Fujii Masao wrote:
On Wed, Dec 9, 2009 at 6:25 PM, Fujii Masao masao.fu...@gmail.com wrote:
Here is the patch:
- Write an XLOG UNLOGGED record in WAL if WAL-logging is skipped for only
the reason that WAL archiving is not enabled and such record has not been
written yet.
- Cause archive recovery to end if an XLOG UNLOGGED record is found during
it.
Here's an updated version of my New XLOG record indicating WAL-skipping
patch.
http://archives.postgresql.org/pgsql-hackers/2009-12/msg00788.php
Thanks!
I don't like special-casing UNLOGGED records in XLogInsert and
ReadRecord(). Those functions are complicated enough already. The
special handling from XLogInsert() (and a few other places) is only
required because the UNLOGGED records carry no payload. That's easy to
avoid, just add some payload to them, doesn't matter what it is. And I
don't think ReadRecord() is the right place to emit the errors/warnings,
that belongs naturally in xlog_redo().
It might be useful to add some information in the records telling why
WAL-logging was skipped. It might turn out to be useful in debugging.
That also conveniently adds payload to the records, to avoid the
special-casing in XLogInsert() :-).
I think it's a premature optimization to skip writing the records if
we've written in the same session already. Especially with the 'reason'
information added to the records, it's nice to have a record of each
such operation. All operations that skip WAL-logging are heavy enough
that an additional WAL record will make no difference. I can see that it
was required to avoid the flooding from heap_insert(), but we can move
the XLogSkipLogging() call from heap_insert() to heap_sync().
Attached is an updated patch, doing the above. Am I missing anything?
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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