| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, pgsql-hackers(at)postgresql(dot)org, heikki(dot)linnakangas(at)enterprisedb(dot)com, masao(dot)fujii(at)gmail(dot)com |
| Subject: | Re: Checkpointer on hot standby runs without looking checkpoint_segments |
| Date: | 2012-06-08 13:58:23 |
| Message-ID: | CA+U5nM+TaMkLfuwmtELc9As8DS-G3QBYKCF8MNT=ETAPqs0kdQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 8 June 2012 14:47, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> ISTM that we should avoid triggering a checkpoint on the master if
>> checkpoint_segments is less than wal_keep_segments. Such checkpoints
>> serve no purpose because we don't actually limit and recycle the WAL
>> files and all it does is slow people down.
>
> On the other hand, I emphatically disagree with this, for the same
> reasons as on the other thread. Getting data down to disk provides a
> greater measure of safety than having it in memory. Making
> checkpoint_segments not force a checkpoint is no better than making
> checkpoint_timeout not force a checkpoint.
Not sure which bit you are disagreeing with. I have no suggested
change to checkpoint_timeout.
What I'm saying is that forcing a checkpoint to save space, when we
aren't going to save space, makes no sense.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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