Horton

Re: XID formatting and SLRU refactorings (was: Add 64-bit XIDs into PostgreSQL 15)

Noah Misch <noah@leadboat.com>

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From: Noah Misch <noah@leadboat.com>
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Maxim Orlov <orlovmg@gmail.com>, Aleksander Alekseev <aleksander@timescale.com>, Postgres hackers <pgsql-hackers@lists.postgresql.org>, Heikki Linnakangas <hlinnaka@iki.fi>, Japin Li <japinli@hotmail.com>, Andres Freund <andres@anarazel.de>, Michael Paquier <michael@paquier.xyz>, Pavel Borisov <pashkin.elfe@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Date: 2024-06-26T00:27:47Z
Lists: pgsql-hackers 
On Mon, Nov 27, 2023 at 01:43:26AM +0200, Alexander Korotkov wrote:
> v61 looks good to me.  I'm going to push it as long as there are no objections.

This yielded commit 4ed8f09 "Index SLRUs by 64-bit integers rather than by
32-bit integers" and left some expressions coercing SLRU page numbers to int.
Two sources:

  grep -i 'int\b.*page' $(git grep -l SimpleLruInit)
  make && touch $(git grep -l SimpleLruInit) && make PROFILE=-Wconversion 2>&1 | less -p '.int. from .int64. may alter its value'

(Not every match needs to change.)

> --- a/src/include/access/slru.h
> +++ b/src/include/access/slru.h

> @@ -127,7 +127,15 @@ typedef struct SlruCtlData
>  	 * the behavior of this callback has no functional implications.)  Use
>  	 * SlruPagePrecedesUnitTests() in SLRUs meeting its criteria.
>  	 */
> -	bool		(*PagePrecedes) (int, int);
> +	bool		(*PagePrecedes) (int64, int64);
> +
> +	/*
> +	 * If true, use long segment filenames formed from lower 48 bits of the
> +	 * segment number, e.g. pg_xact/000000001234. Otherwise, use short
> +	 * filenames formed from lower 16 bits of the segment number e.g.
> +	 * pg_xact/1234.
> +	 */
> +	bool		long_segment_names;

SlruFileName() makes 15-character (60-bit) file names.  Where does the 48-bit
limit arise?  How does the SlruFileName() comment about a 24-bit limit for
short names relate this comment's 16-bit limit?

nm

Commits

  1. Fix more holes with SLRU code in need of int64 for segment numbers

  2. Use more consistently int64 for page numbers in SLRU-related code

  3. Improve comments in slru.{c,h} about segment name format

  4. Reorder actions in ProcArrayApplyRecoveryInfo()

  5. Fix typo in 5a1dfde8334b

  6. Fix warning due non-standard inline declaration in 4ed8f0913bfdb5f355

  7. Add SLRU tests for 64-bit page case

  8. Make use FullTransactionId in 2PC filenames

  9. Use larger segment file names for pg_notify

  10. Index SLRUs by 64-bit integers rather than by 32-bit integers

  11. Keep track of transaction commit timestamps

  12. Handle 5-char filenames in SlruScanDirectory