When checking an index in postgres the original table has to be checked for each result to find if the index entry is still valid? In which case you can't blindly scan the whole index and assume the data is good. I was used to Oracle behavior where the index is up to date so it can do the scan without hitting the original table.

Does this sound correct to anyone?


Stephan Szabo writes:
On Fri, 23 Apr 2004 [EMAIL PROTECTED] wrote:

I have a query which I think should be using an index all of the time but
postgres only uses the index part of the time.  The index
(ticket_crm_map_crm_id_suppid) has the where clause column (crm_id) listed
first followed by the selected column (support_person_id).  Wouldn't the
most efficient plan be to scan the index each time because the only columns
needed are in the index?  Below is the table, 2 queries showing the

Not necessarily. The rows in the actual file still need to be checked to
see if they're visible to the select and if it's expected that the entire
file (or a reasonable % of the pages anyway) will need to be loaded using
the index isn't necessarily a win.

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