Re: CREATE INDEX and HOT - revised design

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