Re: [PING] [PATCH v2] parallel pg_restore: avoid disk seeks when jumping short distance forward
Dimitrios Apostolou <jimis@gmx.net>
From: Dimitrios Apostolou <jimis@gmx.net>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@lists.postgresql.org
Date: 2025-06-14T16:01:13Z
Lists: pgsql-hackers
On Fri, 13 Jun 2025, Nathan Bossart wrote: > 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? read(4, "..."..., 8192) = 8192 read(4, "..."..., 4096) = 4096 read(4, "..."..., 12288) = 12288 read(4, "..."..., 4096) = 4096 read(4, "..."..., 8192) = 8192 read(4, "..."..., 4096) = 4096 read(4, "..."..., 8192) = 8192 read(4, "..."..., 4096) = 4096 read(4, "..."..., 8192) = 8192 read(4, "..."..., 4096) = 4096 read(4, "..."..., 8192) = 8192 read(4, "..."..., 4096) = 4096 read(4, "..."..., 8192) = 8192 read(4, "..."..., 4096) = 4096 read(4, "..."..., 8192) = 8192 read(4, "..."..., 4096) = 4096 read(4, "..."..., 12288) = 12288 read(4, "..."..., 4096) = 4096 read(4, "..."..., 8192) = 8192 read(4, "..."..., 4096) = 4096 read(4, "..."..., 12288) = 12288 read(4, "..."..., 4096) = 4096 read(4, "..."..., 8192) = 8192 read(4, "..."..., 4096) = 4096 read(4, "..."..., 8192) = 8192 read(4, "..."..., 4096) = 4096 read(4, "..."..., 12288) = 12288 read(4, "..."..., 4096) = 4096 read(4, "..."..., 8192) = 8192 read(4, "..."..., 4096) = 4096
Commits
-
Avoid short seeks in pg_restore.
- fba60a1b107d 19 (unreleased) landed
-
Don't rely on zlib's gzgetc() macro.
- 277dec651472 19 (unreleased) cited
-
Add more TAP test coverage for pg_dump.
- 20ec9958921a 19 (unreleased) landed
-
Split 002_pg_dump.pl into two test files.
- 9dcf7f1172cd 19 (unreleased) landed
-
Align the data block sizes of pg_dump's various compression modes.
- 66ec01dc4124 19 (unreleased) landed
-
Fix serious performance problems in LZ4Stream_read_internal.
- 1f8062dd9668 19 (unreleased) landed
-
Fix poor buffering logic in pg_dump's lz4 and zstd compression code.
- fe8192a95e6c 19 (unreleased) landed
-
Fix issue with reading zero bytes in Gzip_read.
- bf18e9bd70de 17.7 landed
- a239c4a0c226 19 (unreleased) landed
- 6a4009747c36 18.1 landed
- 1518b7d76aad 16.11 landed
-
Restore test coverage of LZ4Stream_gets().
- eac2b1697d48 17.7 landed
- 661b320ed4e0 18.1 landed
- 26d1cd375f15 19 (unreleased) landed