Simon Riggs wrote:
On Sun, 2007-06-17 at 08:51 +0100, Heikki Linnakangas wrote:
Do we need to know it so exactly that we look
at WALInsertLock? Maybe use info_lck to request the latest page, since
that is less heavily contended and we need never wait across I/O.
Is there such a value available, that's protected by just info_lck? I can't see one.

XLogCtl->LogwrtRqst.Write

That's the Write location. checkpoint_segments is calculated against the Insert location. In a normal OLTP scenario they would be close to each other, but if you're doing a huge data load in a transaction; restoring from backup for example, they could be really far apart.

--
  Heikki Linnakangas
  EnterpriseDB   http://www.enterprisedb.com

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