On Tue, Jul 8, 2014 at 1:06 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Andres Freund <andres@2ndquadrant.com> writes:
>> On 2014-07-07 09:57:20 -0400, Tom Lane wrote:
>>> Well, see the comment that explains why the logic is like this now:
>
>> I think we should 'simply' make sequences assign a toplevel xid - then
>> we can get rid of that special case in RecordTransactionCommit(). And I
>> think the performance benefit of not having to wait on XLogFlush() for
>> readonly xacts due to hot prunes far outweighs the decrease due to the
>> xid assignment/commit record. I don't think that nextval()s are called
>> overly much without a later xid assigning statement.
>
> Yeah, that could well be true. I'm not sure if there are any other cases
> where we have non-xid-assigning operations that are considered part of
> what has to be flushed before reporting commit;
Maybe pg_switch_xlog().
> if there are not, I'd
> be okay with changing nextval() this way.
+1
Regards,
--
Fujii Masao