Jeff Davis wrote:
> 1. In CheckForSerializableConflictIn(), I think the comment above
> may be out of date. It says:
> 2. Also in the comment above CheckForSerializableConflictIn(), I
> see:
> 3. The comment above CheckForSerializableConflictOut() seems to
> trail off, as though you may have meant to write more. It also
> seems to be out of date.
Will fix and post a patch version 15, along with the other fixes
based on feedback to v14 (mostly to comments and docs) within a few
hours.
I'll also do that global change from using "tran" as an abbreviation
for transaction in some places to consistently using xact whenever it
is abbreviated.
> And why are you reading the infomask directly? Do the existing
> visibility functions not suffice?
It's possible we re-invented some code somewhere, but I'm not clear
on what code from this patch might use what existing function. Could
you provide specifics?
> I have made it through predicate.c, and I have a much better
> understanding of what it's actually doing. I can't claim that I
> have a clear understanding of everything involved, but the code
> looks like it's in good shape (given the complexity involved) and
> well-commented.
Thanks! I know that's a lot of work, and I appreciate you pointing
out where comments have not kept up with coding.
> I am marking the patch Ready For Committer, because any committer
> will need time to go through the patch; and the authors have
> clearly applied the thought, care, and testing required for
> something of this complexity. I will continue to work on it,
> though.
Thanks!
> The biggest issue on my mind is what to do about Hot Standby. The
> authors have a plan, but there is also some resistance to it:
>
>
http://archives.postgresql.org/message-id/23698.1295566621@sss.pgh.pa.us
>
> We don't need a perfect solution for 9.1, but it would be nice if
> we had a viable plan for 9.2.
I don't recall any real opposition to what I sketched out in this
post, which came after the above-referenced one:
http://archives.postgresql.org/message-id/4D39D5EC0200002500039A19@gw.wicourts.gov
Also, that opposition appears to be based on a misunderstanding of
the first alternative, which was for sending at most one snapshot per
commit or rollback of a serializable read write transaction, with
possible throttling. The alternative needs at most two bits per
commit or rollback of a serializable read write transaction; although
I haven't checked whether that can be scared up without adding a
whole byte. Read only transactions have nothing to do with the
traffic under either alternative.
-Kevin
