Re: checkpoints taking much longer than expected - Mailing list pgsql-general

From Jeff Janes
Subject Re: checkpoints taking much longer than expected
Date
Msg-id CAMkU=1w2dboWLEtv9iy+LvmDTceQ+qNTf4puqn4H5TsGS8yWyQ@mail.gmail.com
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In response to Re: checkpoints taking much longer than expected  (Tiemen Ruiten <t.ruiten@tech-lab.io>)
Responses Re: checkpoints taking much longer than expected
Re: checkpoints taking much longer than expected
List pgsql-general
On Sat, Jun 15, 2019 at 4:50 AM Tiemen Ruiten <t.ruiten@tech-lab.io> wrote:

On Fri, Jun 14, 2019 at 5:43 PM Stephen Frost <sfrost@snowman.net> wrote:

The time information is all there and it tells you what it's doing and
how much had to be done... If you're unhappy with how long it takes to
write out gigabytes of data and fsync hundreds of files, talk to your
storage people...

Right, but true only because they were "checkpoint starting: immediate".  Otherwise the reported write time includes intentional sleeps added to honor the checkpoint_completion_target.  A bit confusing to report it that way, I think.

I am the storage people too :)

So, what did you say to yourself?  Have you done fundamental benchmarking at the OS level, to see how fast you can write out 1-2 GB of data changes spread out randomly over a few hundred GB of data, when it is not coming from PostgreSQL?

Cheers,

Jeff

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