Re: tablecmds: fix bug where index rebuild loses replica identity on partitions

> On Jan 28, 2026, at 10:49, Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com> wrote:
>
>
>
>> On Jan 27, 2026, at 16:30, Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com> wrote:
>>
>>
>>
>>> On Jan 27, 2026, at 15:59, Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com> wrote:
>>>
>>>
>>>
>>>> On Jan 27, 2026, at 15:39, Michael Paquier <michael(at)paquier(dot)xyz> wrote:
>>>>
>>>> On Tue, Jan 27, 2026 at 01:13:32PM +0800, Chao Li wrote:
>>>>> I found this bug while working on a related patch [1].
>>>>>
>>>>> When ALTER TABLE ... ALTER COLUMN TYPE causes an index rebuild, and
>>>>> that index is used as REPLICA IDENTITY on a partitioned table, the
>>>>> replica identity marking on partitions can be silently lost after the
>>>>> rebuild.
>>>>
>>>> I am slightly confused by the tests included in the proposed patch.
>>>> On HEAD, if I undo the proposed changes of tablecmds.c, the tests
>>>> pass. If I run the tests of the patch with the changes of
>>>> tablecmds.c, the tests also pass.
>>>
>>> Oops, that isn’t supposed to be so. I’ll check the test.
>>>
>>
>> Okay, I see the problem is here:
>> ```
>> +CREATE UNIQUE INDEX test_replica_identity_partitioned_pkey ON test_replica_identity_partitioned (id);
>> ```
>>
>> I missed to add column “val” into the index, so that alter type of val didn’t cause index rebuild.
>>
>> Ideally, it’s better to also verify that index OIDs should have changed before and after alter column type, but I haven’t figured out how to do so. Do you have an idea?
>
> I just updated the test to store index OIDs before and after rebuild into 2 temp tables, so that we can compare the OIDs to verify rebuild happens and replica identity preserved.
>
> I tried to port the test to master branch, and the test failed. From the test diff file, we can see replica identity lost on 3 leaf partitions:
> ```
> @@ -360,9 +360,9 @@
> ORDER BY b.index_name;
> index_name | rebuilt | ri_lost
> ---------------------------------------------------+---------+---------
> - test_replica_identity_partitioned_p1_id_val_idx | t | f
> - test_replica_identity_partitioned_p2_1_id_val_idx | t | f
> - test_replica_identity_partitioned_p2_2_id_val_idx | t | f
> + test_replica_identity_partitioned_p1_id_val_idx | t | t
> + test_replica_identity_partitioned_p2_1_id_val_idx | t | t
> + test_replica_identity_partitioned_p2_2_id_val_idx | t | t
> test_replica_identity_partitioned_p2_id_val_idx | t | f
> test_replica_identity_partitioned_pkey | t | f
> (5 rows)
> ```
>
> With this patch, the test passes and all replica identity are preserved.
>
> PFA v3:
> * Enhanced the test.
> * A small change in find_partition_replica_identity_indexes(): if we will not update a partition, then unlock it.
>
> Best regards,
> --
> Chao Li (Evan)
> HighGo Software Co., Ltd.
> https://www.highgo.com/
>
>
>
>
> <v3-0001-tablecmds-fix-bug-where-index-rebuild-loses-repli.patch>

The CF asked for a rebase, thus rebased as v4.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/