Abhijit Menon-Sen wrote:
At 2008-08-25 10:24:01 +0300, [EMAIL PROTECTED] wrote:
My original plan was to enable index-only-scans using the DSM as well
for 8.4, but it's pretty clear at this point that I don't have the
time to finish that :-(.
I wonder how hard that would be.
It's doable, for sure.
The pieces I see as required for that are:
1. change the indexam API so that indexes can return tuples
2. make sure the DSM is suitable for index-only-scans. Ie. it must be
completely up-to-date and WAL-logged, so that if the DSM says that all
tuples on a page are visible, they really must be.
3. planner/stats changes, so that the planner can estimate how much of
an index scan can be satisfied without looking at the heap (it's not an
all-or-nothing plan-time decision with this design)
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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