Re: Use streaming read API in ANALYZE

Hi,

On Mon, 19 Feb 2024 at 18:13, Nazir Bilal Yavuz <byavuz81@gmail.com> wrote:
>
> I worked on using the currently proposed streaming read API [1] in ANALYZE. The patch is attached. 0001 is the not
yetmerged streaming read API code changes that can be applied to the master, 0002 is the actual code.
 
>
> The blocks to analyze are obtained by using the streaming read API now.
>
> - Since streaming read API is already doing prefetch, I removed the #ifdef USE_PREFETCH code from
acquire_sample_rows().
>
> - Changed 'while (BlockSampler_HasMore(&bs))' to 'while (nblocks)' because the prefetch mechanism in the streaming
readAPI will advance 'bs' before returning buffers.
 
>
> - Removed BlockNumber and BufferAccessStrategy from the declaration of scan_analyze_next_block(), passing pgsr
(PgStreamingRead)instead of them.
 
>
> I counted syscalls of analyzing ~5GB table. It can be seen that the patched version did ~1300 less read calls.
>
> Patched:
>
> % time     seconds  usecs/call     calls    errors syscall
> ------ ----------- ----------- --------- --------- ----------------
>  39.67    0.012128           0     29809           pwrite64
>  36.96    0.011299           0     28594           pread64
>  23.24    0.007104           0     27611           fadvise64
>
> Master (21a71648d3):
>
> % time     seconds  usecs/call     calls    errors syscall
> ------ ----------- ----------- --------- --------- ----------------
>  38.94    0.016457           0     29816           pwrite64
>  36.79    0.015549           0     29850           pread64
>  23.91    0.010106           0     29848           fadvise64
>
>
> Any kind of feedback would be appreciated.
>
> [1]:
https://www.postgresql.org/message-id/CA%2BhUKGJkOiOCa%2Bmag4BF%2BzHo7qo%3Do9CFheB8%3Dg6uT5TUm2gkvA%40mail.gmail.com

The new version of the streaming read API [1] is posted. I updated the
streaming read API changes patch (0001), using the streaming read API
in ANALYZE patch (0002) remains the same. This should make it easier
to review as it can be applied on top of master

[1]: https://www.postgresql.org/message-id/CA%2BhUKGJtLyxcAEvLhVUhgD4fMQkOu3PDaj8Qb9SR_UsmzgsBpQ%40mail.gmail.com

--
Regards,
Nazir Bilal Yavuz
Microsoft