Bruce Momjian wrote:
Josh Berkus wrote:
Bruce,
We never actually considred undo, but high UPDATE activity was one of
the areas we historically handled poorly compared to undo systems, and
undo would have been one way to improve that area. I think with HOT we
have improved high UPDATE activity enough that the undo benefits are no
longer attractive (and of course the undo disadvantages were never
attractive).
If you're asking if we should remove the TODO (is there one?) and
replace it with a FAQ item called "Why PostgreSQL doesn't have an UNDO
LOG", then my vote is "yes".
No, it never got close to being a TODO item. It was more a limitation
we had that is now fixed.
HOT is cool, but it really doesn't solve the whole problem. It works for
a significant class of problems, but for example it won't have any
significant effect on the app I'm currently working on which is very
index-rich. It would be a major mistake to think there's no work left to
do in improving update performance.
cheers
andrew
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