Hi,
On 05/22/2009 03:42 PM, Heikki Linnakangas wrote:
Andres Freund wrote:
When analyzing the plan of a query I often find myself questioning
whether an additional index may be sensible, or if it is sensible that
a SeqScan is used if an index is available.
The current EXPLAIN ANALYZE only shows the number of tuples matching
the qualifier of an SeqScan Node - for analyzing the above situation
it is at least equally interesting how many tuples were read and
discarded.
Good idea - Bad idea?
Isn't the discarded count always equal to (# of rows in table - matched
tuples)? Seems pretty redundant to me.
Not for EXISTS(), LIMIT and similar.
Also when looking at more complex plans its quite a nuisance to go
through all participating tables and do a separate count(*). Especially
its not your plan but some clients plan etc.
Andres
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