I'm sorry for the bad example. Here is another, with some data on PG: [ https://dbfiddle.uk/?rdbms=postgres_13&fiddle=ccfd1c4fa291e74a6db9db1772e2b5ac | https://dbfiddle.uk/?rdbms=postgres_13&fiddle=ccfd1c4fa291e74a6db9db1772e2b5ac ] and Oracle: [ https://dbfiddle.uk/?rdbms=oracle_18&fiddle=21a98f499065ad4e2c35ff4bd1487e14 | https://dbfiddle.uk/?rdbms=oracle_18&fiddle=21a98f499065ad4e2c35ff4bd1487e14 ] .
I don't understand oracle's execution plan very well, but it doesn't seem to be hitting the Users table... De: "Fabrízio de Royes Mello" <fabri...@timbira.com.br> Para: "luis.roberto" <luis.robe...@siscobra.com.br> Cc: "pgsql-general" <pgsql-general@lists.postgresql.org> Enviadas: Sábado, 11 de julho de 2020 15:24:04 Assunto: Re: Join optimization Em sáb, 11 de jul de 2020 às 14:20, < [ mailto:luis.robe...@siscobra.com.br | luis.robe...@siscobra.com.br ] > escreveu: Hi! Recently on a blogpost [1] I saw that Oracle was able to "optimize" a join strategy by completely eliminating access to a table. Heres the execution on Oracle 18c [2] and PostgreSQL 13 (beta) [3]. Is there a fundamental reason why PG can't do the same? It does... did you see the “never executed” notice on the Postgres explain output? Regards, BQ_BEGIN BQ_END -- Fabrízio de Royes Mello Timbira - [ http://www.timbira.com.br/ | http://www.timbira.com.br/ ] PostgreSQL: Consultoria, Desenvolvimento, Suporte 24x7 e Treinamento
