| From: | "Pavan Deolasee" <pavan(dot)deolasee(at)enterprisedb(dot)com> |
|---|---|
| To: | "Simon Riggs" <simon(at)2ndquadrant(dot)com> |
| Cc: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, <pgsql-hackers(at)postgresql(dot)org>, "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com> |
| Subject: | Re: CREATE INDEX and HOT (was Question:pg_classattributes and race conditions ?) |
| Date: | 2007-03-19 10:36:31 |
| Message-ID: | 45FE67AF.6060003@enterprisedb.com |
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| Lists: | pgsql-hackers |
Simon Riggs wrote:
>
> This problem is solved by moving the wait (for all transactions in
> reference snapshot to finish) so that 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 be a HOT tuple - the index would have a pointer to it,
> so no new index pointer would be added. The pointer to (10,30) is the
> 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
--
EnterpriseDB http://www.enterprisedb.com
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