On 4/29/14, Achilleas Mantzios <achill@xxxxxxxxxxxxxxxxxxxxx> wrote: > On 29/04/2014 09:59, David Noel wrote: >> "select page.*, coalesce((select COUNT(*) from sentence where >> sentence."PageURL" = page."URL" group by page."URL"), 0) as >> NoOfSentences from page WHERE "Classification" LIKE CASE WHEN "<>" >> THEN " ELSE '%' END ORDER BY "PublishDate" DESC Offset 0 LIMIT 100" > > In all honesty, this query is very badly written. It seems like it was > ported from some other > system. The inner group by in the coalesce is redundant since the result is > always one row, > moreover, it is wrong since coalesce accepts a scalar value, it hits the eye > at first sight. > Additionally, ''<>'' always returns false, what's the purpose of the CASE > statement? Ok, thanks for the heads up. It confused me, too. It's code I'm just picking up from another developer, so I don't know why it was done the way it was done. I'm not super proficient with SQL but I'll take a stab at rewriting it. > Try to re-write the query in a good form, and then perform EXPLAIN ANALYZE > on both systems to see what's wrong. Will do. Thanks for the advice. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
