Re: limit + order by is slow if no rows in result set

Brian Cox wrote:
>
> There are 1.9M rows in ts_defects and indexes on b.ts_id (primary key)
> d.ts_biz_event_id and d.ts_occur_date.  Both queries below return 0
> rows.  The 1st runs fast and the 2nd > 400x slower.  The 2nd query
> differs from the 1st only by the addition of "limit 1".
>
> Why the big difference in performance?

Please run EXPLAIN ANALYZE on both queries, and send back the results.
Also, what indexes are there on the tables involved?

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   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com