Why checkpoint_timeout had maximum value of 1h?

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От Maxim Boguk
Тема Why checkpoint_timeout had maximum value of 1h?
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Msg-id CAK-MWwR4DDGPLpC2Gw6e7R2+R_GWqfMONcRBj-AyQuqyqZfZHA@mail.gmail.com
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Ответы Re: Why checkpoint_timeout had maximum value of 1h?  (Greg Smith <greg@2ndQuadrant.com>)
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Hi all,

Is there any real reason why checkpoint_timeout limited to 1hour?

In my case I have some replicas with WAL on SAS raid and PGDATA on SSD with limited write endurance.
And I don't worry about possible long time recovery after power failure in that case.
Whats more working dataset fill in shared buffers, so almost no dirty buffers evictions by bgwriter or backends happened.

In that case having checkpoint_timeout=10hour could reduce amout of writes on SSD  by factor of 10, and increase planned ssd lifetime by the same amount.

I would like to have ability to set checkpoint_timeout=high value
and (whats even better) checkpoint_timeout=0 - in that case checkpoint happen when all checkpoint_segments were used.

Is there any serious drawbacks in that idea?

Is it safe to increase that limit in source and rebuild database?  (9.0 and 9.1 case)

--
Maxim Boguk
Senior Postgresql DBA.

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