On Fri, Feb 21, 2020 at 4:47 PM Masahiko Sawada <masahiko.saw...@2ndquadrant.com> wrote: > Thank you for updating the patch. I tested v4 patch. > > After analyze or autoanalyze on partitioned table n_live_tup and > n_dead_tup are updated. However, TRUNCATE and VACUUM on the > partitioned table don't change these values until invoking analyze or > autoanalyze whereas in normal tables these values are reset or > changed. For example, with your patch: > > * Before > relname | n_live_tup | n_dead_tup | n_mod_since_analyze > ---------+------------+------------+--------------------- > c1 | 11 | 0 | 0 > c2 | 11 | 0 | 0 > c3 | 11 | 0 | 0 > c4 | 11 | 0 | 0 > c5 | 11 | 0 | 0 > parent | 55 | 0 | 0 > (6 rows) > > * After 'TRUNCATE parent' > relname | n_live_tup | n_dead_tup | n_mod_since_analyze > ---------+------------+------------+--------------------- > c1 | 0 | 0 | 0 > c2 | 0 | 0 | 0 > c3 | 0 | 0 | 0 > c4 | 0 | 0 | 0 > c5 | 0 | 0 | 0 > parent | 55 | 0 | 0 > (6 rows) > > * Before > relname | n_live_tup | n_dead_tup | n_mod_since_analyze > ---------+------------+------------+--------------------- > c1 | 0 | 11 | 0 > c2 | 0 | 11 | 0 > c3 | 0 | 11 | 0 > c4 | 0 | 11 | 0 > c5 | 0 | 11 | 0 > parent | 0 | 55 | 0 > (6 rows) > > * After 'VACUUM parent' > relname | n_live_tup | n_dead_tup | n_mod_since_analyze > ---------+------------+------------+--------------------- > c1 | 0 | 0 | 0 > c2 | 0 | 0 | 0 > c3 | 0 | 0 | 0 > c4 | 0 | 0 | 0 > c5 | 0 | 0 | 0 > parent | 0 | 55 | 0 > (6 rows) > > We can make it work correctly but I think perhaps we can skip updating > statistics values of partitioned tables other than n_mod_since_analyze > as the first step. Because if we support also n_live_tup and > n_dead_tup, user might get confused that other statistics values such > as seq_scan, seq_tup_read however are not supported.
+1, that makes sense. Thanks, Amit
