> I really thought that Postgresql would rewrite a query from > > select * > from file a, file_tag b, tag c > where a.id_file=b.id_file and b.id_tag=c.id_tag and a.id_file=10000001000000 > > to something like: > > select * > from (file a inner join file_tag b on (a.id_file=b.id_file)) inner join > tag c on (b.id_tag=c.id_tag) > where a.id_file=10000001000000
These shouldn't be other than two ways to express the same (inner) join. Your timings seem to suggest that in the first case PG computes the whole join between 3 tables and only then applies the filter in a. Can you send the outputs of "explain <query>" for these two and let us know what version of PG this is? Bye, Chris. -- Chris Mair http://www.1006.org ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
