Stefan Kaltenbrunner wrote:
Heikki Linnakangas wrote:
2. Pointer swinging. At the moment, after a row is HOT updated, the only
way to get rid of the redirecting line pointer is to run VACUUM FULL or
CLUSTER (or delete or cold update the row and vacuum). If we want to
implement pointer swinging before release, we have to get started now.
If we're happy to release without it and address the issue in later
releases if it seems important, we need to make a conscious decision on
that, now. I personally think we can release without it.
hmm - I don't really understand most of the stuff behind HOT but does
this mean that VACUUM FULL (or CLUSTER) is becoming a recommended or
even required routine maintenance task for people using HOT ?
No more than before. See the comment "or delete or cold update the row and vacuum". The row couldn't be cleared by vacuum before unless delete/update. Based on the above, it appears that every time an HOT update occurs, 4 to 8 bytes might get wasted in the page. Eventually this fills the page and a regular cold update is required and it is cleared.



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