Horton

Re: Table AM Interface Enhancements

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Pavel Borisov <pashkin.elfe@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Alexander Korotkov <aekorotkov@gmail.com>, Melanie Plageman <melanieplageman@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: 2024-04-15T19:47:52Z
Lists: pgsql-hackers 
Hi,

On 2024-04-15 23:14:01 +0400, Pavel Borisov wrote:
> Why it makes a difference looks a little bit unclear to me, I can't comment
> on this. I noticed that before 041b96802ef we had a block number and block
> sampler state that tied acquire_sample_rows() to the actual block
> structure.

That, and the prefetch calls actually translating the block numbers 1:1 to
physical locations within the underlying file.

And before 041b96802ef they were tied much more closely by the direct calls to
heapam added in 27bc1772fc81.


> After we have the whole struct ReadStream which doesn't comprise just a
> wrapper for the same variables, but the state that ties
> acquire_sample_rows() to the streaming read algorithm (and heap).

Yes ... ? I don't see how that is a meaningful difference to the state as of
27bc1772fc81.  Nor fundamentally worse than the state 27bc1772fc81^, given
that we already issued requests for specific blocks in the file.

That said, I don't like the state after applying
https://postgr.es/m/CAPpHfdvuT6DnguzaV-M1UQ2whYGDojaNU%3D-%3DiHc0A7qo9HBEJw%40mail.gmail.com
because there's too much coupling. Hence talking about needing to iterate on
the interface in some form, earlier in the thread.


What are you actually arguing for here?

Greetings,

Andres Freund

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