On 13.12.2010 19:48, Tom Lane wrote:
Heikki Linnakangas<heikki.linnakan...@enterprisedb.com> writes:
On 13.12.2010 19:19, Greg Stark wrote:
If it's only the backup blocks that matter couldn't you generate noop
WAL records with just the full page image in them. Once all those are
generated then generate the actual split operation and since all the
pages have been written to wal since the last checkpoint they won't
need any backup block slots.
This would require surpressing any checkpoints between writing the
first backup block and the final operation record. That might be
pretty hard to do cleanly.
That would work, but it brings us back to square one
Yeah. Wouldn't the original page-split record have been carrying full
page images already?
Yes.
BTW, the original split record doesn't run into the limit because it
doesn't use the backup-block mechanism, it contains all the tuples for
all the pages in the main payload.
(And if so, why didn't we have this problem in the
previous implementation?)
In the previous implementation, the NSN was updated immediately in the
page split record, and there was no follow-right flag to clear. So the
child pages didn't need to be updated when the downlinks are inserted.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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