Simon Riggs wrote:
On Mon, 2007-03-12 at 13:56 -0400, Tom Lane wrote:
At this point I'm feeling unconvinced that we want it at all. It's
sounding like a large increase in complexity (both implementation-wise
and in terms of API ugliness) for a fairly narrow use-case --- just
how much territory is going to be left for this between HOT and bitmap
indexes?
HOT and clustered indexes have considerable synergy. In many tests we've
got +20% performance with them acting together. Neither one achieves
this performance on their own, but together they work very well.
To clarify, Simon is talking about DBT-2 tests we run in November.
Clustered indexes don't require HOT per se, but on TPC-C the performance
benefit comes from reducing the amount of I/O on the stock table and
index, and that's a table that gets updated at a steady rate. Without
HOT, the updates will disorganize the table and the performance gain you
get from clustered indexes vanishes after a while.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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