Re: patch for pg_autovacuum 8.0.x prevent segv for dropped

Small nit: please observe postgres community conventions regarding

a) indentation (BSD style, tabsize 4) and
b) diff type (context, not unidiff)

The patch itself looks ok to me.

cheers

andrew

daveg wrote:

>Apologies if this is old news, but pg_autovacuum in 8.0.x has the bad habit
>of SEGVing and exiting when a table gets dropped out from under it. This
>creates problems if you rely on pg_autovacuum for the bulk of your vacuuming
>as it forgets it's statistics when it is restarted and so will skip some
>desireable vacuums.
>
>I looked at the new autovacuum in 8.1 and it appears from casual inspection
>not to have the same problem.
>
>Below is a patch for this that should apply against any 8.0.x. The change
>verifies that the catalog query returned some rows before accessing the row
>data.
>
>-dg
>
>diff -Naur source/postgresql-8.0.2/contrib/pg_autovacuum/pg_autovacuum.c
build/postgresql-8.0.2/contrib/pg_autovacuum/pg_autovacuum.c
>--- source/postgresql-8.0.2/contrib/pg_autovacuum/pg_autovacuum.c    2005-04-02 16:02:03.000000000 -0800
>+++ build/postgresql-8.0.2/contrib/pg_autovacuum/pg_autovacuum.c    2005-09-28 22:15:25.428710172 -0700
>@@ -1013,6 +1013,7 @@
> static void
> perform_maintenance_command(db_info * dbi, tbl_info * tbl, int operation)
> {
>+    PGresult    *res;
>     char        buf[256];
>
>     /*
>@@ -1069,10 +1070,16 @@
>         fflush(LOGOUTPUT);
>     }
>
>-    send_query(buf, dbi);
>-
>-    update_table_thresholds(dbi, tbl, operation);
>-
>+    res = send_query(buf, dbi);
>+    if (PQntuples(res)) {
>+        update_table_thresholds(dbi, tbl, operation);
>+    } else {
>+        if (args->debug >= 1) {
>+            sprintf(logbuffer, "Cannot refind table %s", tbl->table_name);
>+            log_entry(logbuffer, LVL_DEBUG);
>+            fflush(LOGOUTPUT);
>+        }
>+    }
>     if (args->debug >= 2)
>         print_table_info(tbl);
> }
>
>