Re: Assertion failure in smgr.c when using pg_prewarm with partitioned tables

On Fri, May 16, 2025 at 11:51 AM Masahiro Ikeda
<ikedamsh@oss.nttdata.com> wrote:
>
> Thank you for your comments!
>
> I updated the patch to use RELKIND_HAS_STORAGE() as done in
> commit 4623d7144. Please see the v2-0001 patch for the changes.
>
> On 2025-05-15 19:57, Richard Guo wrote:
> > +1.  FWIW, not long ago we fixed a similar Assert failure in
> > contrib/pg_freespacemap by verifying RELKIND_HAS_STORAGE() before
> > trying to access the storage (see 4623d7144).  Wondering if there are
> > other similar issues elsewhere in contrib ...
>
> I tested all contrib functions that take regclass arguments (see
> attached test.sql and test_result.txt). The result shows that only
> pg_prewarm() can lead to the assertion failure.

Right, even while I was searching, I see this is used in 3 contrib
modules, amcheck, autoprewarm, and pg_prewarm. amcheck is already
checking for AM type, and Autoprewarm is identifying the relation by
block, so there is no chance of getting the relation which do not have
storage.

>
> However, I found that amcheck's error messages can be misleading
> when run on partitioned indexes.
>
> For example, on the master branch, amcheck (e.g., bt_index_check
> function)
> shows this error:
>
>   > ERROR:  expected "btree" index as targets for verification
>   > DETAIL:  Relation "pgbench_accounts_pkey" is a btree index.
>
> This message says it expects a "btree" index, yet also states the
> relation
> is a "btree" index, which can seem contradictory. The actual issue is
> that
> the index is a btree partitioned index, but this detail is missing,
> causing
> possible confusion.

Yes, I found the error message confusing during testing as well, so it
makes sense to improve it.

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com