From: | Aidan Van Dyk <aidan(at)highrise(dot)ca> |
---|---|
To: | "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Brian Hurt <bhurt(at)janestcapital(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Block-level CRC checks |
Date: | 2008-10-02 16:51:01 |
Message-ID: | 20081002165101.GZ16893@yugib.highrise.ca |
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Lists: | pgsql-hackers |
* Jonah H. Harris <jonah(dot)harris(at)gmail(dot)com> [081002 12:43]:
> > #define write(fd, buf, count) buffer_crc_write(fd, buf, count)
>
> I certainly wouldn't interpose the write() call itself; that's just
> asking for trouble.
Of course not, that was only to show that whatever you currenlty pritect
"write()" with, is valid for protecting the buffer+write.
> > But I thought you didn't really care about hint-bit updates, even in the
> > current strategy... but I'm fully ignorant about the code, sorry...
>
> The current implementation does not take it into account.
So if PG currently doesn't care about the hit-bits being updated, during
the write, then why should introducing a double-buffer introduce the a
torn-page problem Tom mentions? I admit, I'm fishing for information
from those in the know, because I haven't been looking at the code long
enough (or all of it enough) to to know all the ins-and-outs...
a.
--
Aidan Van Dyk Create like a god,
aidan(at)highrise(dot)ca command like a king,
http://www.highrise.ca/ work like a slave.
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