/
if (rettype == VOIDOID)
return false;
/*
* 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 = lfirst_node(Query, 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)
{
tlist_ptr = &parse->targetList;
tlist = parse->targetList;
}
else if (parse &&
(parse->commandType == CMD_INSERT ||
parse->commandType == CMD_UPDATE ||
parse->commandType == CMD_DELETE) &&
parse->returningList)
{
tlist_ptr = &parse->returningList;
tlist = parse->returningList;
}
else
{
/* Empty function body, or last statement is a utility command */
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; /* keep compiler quiet */
}
/*
* OK, check that the targetlist returns something matching the declared
* type.
*/
/*
* 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 ||
fn_typtype == TYPTYPE_RANGE)
{
/*
* 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 (modifyTargetList && restype != rettype)
{
tle->expr = (Expr *) makeRelabelType(tle->expr,
rettype,
-1,
get_typcollation(rettype),
COERCE_IMPLICIT_CAST);
/* Relabel is dangerous if TLE is a sort/group or setop column */
if (tle->ressortgroupref != 0 || parse->setOperations)
*modifyTargetList = true;
}
/* Set up junk filter if needed */
if (junkFilter)
*junkFilter = ExecInitJunkFilter(tlist,
MakeSingleTupleTableSlot(NULL, &TTSOpsMinimalTuple));
}
else if (fn_typtype == TYPTYPE_COMPOSITE || rettype == RECORDOID)
{
/*
* Returns a rowtype.
*
* Note that we will not consider a domain over composite to be a
* "rowtype" return type; it goes through the scalar case above. This
* is because SQL functions don't provide any implicit casting to the
* result type, so there is no way to produce a domain-over-composite
* result except by computing it as an explicit single-column result.
*/
TupleDesc tupdesc;
int tupnatts; /* physical number of columns in tuple */
int tuplogcols; /* # of nondeleted columns in tuple */
int colindex; /* physical column index */
List *newtlist; /* new non-junk tlist entries */
List *junkattrs; /* new junk tlist entries */
/*
* 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.
*
* XXX Note that if rettype is RECORD, the IsBinaryCoercible check
* will succeed for any composite restype. For the moment we rely on
* runtime type checking to catch any discrepancy, but it'd be nice to
* do better at parse time.
*/
if (tlistlen == 1)
{
TargetEntry *tle = (TargetEntry *) linitial(tlist);
Assert(!tle->resjunk);
restype = exprType((Node *) tle->expr);
if (IsBinaryCoercible(restype, rettype))
{
if (modifyTargetList && restype != rettype)
{
tle->expr = (Expr *) makeRelabelType(tle->expr,
rettype,
-1,
get_typcollation(rettype),
COERCE_IMPLICIT_CAST);
/* Relabel is dangerous if sort/group or setop column */
if (tle->ressortgroupref != 0 || parse->setOperations)
*modifyTargetList = true;
}
/* Set up junk filter if needed */
if (junkFilter)
{
TupleTableSlot *slot =
MakeSingleTupleTableSlot(NULL, &TTSOpsMinimalTuple);
*junkFilter = ExecInitJunkFilter(tlist, slot);
}
return false; /* NOT returning whole tuple */
}
}
/*
* Is the rowtype fixed, or determined only at runtime? (Note we
* cannot see TYPEFUNC_COMPOSITE_DOMAIN here.)
*/
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)
{
TupleTableSlot *slot;
slot = MakeSingleTupleTableSlot(NULL, &TTSOpsMinimalTuple);
*junkFilter = ExecInitJunkFilter(tlist, slot);
}
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. For deleted attributes, insert NULL
* result columns if the caller asked for that.
*/
tupnatts = tupdesc->natts;
tuplogcols = 0; /* we'll count nondeleted cols as we go */
colindex = 0;
newtlist = NIL; /* these are only used if modifyTargetList */
junkattrs = NIL;
foreach(lc, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(lc);
Form_pg_attribute attr;
Oid tletype;
Oid atttype;
if (tle->resjunk)
{
if (modifyTargetList)
junkattrs = lappend(junkattrs, tle);
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 = TupleDescAttr(tupdesc, colindex - 1);
if (attr->attisdropped && modifyTargetList)
{
Expr *null_expr;
/* The type of the null we insert isn't important */
null_expr = (Expr *) makeConst(INT4OID,
-1,
InvalidOid,
sizeof(int32),
(Datum) 0,
true, /* isnull */
true /* byval */ );
newtlist = lappend(newtlist,
makeTargetEntry(null_expr,
colindex,
NULL,
false));
/* NULL insertion is dangerous in a setop */
if (parse->setOperations)
*modifyTargetList = true;
}
} 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 (modifyTargetList)
{
if (tletype != atttype)
{
tle->expr = (Expr *) makeRelabelType(tle->expr,
atttype,
-1,
get_typcollation(atttype),
COERCE_IMPLICIT_CAST);
/* Relabel is dangerous if sort/group or setop column */
if (tle->ressortgroupref != 0 || parse->setOperations)
*modifyTargetList = true;
}
tle->resno = colindex;
newtlist = lappend(newtlist, tle);
}
}
/* remaining columns in tupdesc had better all be dropped */
for (colindex++; colindex <= tupnatts; colindex++)
{
if (!TupleDescAttr(tupdesc, colindex - 1)->attisdropped)
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.")));
if (modifyTargetList)
{
Expr *null_expr;
/* The type of the null we insert isn't important */
null_expr = (Expr *) makeConst(INT4OID,
-1,
InvalidOid,
sizeof(int32),
(Datum) 0,
true, /* isnull */
true /* byval */ );
newtlist = lappend(newtlist,
makeTargetEntry(null_expr,
colindex,
NULL,
false));
/* NULL insertion is dangerous in a setop */
if (parse->setOperations)
*modifyTargetList = true;
}
}
if (modifyTargetList)
{
/* ensure resjunk columns are numbered correctly */
foreach(lc, junkattrs)
{
TargetEntry *tle = (TargetEntry *) lfirst(lc);
tle->resno = colindex++;
}
/* replace the tlist with the modified one */
*tlist_ptr = list_concat(newtlist, junkattrs);
}
/* Set up junk filter if needed */
if (junkFilter)
{
TupleTableSlot *slot =
MakeSingleTupleTableSlot(NULL, &TTSOpsMinimalTuple);
*junkFilter = ExecInitJunkFilterConversion(tlist,
CreateTupleDescCopy(tupdesc),
slot);
}
/* 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
*/
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;
/* private fields will be set by postquel_start */
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 bool
sqlfunction_receive(TupleTableSlot *slot, DestReceiver *self)
{
DR_sqlfunction *myState = (DR_sqlfunction *) self;
/* Filter tuple as needed */
slot = ExecFilterJunk(myState->filter, slot);
/* Store the filtered tuple into the tuplestore */
tuplestore_puttupleslot(myState->tstore, slot);
return true;
}
/*
* sqlfunction_shutdown --- executor end
*/
static void
sqlfunction_shutdown(DestReceiver *self)
{
/* no-op */
}
/*
* sqlfunction_destroy --- release DestReceiver object
*/
static void
sqlfunction_destroy(DestReceiver *self)
{
pfree(self);
}
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