RE: Disable WAL logging to speed up data loading

From: Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)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't care 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