On Tue, May 14, 2024 at 5:49 PM Justin Pryzby <pryzby@telsasoft.com> wrote: > On Thu, May 09, 2024 at 12:51:32AM +0300, Alexander Korotkov wrote: > > > > However, parent's table extended statistics already covers all its > > > > children. > > > > > > => That's the wrong explanation. It's not that "stats on the parent > > > table cover its children". It's that there are two types of stats: > > > stats for the "table hierarchy" and stats for the individual table. > > > That's true for single-column stats as well as for extended stats. > > > In both cases, that's indicated by the inh flag in the code and in the > > > catalog. > > > > > > The right explanation is that extended stats on partitioned tables are > > > not similar to indexes. Indexes on parent table are nothing other than > > > a mechanism to create indexes on the child tables. That's not true for > > > stats. > > > > > > See also my prior messages > > > ZiJW1g2nbQs9ekwK@pryzbyj2023 > > > Zi5Msg74C61DjJKW@pryzbyj2023 > > > > Yes, I understand that parents pg_statistic entry with stainherit == > > true includes statistics for the children. I tried to express this by > > word "covers". But you're right, this is the wrong explanation. > > > > Can I, please, ask you to revise the patch? > > I tried to make this clear but it'd be nice if someone (Tomas/Alvaro?) > would check that this says what's wanted.
Thank you!
I've assembled the patches with the pending fixes. 0001 – The patch by Dmitry Koval for fixing detection of name collision in SPLIT partition operation. Also, I found that name collision detection doesn't work well for MERGE partitions. I've added fix for that to this patch as well. 0002 -– Patch for skipping copy of extended statistics. I would appreciate more feedback about wording, but I'd like to get a correct behavior into the source tree sooner. If the docs and/or comments need further improvements, we can fix that later.
I'm going to push both if no objections.
Thank you for working on this patch set!
Some minor things:
0001:
partition_split.sql
157 +-- Check that detection, that the new partition has the same name as one of
158 +-- the merged partitions, works correctly for temporary partitions
Test for split with comment for merge. Maybe better something like:
"Split partition of a temporary table when one of the partitions after split has the same name as the partition being split"
0002:
analgous -> analogous (maybe better using "like" instead of "analogous to")
heirarchy -> hierarchy
alter_table.sgml:
Maybe in documentation it's better not to provide reasoning, just state how it works:
for consistency with <command>CREATE TABLE PARTITION OF</command> -> similar to <command>CREATE TABLE PARTITION OF</command>
