Fix typo in freeze_table_age implementation

The original code used freeze_min_age instead of freeze_table_age.  The
main consequence of this mistake is that lowering freeze_min_age would
cause full-table scans to occur much more frequently, which causes
serious issues because the number of writes required is much larger.
That feature (freeze_min_age) is supposed to affect only how soon tuples
are frozen; some pages should still be skipped due to the visibility
map.

Backpatch to 8.4, where the freeze_table_age feature was introduced.

Report and patch from Andres Freund

diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index a37a54e5b42fddbbbb19d5f6a584562047714150..4800b4376404157c504e298590f003f398edbbf0 100644 (file)
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -449,7 +449,7 @@ vacuum_set_xid_limits(int freeze_min_age,
         * VACUUM schedule, the nightly VACUUM gets a chance to freeze tuples
         * before anti-wraparound autovacuum is launched.
         */
-       freezetable = freeze_min_age;
+       freezetable = freeze_table_age;
        if (freezetable < 0)
            freezetable = vacuum_freeze_table_age;
        freezetable = Min(freezetable, autovacuum_freeze_max_age * 0.95);