From: Mikkel Lauritsen <renard@tala.dk>
To: David Rowley <dgrowleyml@gmail.com>
Cc: pgsql-performance <pgsql-performance@postgresql.org>
Subject: Re: Windows slowness?
Date: Thu, 11 Jun 2020 07:05:50 +0200
Message-ID: <9c05b2302f277afd0ced7e74a96ca5a7@tala.dk> (raw)
In-Reply-To: <CAApHDvp5Jn6ZWgSogKhS3skCmCmJ4rb-jAPktek03dcpD3QHaA@mail.gmail.com>
References: <db3f5345af6b95330b2a51fbebbb0f02@tala.dk>
<CAApHDvp5Jn6ZWgSogKhS3skCmCmJ4rb-jAPktek03dcpD3QHaA@mail.gmail.com>
Hi David,
Many thanks for your response - you wrote:
On 2020-06-10 23:08, David Rowley wrote:
> On Thu, 11 Jun 2020 at 07:41, Mikkel Lauritsen <renard@tala.dk> wrote:
>> I have a query that runs much slower in Postgres on Windows than on
>> Linux
>
>> Using explain analyze on the database running on Windows I get
>>
>> -> Index Scan using event_pkey on event t1 (cost=0.56..0.95 rows=1
>> width=295) (actual time=0.075..0.075 rows=0 loops=229227)
>
>> If I copy the database to my laptop running Linux (Postgres 12 on
>> Fedora
>> 32, i7-9750H, 16 GB ram) I get the exact same execution plan. Explain
>> analyze says
>>
>> -> Index Scan using event_pkey on event t1 (cost=0.56..0.95 rows=1
>> width=295) (actual time=0.008..0.008 rows=0 loops=229227)
--- snip ---
> Can you confirm what: SELECT pg_relation_size('event_pkey'),
> pg_relation_size('event'); says on each
1011384320 and 2753077248, respectively.
--- snip ---
> It would be good to see:
>
> SET track_io_timing = on;
> EXPLAIN (ANALYZE, BUFFERS) <the query>
I wasn't aware of that tracing option - thanks! For this particular plan
entry the output is
Buffers: shared hit=896304 read=257234
I/O Timings: read=11426.745
Some rows have been added to the table since my initial mail, so the
numbers may be slightly off.
As another reply has suggested I need to verify that somebody hasn't
accidentally misconfigured an antivirus client to scan the database
files. If that turns out to be the case I guess it's embarrassment of
the year for me :-/
Best regards,
Mikkel Lauritsen
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To: pgsql-performance@postgresql.org
Cc: renard@tala.dk, dgrowleyml@gmail.com
Subject: Re: Windows slowness?
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