Re: Checkpoint question - Mailing list pgsql-general

From u15074
Subject Re: Checkpoint question
Date
Msg-id 1058795870.3f1bf15e93e98@webmail.hs-harz.de
Whole thread Raw
In response to Checkpoint question  (u15074 <u15074@hs-harz.de>)
Responses Re: Checkpoint question  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
Zitat von Tom Lane <tgl@sss.pgh.pa.us>:

> A checkpoint pushes out all unwritten data since the last checkpoint.
> So yeah, it stands to reason that if you increase the time between
> checkpoints, each checkpoint will take longer.  Whether this is really
> a problem is not clear --- the checkpoint is happening in background
> after all.  Why should you care how long it takes?
>
>             regards, tom lane
>
>

What I want to do, is to write a lot of data in the database over a longer
period (assume 1 hour or longer) with constant data rates - I am trying to use
Postgres to store measurement data.

When I only had a few checkpoint_segments (3 I think), I always got an
interruption when the database was checkpointing (what took about 3 seconds).
So I increased the checkpoint_segments and the pauses went away.
But now I think if I reach the segments limit again, I will get even bigger
pauses (of course at some point in the time a checkpoint has to be performed).

By the way, if you say, checkpointing is happening in the background, I don't
know what causes the pauses.

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