>On further review, I think that we ought to make MarkBufferDirty() the
>caller's job, because sometimes we may need to xlog only if
>XLogIsNeeded(), but the buffer's got to get marked dirty either way.
Incase the place where Xlog is not required, woudn't it fsync the data;
So in that case even MarkBufferDirty() will also be not required.
>So I think the new function should just do step 5 - emit XLOG and set
>LSN/TLI.
In the API log_newpage_buffer(), as buffer already contains the page to be logged, so can't it be assumed that the page
willbe initialized and no need to check
if PageIsNew before setting LSN/TLI.
________________________________________
From: pgsql-hackers-owner@postgresql.org [pgsql-hackers-owner@postgresql.org] on behalf of Robert Haas
[robertmhaas@gmail.com]
Sent: Friday, June 08, 2012 10:50 PM
To: Tom Lane
Cc: pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] log_newpage header comment
On Fri, Jun 8, 2012 at 9:56 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> OK. So what I'm thinking is that we should add a new function that
> takes a relfilenode and a buffer and steps 4-6 of what's described in
> transam/README: mark the buffer dirty, xlog it, and set the LSN and
> TLI. We might want to have this function assert that it is in a
> critical section, for the avoidance of error. Then anyone who wants
> to use it can do steps 1-3, call the function, and then finish up with
> steps 6-7. I don't think we can cleanly encapsulate any more than
> that.
On further review, I think that we ought to make MarkBufferDirty() the
caller's job, because sometimes we may need to xlog only if
XLogIsNeeded(), but the buffer's got to get marked dirty either way.
So I think the new function should just do step 5 - emit XLOG and set
LSN/TLI.
Proposed patch attached.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
