RE: Disable WAL logging to speed up data loading - Mailing list pgsql-hackers

From tsunakawa.takay@fujitsu.com
Subject RE: Disable WAL logging to speed up data loading
Date
Msg-id TYAPR01MB2990A8C9DF28E2EC19C70BECFEA80@TYAPR01MB2990.jpnprd01.prod.outlook.com
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In response to Re: Disable WAL logging to speed up data loading  (Kyotaro Horiguchi <horikyota.ntt@gmail.com>)
Responses RE: Disable WAL logging to speed up data loading  ("osumi.takamichi@fujitsu.com" <osumi.takamichi@fujitsu.com>)
List pgsql-hackers
From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
> >     XLogSetRecordFlags(XLOG_MARK_UNIMPORTANT |
> XLOG_MARK_ESSENTIAL);
> >     XLogRegisterData((char *) &dummy, sizeof(dummy));
> >
> > (Here's a word play - unimportant but essential, what's that?)
>
> Hmm. Food may not be important to someone but it is essential for
> survival.  I think this is somethig like that :p

Ah, that's a good answer.  I know a person around me who enjoys drinking alcohol but doesn't enjoy eating - he says he
doesn'tcare about taste of food.  So food is unimportant but nutrition is essential for him. 


> Unfortunately, I prefer the latter as it is simple because it is in a
> hot path.  As I think I mentioned upthread, I think the xlog stuff
> should refrain from being conscious of things deeper than RMger-ID
> level.  One of other reasons is that generally the issuer site is the
> authoritative about the importance and essentiality of a record being
> issued.  And I don't think it's very good to do the same thing in
> different ways at the same time.  Fortunately each type of the recrods
> has only few issuer places.

Agreed.


> By the way, I noticed that pg_switch_wal() silently skips its
> task. Desn't it need to give any sort of ERROR?

Osumi-san, can you check this?  (I thought we were aware of this according to Fujii-san's comment.)


Regards
Takayuki Tsunakawa




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