The attached patch implements spi_query() and spi_fetchrow() functions
for PL/Perl, to avoid loading the entire result set into memory as the
existing spi_exec_query() function does.
Here's how one might use the new functions:
$x = spi_query(select ...);
while (defined ($y = spi_fetchrow($x))) {
...
return_next(...);
}
The changes do not affect the spi_exec_query() interface in any way.
Comments welcome.
-- ams
--- pl/plperl/spi_internal.h~ 2005-06-12 15:45:31.0 +0530
+++ pl/plperl/spi_internal.h2005-06-12 15:45:59.0 +0530
@@ -18,3 +18,5 @@
/* this is actually in plperl.c */
HV*plperl_spi_exec(char *, int);
void plperl_return_next(SV *);
+SV *plperl_spi_query(char *);
+SV *plperl_spi_fetchrow(char *);
--- pl/plperl/SPI.xs~ 2005-06-05 14:49:59.0 +0530
+++ pl/plperl/SPI.xs2005-06-12 15:31:37.0 +0530
@@ -103,5 +103,21 @@
CODE:
plperl_return_next(rv);
+SV *
+spi_spi_query(query)
+ char *query;
+ CODE:
+ RETVAL = plperl_spi_query(query);
+ OUTPUT:
+ RETVAL
+
+SV *
+spi_spi_fetchrow(cursor)
+ char *cursor;
+ CODE:
+ RETVAL = plperl_spi_fetchrow(cursor);
+ OUTPUT:
+ RETVAL
+
BOOT:
items = 0; /* avoid 'unused variable' warning */
--- pl/plperl/plperl.c~ 2005-06-29 07:40:25.132358971 +0530
+++ pl/plperl/plperl.c 2005-06-29 14:29:30.269050201 +0530
@@ -118,6 +118,7 @@
void plperl_init(void);
HV*plperl_spi_exec(char *query, int limit);
+SV*plperl_spi_query(char *);
static Datum plperl_func_handler(PG_FUNCTION_ARGS);
@@ -225,6 +226,7 @@
$PLContainer-permit_only(':default');
$PLContainer-permit(qw[:base_math !:base_io sort time]);
$PLContainer-share(qw[elog spi_exec_query return_next
+ spi_query spi_fetchrow
DEBUG LOG INFO NOTICE WARNING ERROR %_SHARED ]);
;
@@ -1519,3 +1521,77 @@
heap_freetuple(tuple);
MemoryContextSwitchTo(cxt);
}
+
+
+SV *
+plperl_spi_query(char *query)
+{
+ SV *cursor;
+
+ MemoryContext oldcontext = CurrentMemoryContext;
+ ResourceOwner oldowner = CurrentResourceOwner;
+
+ BeginInternalSubTransaction(NULL);
+ MemoryContextSwitchTo(oldcontext);
+
+ PG_TRY();
+ {
+ void *plan;
+ Portal portal = NULL;
+
+ plan = SPI_prepare(query, 0, NULL);
+ if (plan)
+ portal = SPI_cursor_open(NULL, plan, NULL, NULL, false);
+ if (portal)
+ cursor = newSVpv(portal-name, 0);
+ else
+ cursor = newSV(0);
+
+ ReleaseCurrentSubTransaction();
+ MemoryContextSwitchTo(oldcontext);
+ CurrentResourceOwner = oldowner;
+ SPI_restore_connection();
+ }
+ PG_CATCH();
+ {
+ ErrorData *edata;
+
+ MemoryContextSwitchTo(oldcontext);
+ edata = CopyErrorData();
+ FlushErrorState();
+
+ RollbackAndReleaseCurrentSubTransaction();
+ MemoryContextSwitchTo(oldcontext);
+ CurrentResourceOwner = oldowner;
+
+ SPI_restore_connection();
+ croak(%s, edata-message);
+ return NULL;
+ }
+ PG_END_TRY();
+
+ return cursor;
+}
+
+
+SV *
+plperl_spi_fetchrow(char *cursor)
+{
+ SV *row = newSV(0);
+ Portal p = SPI_cursor_find(cursor);
+
+ if (!p)
+ return row;
+
+ SPI_cursor_fetch(p, true, 1);
+ if (SPI_processed == 0) {
+ SPI_cursor_close(p);
+ return row;
+ }
+
+ row = plperl_hash_from_tuple(SPI_tuptable-vals[0],
+
SPI_tuptable-tupdesc);
+ SPI_freetuptable(SPI_tuptable);
+
+ return row;
+}
--- pl/plperl/sql/plperl.sql~ 2005-06-29 08:51:26.602006376 +0530
+++ pl/plperl/sql/plperl.sql2005-06-29 15:04:25.744032754 +0530
@@ -247,3 +247,16 @@
return;
$$ language plperl;
SELECT * from perl_srf_rn() AS (f1 INTEGER, f2 TEXT, f3 TEXT);
+
+--
+-- Test spi_query/spi_fetchrow
+--
+
+CREATE OR REPLACE FUNCTION perl_spi_func() RETURNS SETOF INTEGER AS $$
+$x = spi_query(select 1 as a union select 2 as a);
+while (defined ($y = spi_fetchrow($x))) {
+return_next($y-{a});
+}
+return;
+$$ LANGUAGE plperl;
+SELECT * from perl_spi_func();
--- pl/plperl/expected/plperl.out~ 2005-06-29 15:04:37.749935678 +0530
+++ pl/plperl/expected/plperl.out 2005-06-29 15:06:08.967002756 +0530
@@ -350,3 +350,20 @@
3 | Hello | PL/Perl
(3 rows)
+--
+-- Test spi_query/spi_fetchrow
+--
+CREATE OR REPLACE FUNCTION perl_spi_func() RETURNS SETOF INTEGER AS $$
+$x = spi_query(select 1 as a union select 2 as a);
+while (defined ($y =
