Re: pgBufferUsage.blk_{read|write}_time are zero although there are pgBufferUsage.local_blks_{read|written}

Nazir Bilal Yavuz <byavuz81@gmail.com>

From: Nazir Bilal Yavuz <byavuz81@gmail.com>

To: Melanie Plageman <melanieplageman@gmail.com>

Cc: pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2023-10-03T09:37:37Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Fix description of I/O timing info for shared buffers in EXPLAIN (BUFFERS)
- 8dd70828b460 15.6 landed
- db69101a1d00 16.2 landed
pg_stat_statements: Add local_blk_{read|write}_time
- 5147ab1dd34a 17.0 landed
Add local_blk_{read|write}_time I/O timing statistics for local blocks
- 295c36c0c1fa 17.0 landed
Rename I/O timing statistics columns to shared_blk_{read|write}_time
- 13d00729d422 17.0 landed
Count write times when extending relation files for shared buffers
- 2308f18c0733 16.1 landed
- d17ffc734dad 17.0 landed
Add JIT deform_counter
- 5a3423ad8ee1 17.0 cited

Attachments

v2-0002-PG16-Add-pgBufferUsage.blk_write_time-to-for-IOOp.patch (application/x-patch) patch v2-0002
v2-0001-PG16-Increase-pgBufferUsage.blk_-read-write-_time.patch (application/x-patch) patch v2-0001
v2-0002-PG15-Add-pgBufferUsage.blk_write_time-to-for-exte.patch (text/x-diff) patch v2-0002
v2-0001-PG15-Add-pgBufferUsage.blk_write_time-to-for-loca.patch (text/x-diff) patch v2-0001

Hi,

On Fri, 15 Sept 2023 at 16:30, Melanie Plageman
<melanieplageman@gmail.com> wrote:
>
> Yes, good catch. This is a bug. I will note that at least in 15 and
> likely before, pgBufferUsage.local_blks_written is incremented for
> local buffers but pgBufferUsage.blk_write_time is only added to for
> shared buffers (in FlushBuffer()). I think it makes sense to propose a
> bug fix to stable branches counting blk_write_time for local buffers
> as well.

I attached the PG16+ (after pg_stat_io) and PG15- (before pg_stat_io)
versions of the same patch.

Regards,
Nazir Bilal Yavuz
Microsoft