johno wrote > Thanks for the quick reply David! > > However I am still unsure how these two queries are not relationally > equivalent. I am struggling to find a counterexample where the first and > third query (in email, not in gist) would yield different results. Any > ideas? Remove the outer LIMIT 100 from both queries... The first query would return a maximal number of rows that meet the OR criteria while the second query would return at most 200 rows since both sub-queries would still have their own independent LIMIT 100 clauses. David J. -- View this message in context: http://postgresql.1045698.n5.nabble.com/Slow-query-with-indexed-ORDER-BY-and-LIMIT-when-using-OR-d-conditions-tp5812282p5812289.html Sent from the PostgreSQL - performance mailing list archive at Nabble.com.
