Re: Will modifications to unlogged tables also be flused to disk? - Mailing list pgsql-general

From Clemens Eisserer
Subject Re: Will modifications to unlogged tables also be flused to disk?
Date
Msg-id CAFvQSYTcbv5TpC1Q8JMCG5sh6eZmDVoyL9qQ3PTW0DTzsYwMzA@mail.gmail.com
Whole thread Raw
In response to Re: Will modifications to unlogged tables also be flused to disk?  (Vik Fearing <vik.fearing@dalibo.com>)
Responses Re: Will modifications to unlogged tables also be flused to disk?  (Luca Ferrari <fluca1978@infinito.it>)
List pgsql-general
Hi Vik,

> Yes.  The only difference between logged and unlogged tables is the lack
> of WAL.  As long as there's no crash, unlogged tables are treated the
> same as logged tables as far as flushing/fsync-ing is concerned.

Ok thats really bad news :/
After reading the discussion about calling unlogged tables "in memory"
or "cached" I actually had high hopes pgql would take advantage of the
fact that data of unlogged tables are not preserved at recovery.

However, it seems pgsql fsyncs frequently to guarantee durability of
table data which will be rejected anyway at recovery from an unclean
shutdown.

I'll have a look at the source and probably prepare a patch.

Regards, Clemens


pgsql-general by date:

Previous
From: Vik Fearing
Date:
Subject: Re: Will modifications to unlogged tables also be flused to disk?
Next
From: Andres Freund
Date:
Subject: Re: Will modifications to unlogged tables also be flused to disk?