Horton

Re: Table AM Interface Enhancements

Alexander Korotkov <aekorotkov@gmail.com>

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From: Alexander Korotkov <aekorotkov@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andrei Lepikhov <a.lepikhov@postgrespro.ru>, Pavel Borisov <pashkin.elfe@gmail.com>, Japin Li <japinli@hotmail.com>, Mark Dilger <mark.dilger@enterprisedb.com>, pgsql-hackers@lists.postgresql.org
Date: 2024-04-01T16:48:08Z
Lists: pgsql-hackers 
On Mon, Apr 1, 2024 at 7:36 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> Coverity complained about what you did in RelationParseRelOptions
> in c95c25f9a:
>
> *** CID 1595992:  Null pointer dereferences  (FORWARD_NULL)
> /srv/coverity/git/pgsql-git/postgresql/src/backend/utils/cache/relcache.c: 499 in RelationParseRelOptions()
> 493
> 494             /*
> 495              * Fetch reloptions from tuple; have to use a hardwired descriptor because
> 496              * we might not have any other for pg_class yet (consider executing this
> 497              * code for pg_class itself)
> 498              */
> >>>     CID 1595992:  Null pointer dereferences  (FORWARD_NULL)
> >>>     Passing null pointer "tableam" to "extractRelOptions", which dereferences it.
> 499             options = extractRelOptions(tuple, GetPgClassDescriptor(),
> 500                                                                     tableam, amoptsfn);
> 501
>
> I see that extractRelOptions only uses the tableam argument for some
> relkinds, and RelationParseRelOptions does set it up for those
> relkinds --- but Coverity's complaint isn't without merit, because
> those two switch statements are looking at *different copies of the
> relkind*, which in theory could be different.  This all seems quite
> messy and poorly factored.  Can't we do better?  Why do we need to
> involve two copies of allegedly the same pg_class tuple, anyhow?

Thank you for reporting this, Tom.
I'm planning to investigate this later today.

------
Regards,
Alexander Korotkov

Commits

  1. Remove extra comment at TableAmRoutine.scan_analyze_next_block

  2. revert: Generalize relation analyze in table AM interface

  3. Revert: Allow table AM to store complex data structures in rd_amcache

  4. Revert: Allow table AM tuple_insert() method to return the different slot

  5. Revert: Allow locking updated tuples in tuple_update() and tuple_delete()

  6. Revert: Let table AM insertion methods control index insertion

  7. Revert: Custom reloptions for table AM

  8. Provide a way block-level table AMs could re-use acquire_sample_rows()

  9. Custom reloptions for table AM

  10. Use streaming I/O in ANALYZE.

  11. Revert "Custom reloptions for table AM"

  12. Let table AM insertion methods control index insertion

  13. Generalize relation analyze in table AM interface

  14. Improve error message for tts_(virtual|minimal)_is_current_xact_tuple

  15. Add comments on some MinimalTupleSlots methods usage

  16. Add TupleTableSlotOps.is_current_xact_tuple() method

  17. Allow table AM tuple_insert() method to return the different slot

  18. Allow table AM to store complex data structures in rd_amcache