Hello,
this small patch complete MOVE support in plpgsql and equalize plpgsql
syntax with sql syntax.
There are possible new directions:
FORWARD expr, FORWARD ALL, BACKWARD expr, BACKWARD all.
These directions are not allowed for FETCH statement, because returns more rows.
This patch is related to ToDo issue: Review handling of MOVE and FETCH
Regards
Pavel Stehule
p.s. Scrollable cursors are supported yet in plpgsql. Do you know,
somebody, why this point is in ToDo (plpgsql) still?
*** ./doc/src/sgml/plpgsql.sgml.orig 2009-08-27 17:14:26.926410144 +0200
--- ./doc/src/sgml/plpgsql.sgml 2009-08-27 17:32:47.928407934 +0200
***************
*** 2656,2670 ****
<para>
The options for the <replaceable>direction</replaceable> clause are
! the same as for <command>FETCH</>, namely
<literal>NEXT</>,
<literal>PRIOR</>,
<literal>FIRST</>,
<literal>LAST</>,
<literal>ABSOLUTE</> <replaceable>count</replaceable>,
<literal>RELATIVE</> <replaceable>count</replaceable>,
! <literal>FORWARD</>, or
! <literal>BACKWARD</>.
Omitting <replaceable>direction</replaceable> is the same
as specifying <literal>NEXT</>.
<replaceable>direction</replaceable> values that require moving
--- 2656,2670 ----
<para>
The options for the <replaceable>direction</replaceable> clause are
! similar as for <command>FETCH</>, namely
<literal>NEXT</>,
<literal>PRIOR</>,
<literal>FIRST</>,
<literal>LAST</>,
<literal>ABSOLUTE</> <replaceable>count</replaceable>,
<literal>RELATIVE</> <replaceable>count</replaceable>,
! <literal>FORWARD</> <optional> <replaceable>count</replaceable> | <literal>ALL</> </optional>, or
! <literal>BACKWARD</> <optional> <replaceable>count</replaceable> | <literal>ALL</> </optional>.
Omitting <replaceable>direction</replaceable> is the same
as specifying <literal>NEXT</>.
<replaceable>direction</replaceable> values that require moving
*** ./src/pl/plpgsql/src/gram.y.orig 2009-08-26 22:43:23.138239357 +0200
--- ./src/pl/plpgsql/src/gram.y 2009-08-27 08:18:13.418238086 +0200
***************
*** 72,77 ****
--- 72,79 ----
int until, const char *expected);
static List *read_raise_options(void);
+ static PLpgSQL_stmt_fetch *complete_direction(PLpgSQL_stmt_fetch *fetch, bool *check_FROM);
+
%}
%expect 0
***************
*** 178,183 ****
--- 180,186 ----
* Keyword tokens
*/
%token K_ALIAS
+ %token K_ALL
%token K_ASSIGN
%token K_BEGIN
%token K_BY
***************
*** 1621,1626 ****
--- 1624,1635 ----
if (yylex() != ';')
yyerror("syntax error");
+
+ if (!fetch->returns_row)
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("statement FETCH returns more rows."),
+ errhint("Multirows fetch are not allowed in PL/pgSQL.")));
fetch->lineno = $2;
fetch->rec = rec;
***************
*** 2252,2257 ****
--- 2261,2271 ----
}
+ /*
+ * Read FETCH or MOVE statement direction. For statement for are only
+ * one row directions allowed. MOVE statement can use FORWARD [(n|ALL)],
+ * BACKWARD [(n|ALL)] directions too.
+ */
static PLpgSQL_stmt_fetch *
read_fetch_direction(void)
{
***************
*** 2269,2274 ****
--- 2283,2289 ----
fetch->direction = FETCH_FORWARD;
fetch->how_many = 1;
fetch->expr = NULL;
+ fetch->returns_row = true;
/*
* Most of the direction keywords are not plpgsql keywords, so we
***************
*** 2313,2323 ****
}
else if (pg_strcasecmp(yytext, "forward") == 0)
{
! /* use defaults */
}
else if (pg_strcasecmp(yytext, "backward") == 0)
{
fetch->direction = FETCH_BACKWARD;
}
else if (tok != T_SCALAR)
{
--- 2328,2339 ----
}
else if (pg_strcasecmp(yytext, "forward") == 0)
{
! fetch = complete_direction(fetch, &check_FROM);
}
else if (pg_strcasecmp(yytext, "backward") == 0)
{
fetch->direction = FETCH_BACKWARD;
+ fetch = complete_direction(fetch, &check_FROM);
}
else if (tok != T_SCALAR)
{
***************
*** 2346,2351 ****
--- 2362,2408 ----
}
+ /*
+ * Allows directions:
+ * FORWARD expr, FORWARD ALL, FORWARD
+ * BACKWARD expr, BACKWARD ALL, BACKWARD
+ *
+ * so plpgsql should fully support PostgreSQL's MOVE statement.
