-
+
<application>PL/pgSQL</application> - <acronym>SQL</acronym> Procedural Language
PL/pgSQL functions can also be declared to return
a set, or table, of any data type they can return a single
instance of. Such a function generates its output by executing
- RETURN NEXT for each desired element of the result set.
+ RETURN NEXT for each desired element of the result
+ set, or by using RETURN QUERY to output the result of
+ evaluating a query.
-
<command>RETURN NEXT</>
+
<command>RETURN NEXT</> and <command>RETURN QUERY</command>
+
+ in PL/PgSQL
+
+
+ in PL/PgSQL
+
RETURN NEXT expression;
+RETURN QUERY query;
When a
PL/pgSQL function is declared to return SETOF sometype, the procedure
to follow is slightly different. In that case, the individual
- items to return are specified in RETURN NEXT
- commands, and then a final RETURN command
- with no argument is used to indicate that the function has
- finished executing. RETURN NEXT can be used
- with both scalar and composite data types; with a composite result
- type, an entire table
of results will be returned.
+ items to return are specified by a sequence of RETURN
+ NEXT or RETURN QUERY commands, and
+ then a final RETURN command with no argument
+ is used to indicate that the function has finished executing.
+ RETURN NEXT can be used with both scalar and
+ composite data types; with a composite result type, an entire
+ table
of results will be returned.
+ RETURN QUERY appends the results of executing
+ a query to the function's result set. RETURN
+ NEXT and RETURN QUERY can be freely
+ intermixed in a single set-returning function, in which case
+ their results will be concatenated.
- RETURN NEXT does not actually return from the
- function — it simply saves away the value of the expression.
- Execution then continues with the next statement in
- the
PL/pgSQL function. As successive- RETURN NEXT commands are executed, the result
- set is built up. A final RETURN, which should
- have no argument, causes control to exit the function (or you can
- just let control reach the end of the function).
+ RETURN NEXT and RETURN
+ QUERY do not actually return from the function —
+ they simply append zero or more rows to the function's result
+ set. Execution then continues with the next statement in the
+
PL/pgSQL function. As successive+ RETURN NEXT or RETURN
+ QUERY commands are executed, the result set is built
+ up. A final RETURN, which should have no
+ argument, causes control to exit the function (or you can just
+ let control reach the end of the function).
If you declared the function with output parameters, write just
RETURN NEXT with no expression. On each
- execution, the current values
- of the output parameter variable(s) will be saved for eventual return
- as a row of the result.
- Note that you must declare the function as returning
- SETOF record when there are
- multiple output parameters, or
- SETOF sometype when there is
- just one output parameter of type sometype, in
- order to create a set-returning function with output parameters.
+ execution, the current values of the output parameter
+ variable(s) will be saved for eventual return as a row of the
+ result. Note that you must declare the function as returning
+ SETOF record when there are multiple output
+ parameters, or SETOF sometype
+ when there is just one output parameter of type
+ sometype, in order to create a set-returning
+ function with output parameters.
- Functions that use RETURN NEXT should be
- called in the following fashion:
+ Functions that use RETURN NEXT or
+ RETURN QUERY should be called in the
+ following fashion:
SELECT * FROM some_func();
The current implementation of RETURN NEXT
-
for PL/pgSQL> stores the entire result set+ and RETURN QUERY> stores the entire result set
before returning from the function, as discussed above. That
means that if a
PL/pgSQL function produces a very large result set, performance might be poor: data will be
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.104 2007/07/16 17:01:10 tgl Exp $
+ * $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.105 2007/07/25 04:19:08 neilc Exp $
*
*-------------------------------------------------------------------------
*/
