Re: pg_dump --if-exists --clean when drop index that is partition of a partitioned index

On Mon, Apr 14, 2025 at 2:09 PM Pavel Stehule <pavel.stehule@gmail.com> wrote:
>
> Hi
>
> po 14. 4. 2025 v 7:54 odesílatel jian he <jian.universality@gmail.com> napsal:
>>
>> hi.
>>
>> CREATE TABLE tp(c int, a int, b int) PARTITION BY RANGE (b);
>> CREATE TABLE tp_1(c int, a int, b int);
>> ALTER TABLE tp ATTACH PARTITION tp_1 FOR VALUES FROM (0) TO (1);
>> CREATE INDEX t_a_idx ON tp_1(a);
>> CREATE INDEX tp_a_idx ON tp(a);
>>
>> pg_dump  --schema=public --if-exists --clean --no-statistics
>> --no-owner --no-data --table-and-children=tp > 1.sql
>> pg_dump output file 1.sql excerpts:
>> ----
>> DROP INDEX IF EXISTS public.t_a_idx;
>> DROP INDEX IF EXISTS public.tp_a_idx;
>> DROP TABLE IF EXISTS public.tp_1;
>> DROP TABLE IF EXISTS public.tp;
>> ----
>> if you execute the
>> DROP INDEX IF EXISTS public.t_a_idx;
>>
>> ERROR:  cannot drop index t_a_idx because index tp_a_idx requires it
>> HINT:  You can drop index tp_a_idx instead.
>>
>> Is this pg_dump output what we expected?
>>
>
> It is a bug, I think, the implementation of these parts of code is older than partitioning support, and doesn't do necessary detach.
>


seems pretty easy to fix.
we only need dropStmt when IndxInfo->parentidx oid is invalid.

+        if (!OidIsValid(indxinfo->parentidx))
+            appendPQExpBuffer(delq, "DROP INDEX %s;\n", qqindxname);

I have tested the above changes on PG11, master.