On 4/19/07, Heikki Linnakangas <[EMAIL PROTECTED]> wrote:



What's the purpose of the "HeapScanHintPagePrune" mechanism in index
builds? I lost track of the discussion on create index, is the it
necessary for correctness?


Its not required strictly for correctness, but it helps us prune the
HOT-chains
while index building. During index build, if we skip a tuple which is
RECENTLY_DEAD, existing transactions can not use the index for queries.
Pruning the HOT-chains reduces the possibility of finding such tuples
while building the index.


A comment in IndexBuildHeapScan explaining
why it's done would be nice.


I would do that.


In any case a PG_TRY/CATCH block should be
used to make sure it's turned off after an unsuccessful index build.


Oh thanks. Would do that too

I would wait for other review comments before submitting a fresh patch.
I hope thats ok.

Thanks,
Pavan
--

EnterpriseDB     http://www.enterprisedb.com

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