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