On 9/10/07, Heikki Linnakangas <heikki@enterprisedb.com > wrote:
Oh, one more thing occured to me. Without HOT, we not only mark index
tuples pointing to dead tuples as killed, we remove them altogether if
the index page gets full. If you modify the test case so that after
doing the updates, you insert a bunch of tuples with a different key to
fill the index page, you should see CVS HEAD winning HOT without pruning
hands down.
Um. I am not sure I follow that. With HOT even if the HOT chain is long,
there is still just one index entry for the entire chain. So I don't see
why CVS HEAD would do better than HOT in the above case. Net-net
there will be equal number of index keys after the inserts.
Thanks,
Pavan
--
Pavan Deolasee
EnterpriseDB
http://www.enterprisedb.com