+ */
+ static PLpgSQL_stmt_fetch *
+ complete_direction(PLpgSQL_stmt_fetch *fetch, bool *check_FROM)
+ {
+ int tok;
+ PLpgSQL_expr *expr;
+
+ tok = yylex();
+ if (tok == K_FROM || tok == K_IN)
+ {
+ *check_FROM = false;
+
+ return fetch;
+ }
+
+ if (tok == K_ALL)
+ {
+ fetch->how_many = fetch->direction == FETCH_FORWARD ? -1 : 0;
+ fetch->direction = FETCH_ABSOLUTE;
+ fetch->returns_row = false;
+ *check_FROM = true;
+
+ return fetch;
+ }
+
+ plpgsql_push_back_token(tok);
+ expr = read_sql_expression2(K_FROM, K_IN,
+ "FROM or IN",
+ NULL);
+ fetch->returns_row = false;
+ *check_FROM = false;
+
+ return fetch;
+ }
+
static PLpgSQL_stmt *
make_return_stmt(int lineno)
{
*** ./src/pl/plpgsql/src/plpgsql.h.orig 2009-08-27 07:46:45.051237969 +0200
--- ./src/pl/plpgsql/src/plpgsql.h 2009-08-27 07:58:57.816237398 +0200
***************
*** 520,525 ****
--- 520,526 ----
int how_many; /* count, if constant (expr is NULL) */
PLpgSQL_expr *expr; /* count, if expression */
bool is_move; /* is this a fetch or move? */
+ bool returns_row; /* returns one or more rows? */
} PLpgSQL_stmt_fetch;
*** ./src/pl/plpgsql/src/scan.l.orig 2009-08-27 07:55:10.058239657 +0200
--- ./src/pl/plpgsql/src/scan.l 2009-08-27 07:55:19.387238292 +0200
***************
*** 147,152 ****
--- 147,153 ----
= { return K_ASSIGN; }
\.\. { return K_DOTDOT; }
alias { return K_ALIAS; }
+ all { return K_ALL; }
begin { return K_BEGIN; }
by { return K_BY; }
case { return K_CASE; }
*** ./src/test/regress/expected/plpgsql.out.orig 2009-08-27 17:07:50.785412959 +0200
--- ./src/test/regress/expected/plpgsql.out 2009-08-27 17:06:17.000000000 +0200
***************
*** 3027,3032 ****
--- 3027,3055 ----
create or replace function sc_test() returns setof integer as $$
declare
+ c refcursor;
+ x integer;
+ begin
+ open c scroll for execute 'select f1 from int4_tbl';
+ fetch last from c into x;
+ while found loop
+ return next x;
+ move backward 2 from c;
+ fetch relative -1 from c into x;
+ end loop;
+ close c;
+ end;
+ $$ language plpgsql;
+ select * from sc_test();
+ sc_test
+ -------------
+ -2147483647
+ -123456
+ 0
+ (3 rows)
+
+ create or replace function sc_test() returns setof integer as $$
+ declare
c cursor for select * from generate_series(1, 10);
x integer;
begin
***************
*** 3052,3057 ****
--- 3075,3109 ----
9
(3 rows)
+ create or replace function sc_test() returns setof integer as $$
+ declare
+ c cursor for select * from generate_series(1, 10);
+ x integer;
+ begin
+ open c;
+ loop
+ move forward 2 in c;
+ if not found then
+ exit;
+ end if;
+ fetch next from c into x;
+ if found then
+ return next x;
+ end if;
+ end loop;
+ close c;
+ end;
+ $$ language plpgsql;
+ select * from sc_test();
+ sc_test
+ ---------
+ 2
+ 4
+ 6
+ 8
+ 10
+ (5 rows)
+
drop function sc_test();
-- test qualified variable names
create function pl_qual_names (param1 int) returns void as $$
*** ./src/test/regress/sql/plpgsql.sql.orig 2009-08-27 16:56:20.809413381 +0200
--- ./src/test/regress/sql/plpgsql.sql 2009-08-27 17:05:19.340410442 +0200
***************
*** 2513,2518 ****
--- 2513,2538 ----
create or replace function sc_test() returns setof integer as $$
declare
+ c refcursor;
+ x integer;
+ begin
+ open c scroll for execute 'select f1 from int4_tbl';
+ fetch last from c into x;
+ while found loop
+ return next x;
+ move backward 2 from c;
+ fetch relative -1 from c into x;
+ end loop;
+ close c;
+ end;
+ $$ language plpgsql;
+
+ select * from sc_test();
+
+
+
+ create or replace function sc_test() returns setof integer as $$
+ declare
c cursor for select * from generate_series(1, 10);
x integer;
begin
***************
*** 2533,2538 ****
--- 2553,2581 ----
select * from sc_test();
+ create or replace function sc_test() returns setof integer as $$
+ declare
+ c cursor for select * from generate_series(1, 10);
+ x integer;
+ begin
+ open c;
+ loop
+ move forward 2 in c;
+ if not found then
+ exit;
+ end if;
+ fetch next from c into x;
+ if found then
+ return next x;
+ end if;
+ end loop;
+ close c;
+ end;
+ $$ language plpgsql;
+
+ select * from sc_test();
+
+
drop function sc_test();
-- test qualified variable names
--
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