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.
Therefore I produced a patch which adds a 'discarded=%f' part to the
As this is only a RFD the implementation is a bit hackish at the moment
- the discarded counter is increased in execScan directly instead of a
helper routine in instrument.c.
Also the discarded count is displayed in other node types as well - for
some there might be a sensible semantic meaning to it...
Good idea - Bad idea?
pgsql-hackers by date
|Next:||From: Andres Freund||Date: 2009-05-22 13:40:41|
|Subject: Re: RFD: Discarded tuple count for SeqScan nodes in EXPLAIN
ANALYZE - Patch v1|
|Previous:||From: Gevik Babakhani||Date: 2009-05-22 12:39:00|
|Subject: Re: A humble request|