Re: CREATE INDEX and HOT (was Question:pg_classattributes and race conditions ?) - Mailing list pgsql-hackers

From Pavan Deolasee
Subject Re: CREATE INDEX and HOT (was Question:pg_classattributes and race conditions ?)
Date
Msg-id 45FE67AF.6060003@enterprisedb.com
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In response to Re: CREATE INDEX and HOT (was Question:pg_classattributes and race conditions ?)  ("Simon Riggs" <simon@2ndquadrant.com>)
Responses Re: CREATE INDEX and HOT (was Question:pg_classattributes and race conditions ?)  ("Simon Riggs" <simon@2ndquadrant.com>)
List pgsql-hackers
Simon Riggs wrote:>> This problem is solved by moving the wait (for all transactions in> reference snapshot to finish)
sothat it is now between the first and> second scans, as described.>> During the second Vscan we would prune each
block,so the only remaining> tuple in the block when the second scan sees it would be (10,30) and it> would no longer
bea HOT tuple - the index would have a pointer to it,> so no new index pointer would be added. The pointer to (10,30)
isthe> same pointer that was added in the first phase for the tuple (10,20).>
 

The problem is that in the first phase, the pointer was inserted
with key=20 whereas now its changed to 30. So we need to delete the old
index entry and add a new one.

Thanks,
Pavan


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