From: | "Simon Riggs" <simon(at)2ndquadrant(dot)com> |
---|---|
To: | "Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)com> |
Cc: | "Bruce Momjian" <bruce(at)momjian(dot)us>, "PostgreSQL-development" <pgsql-hackers(at)postgresql(dot)org>, "Pavan Deolasee" <pavan(dot)deolasee(at)enterprisedb(dot)com>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Subject: | Re: CREATE INDEX and HOT - revised design |
Date: | 2007-03-28 17:12:52 |
Message-ID: | 1175101972.4386.408.camel@silverbirch.site |
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Lists: | pgsql-hackers |
On Wed, 2007-03-28 at 22:24 +0530, Pavan Deolasee wrote:
> Just when I thought we have nailed down CREATE INDEX, I realized
> that there something more to worry. The problem is with the HOT-chains
> created by our own transaction which is creating the index. We thought
> it will be enough to index the tuple at the head-of-the-chain since
> that
> would be the visible copy once the transaction commits. We thought
> of keeping the index unavailable for queries in pre-existing
> transactions
> by setting a new "xid" attribute in pg_index. The question is what
> value
> to assign to "xid". I though we would assign ReadNewTransactionId().
> Any idea how to handle this case ?
Set it at the end, not the beginning.
If you are indexing a table that hasn't just been created by you, set
the xcreate field on pg_index at the *end* of the build using
ReadNewTransactionId(). Any xid less than that sees the index as
invalid. If you created the table in this transaction (i.e.
createSubId != 0) then set xcreate to creating xid.
--
Simon Riggs
EnterpriseDB http://www.enterprisedb.com
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