static PLpgSQL_stmt_fetch *read_fetch_direction(void);
static PLpgSQL_stmt *make_return_stmt(int lineno);
static PLpgSQL_stmt *make_return_next_stmt(int lineno);
+static PLpgSQL_stmt *make_return_query_stmt(int lineno);
static void check_assignable(PLpgSQL_datum *datum);
static void read_into_target(PLpgSQL_rec **rec, PLpgSQL_row **row,
bool *strict);
%token K_NULL
%token K_OPEN
%token K_OR
+%token K_QUERY
%token K_PERFORM
%token K_ROW_COUNT
%token K_RAISE
{
$$ = make_return_next_stmt($2);
}
+ else if (tok == K_QUERY)
+ {
+ $$ = make_return_query_stmt($2);
+ }
else
{
plpgsql_push_back_token(tok);
if (plpgsql_curr_compile->fn_retset)
{
if (yylex() != ';')
- yyerror("RETURN cannot have a parameter in function returning set; use RETURN NEXT");
+ yyerror("RETURN cannot have a parameter in function "
+ "returning set; use RETURN NEXT or RETURN QUERY");
}
else if (plpgsql_curr_compile->out_param_varno >= 0)
{
}
+static PLpgSQL_stmt *
+make_return_query_stmt(int lineno)
+{
+ PLpgSQL_stmt_return_query *new;
+
+ if (!plpgsql_curr_compile->fn_retset)
+ yyerror("cannot use RETURN QUERY in a non-SETOF function");
+
+ new = palloc0(sizeof(PLpgSQL_stmt_return_query));
+ new->cmd_type = PLPGSQL_STMT_RETURN_QUERY;
+ new->lineno = lineno;
+ new->query = read_sql_construct(';', 0, ")", "", false, true, NULL);
+
+ return (PLpgSQL_stmt *) new;
+}
+
+
static void
check_assignable(PLpgSQL_datum *datum)
{
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.198 2007/07/15 02:15:04 tgl Exp $
+ * $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.199 2007/07/25 04:19:08 neilc Exp $
*
*-------------------------------------------------------------------------
*/
PLpgSQL_stmt_return *stmt);
static int exec_stmt_return_next(PLpgSQL_execstate *estate,
PLpgSQL_stmt_return_next *stmt);
+static int exec_stmt_return_query(PLpgSQL_execstate *estate,
+ PLpgSQL_stmt_return_query *stmt);
static int exec_stmt_raise(PLpgSQL_execstate *estate,
PLpgSQL_stmt_raise *stmt);
static int exec_stmt_execsql(PLpgSQL_execstate *estate,
rc = exec_stmt_return_next(estate, (PLpgSQL_stmt_return_next *) stmt);
break;
+ case PLPGSQL_STMT_RETURN_QUERY:
+ rc = exec_stmt_return_query(estate, (PLpgSQL_stmt_return_query *) stmt);
+ break;
+
case PLPGSQL_STMT_RAISE:
rc = exec_stmt_raise(estate, (PLpgSQL_stmt_raise *) stmt);
break;
return PLPGSQL_RC_OK;
}
+/* ----------
+ * exec_stmt_return_query Evaluate a query and add it to the
+ * list of tuples returned by the current
+ * SRF.
+ * ----------
+ */
+static int
+exec_stmt_return_query(PLpgSQL_execstate *estate,
+ PLpgSQL_stmt_return_query *stmt)
+{
+ Portal portal;
+
+ if (!estate->retisset)
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("cannot use RETURN QUERY in a non-SETOF function")));
+
+ if (estate->tuple_store == NULL)
+ exec_init_tuple_store(estate);
+
+ exec_run_select(estate, stmt->query, 0, &portal);
+
+ if (!compatible_tupdesc(estate->rettupdesc, portal->tupDesc))
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("structure of query does not match function result type")));
+
+ while (true)
+ {
+ MemoryContext old_cxt;
+ int i;
+
+ SPI_cursor_fetch(portal, true, 50);
+ if (SPI_processed == 0)
+ break;
+
+ old_cxt = MemoryContextSwitchTo(estate->tuple_store_cxt);
+ for (i = 0; i < SPI_processed; i++)
+ {
+ HeapTuple tuple = SPI_tuptable->vals[i];
+ tuplestore_puttuple(estate->tuple_store, tuple);
+ }
+ MemoryContextSwitchTo(old_cxt);
+
+ SPI_freetuptable(SPI_tuptable);
+ }
+
+ SPI_freetuptable(SPI_tuptable);
+ SPI_cursor_close(portal);
+
+ return PLPGSQL_RC_OK;
+}
+
static void
exec_init_tuple_store(PLpgSQL_execstate *estate)
{
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_funcs.c,v 1.62 2007/07/20 16:23:34 petere Exp $
+ * $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_funcs.c,v 1.63 2007/07/25 04:19:08 neilc Exp $
*
*-------------------------------------------------------------------------
*/
return "RETURN";
case PLPGSQL_STMT_RETURN_NEXT:
return "RETURN NEXT";
+ case PLPGSQL_STMT_RETURN_QUERY:
+ return "RETURN QUERY";
case PLPGSQL_STMT_RAISE:
return "RAISE";
case PLPGSQL_STMT_EXECSQL:
static void dump_exit(PLpgSQL_stmt_exit *stmt);
static void dump_return(PLpgSQL_stmt_return *stmt);
