Horton

Re: Table AM Interface Enhancements

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Alexander Korotkov <aekorotkov@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Pavel Borisov <pashkin.elfe@gmail.com>, Japin Li <japinli@hotmail.com>, Mark Dilger <mark.dilger@enterprisedb.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Michael Paquier <michael@paquier.xyz>, Heikki Linnakangas <hlinnaka@iki.fi>, Thomas Munro <thomas.munro@gmail.com>, Nazir Bilal Yavuz <byavuz81@gmail.com>
Date: 2024-04-10T21:21:17Z
Lists: pgsql-hackers 
Hi,

On 2024-04-10 16:50:44 -0400, Melanie Plageman wrote:
> This brings up a question about the prefetching. We never had to have
> this discussion for sequential scan streaming read because it didn't
> (and still doesn't) do prefetching. But, if we push the streaming read
> code down into the heap AM layer, it will be doing the prefetching.
> So, do we remove the prefetching from acquire_sample_rows() and expect
> other table AMs to implement it themselves or use the streaming read
> API?

The prefetching added to acquire_sample_rows was quite narrowly tailored to
something heap-like - it pretty much required that block numbers to be 1:1
with the actual physical on-disk location for the specific AM.  So I think
it's pretty much required for this to be pushed down.

Using a read stream is a few lines for something like this, so I'm not worried
about it. I guess we could have a default implementation for block based AMs,
similar what we have around table_block_parallelscan_*, but not sure it's
worth doing that, the complexity is much lower than in the
table_block_parallelscan_ case.

Greetings,

Andres

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