On 10/11/2012 01:06 AM, Franck Routier wrote:
Hi,
I have pretty large tables, with columns that might never receive any
data, or always receive data, based on the customer needs.
The index on these columns are really big, even if the column is never
used, so I tend to add a "where col is not null" clause on those indexes.
What are the drawbacks of defining my index with a "where col is not
null" clause ?
* You can't CLUSTER on a partial index; and
* The partial index will only be used for queries that use the condition
"WHERE col IS NOT NULL" themselves. The planner isn't super-smart about
how it matches index WHERE conditions to query WHERE conditions, so
you'll want to use exactly the same condition text where possible.
--
Craig Ringer
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