From: | Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> |
---|---|
To: | Stephen Frost <sfrost(at)snowman(dot)net>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
Cc: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Jakub Wartak <Jakub(dot)Wartak(at)tomtom(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: automatic analyze: readahead - add "IO read time" log message |
Date: | 2021-03-08 03:26:18 |
Message-ID: | cc0df204-ee35-8ffc-1a5d-988462ec3be0@enterprisedb.com |
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Lists: | pgsql-hackers |
Hi,
On 2/10/21 11:10 PM, Stephen Frost wrote:
> Greetings,
>
> * Heikki Linnakangas (hlinnaka(at)iki(dot)fi) wrote:
>> On 05/02/2021 23:22, Stephen Frost wrote:
>>> Unless there's anything else on this, I'll commit these sometime next
>>> week.
>>
>> One more thing: Instead of using 'effective_io_concurrency' GUC directly,
>> should call get_tablespace_maintenance_io_concurrency().
>
> Ah, yeah, of course.
>
> Updated patch attached.
>
A couple minor comments:
1) I think the patch should be split into two parts, one adding the
track_io_timing, one adding the prefetching.
2) I haven't tried but I'm pretty sure there'll be a compiler warning
about 'prefetch_maximum' being unused without USE_PREFETCH defined.
3) Is there a way to reduce the amount of #ifdef in acquire_sample_rows?
This makes the code rather hard to read, IMHO. It seems to me we can
move the code around a bit and merge some of the #ifdef blocks - see the
attached patch. Most of this is fairly trivial, with the exception of
moving PrefetchBuffer before table_scan_analyze_next_block - AFAIK this
does not materially change the behavior, but perhaps I'm wrong.
regards
--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
Attachment | Content-Type | Size |
---|---|---|
analyze_prefetch_v7.patch | text/x-patch | 10.8 KB |
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