static void dump_return_next(PLpgSQL_stmt_return_next *stmt);
+static void dump_return_query(PLpgSQL_stmt_return_query *stmt);
static void dump_raise(PLpgSQL_stmt_raise *stmt);
static void dump_execsql(PLpgSQL_stmt_execsql *stmt);
static void dump_dynexecute(PLpgSQL_stmt_dynexecute *stmt);
case PLPGSQL_STMT_RETURN_NEXT:
dump_return_next((PLpgSQL_stmt_return_next *) stmt);
break;
+ case PLPGSQL_STMT_RETURN_QUERY:
+ dump_return_query((PLpgSQL_stmt_return_query *) stmt);
+ break;
case PLPGSQL_STMT_RAISE:
dump_raise((PLpgSQL_stmt_raise *) stmt);
break;
printf("\n");
}
+static void
+dump_return_query(PLpgSQL_stmt_return_query *stmt)
+{
+ dump_ind();
+ printf("RETURN QUERY ");
+ dump_expr(stmt->query);
+ printf("\n");
+}
+
static void
dump_raise(PLpgSQL_stmt_raise *stmt)
{
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/pl/plpgsql/src/plpgsql.h,v 1.90 2007/07/16 17:01:11 tgl Exp $
+ * $PostgreSQL: pgsql/src/pl/plpgsql/src/plpgsql.h,v 1.91 2007/07/25 04:19:09 neilc Exp $
*
*-------------------------------------------------------------------------
*/
PLPGSQL_STMT_EXIT,
PLPGSQL_STMT_RETURN,
PLPGSQL_STMT_RETURN_NEXT,
+ PLPGSQL_STMT_RETURN_QUERY,
PLPGSQL_STMT_RAISE,
PLPGSQL_STMT_EXECSQL,
PLPGSQL_STMT_DYNEXECUTE,
int retvarno;
} PLpgSQL_stmt_return_next;
+typedef struct
+{ /* RETURN QUERY statement */
+ int cmd_type;
+ int lineno;
+ PLpgSQL_expr *query;
+} PLpgSQL_stmt_return_query;
+
typedef struct
{ /* RAISE statement */
int cmd_type;
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/pl/plpgsql/src/scan.l,v 1.57 2007/04/29 01:21:09 neilc Exp $
+ * $PostgreSQL: pgsql/src/pl/plpgsql/src/scan.l,v 1.58 2007/07/25 04:19:09 neilc Exp $
*
*-------------------------------------------------------------------------
*/
default { return K_DEFAULT; }
diagnostics { return K_DIAGNOSTICS; }
else { return K_ELSE; }
-elseif { return K_ELSIF; }
-elsif { return K_ELSIF; }
+elseif { return K_ELSIF; }
+elsif { return K_ELSIF; }
end { return K_END; }
exception { return K_EXCEPTION; }
execute { return K_EXECUTE; }
open { return K_OPEN; }
or { return K_OR; }
perform { return K_PERFORM; }
+query { return K_QUERY; }
raise { return K_RAISE; }
rename { return K_RENAME; }
result_oid { return K_RESULT_OID; }
(1 row)
drop function pl_qual_names(int);
+-- tests for RETURN QUERY
+create function ret_query1(out int, out int) returns setof record as $$
+begin
+ $1 := -1;
+ $2 := -2;
+ return next;
+ return query select x + 1, x * 10 from generate_series(0, 10) s (x);
+ return next;
+end;
+$$ language plpgsql;
+select * from ret_query1();
+ column1 | column2
+---------+---------
+ -1 | -2
+ 1 | 0
+ 2 | 10
+ 3 | 20
+ 4 | 30
+ 5 | 40
+ 6 | 50
+ 7 | 60
+ 8 | 70
+ 9 | 80
+ 10 | 90
+ 11 | 100
+ -1 | -2
+(13 rows)
+
+create type record_type as (x text, y int, z boolean);
+create or replace function ret_query2(lim int) returns setof record_type as $$
+begin
+ return query select md5(s.x::text), s.x, s.x > 0
+ from generate_series(-8, lim) s (x) where s.x % 2 = 0;
+end;
+$$ language plpgsql;
+select * from ret_query2(8);
+ x | y | z
+----------------------------------+----+---
+ a8d2ec85eaf98407310b72eb73dda247 | -8 | f
+ 596a3d04481816330f07e4f97510c28f | -6 | f
+ 0267aaf632e87a63288a08331f22c7c3 | -4 | f
+ 5d7b9adcbe1c629ec722529dd12e5129 | -2 | f
+ cfcd208495d565ef66e7dff9f98764da | 0 | f
+ c81e728d9d4c2f636f067f89cc14862c | 2 | t
+ a87ff679a2f3e71d9181a67b7542122c | 4 | t
+ 1679091c5a880faf6fb5e6087eb1b2dc | 6 | t
+ c9f0f895fb98ab9159f51fd0297e236d | 8 | t
+(9 rows)
+
select pl_qual_names(42);
drop function pl_qual_names(int);
+
+-- tests for RETURN QUERY
+create function ret_query1(out int, out int) returns setof record as $$
+begin
+ $1 := -1;
+ $2 := -2;
+ return next;
+ return query select x + 1, x * 10 from generate_series(0, 10) s (x);
+ return next;
+end;
+$$ language plpgsql;
+
+select * from ret_query1();
+
+create type record_type as (x text, y int, z boolean);
+
+create or replace function ret_query2(lim int) returns setof record_type as $$
+begin
+ return query select md5(s.x::text), s.x, s.x > 0
+ from generate_series(-8, lim) s (x) where s.x % 2 = 0;
+end;
+$$ language plpgsql;
+
+select * from ret_query2(8);
\ No newline at end of file
projects / postgresql.git / commitdiff