Horton

Re: [PING] [PATCH v2] parallel pg_restore: avoid disk seeks when jumping short distance forward

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Dimitrios Apostolou <jimis@gmx.net>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@lists.postgresql.org
Date: 2025-06-13T22:04:47Z
Lists: pgsql-hackers 
On Fri, Jun 13, 2025 at 01:00:26AM +0200, Dimitrios Apostolou wrote:
> By the way, I might have set the threshold to 1MB in my program, but
> lowering it won't show a difference in my test case, since the lseek()s I
> was noticing before the patch were mostly 8-16KB forward. Not sure what is
> the defining factor for that. Maybe the compression algorithm, or how wide
> the table is?

I may have missed it, but could you share what the strace looks like with
the patch applied?

-- 
nathan

Commits

  1. Avoid short seeks in pg_restore.

  2. Don't rely on zlib's gzgetc() macro.

  3. Add more TAP test coverage for pg_dump.

  4. Split 002_pg_dump.pl into two test files.

  5. Align the data block sizes of pg_dump's various compression modes.

  6. Fix serious performance problems in LZ4Stream_read_internal.

  7. Fix poor buffering logic in pg_dump's lz4 and zstd compression code.

  8. Fix issue with reading zero bytes in Gzip_read.

  9. Restore test coverage of LZ4Stream_gets().