Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder1.news.weretis.net!news.solani.org!.POSTED!not-for-mail From: Mladen Gogala Newsgroups: comp.databases.postgresql Subject: Re: Performance views/tables in PostgreSQL? Date: Fri, 23 Mar 2012 05:04:28 +0000 (UTC) Organization: solani.org Lines: 27 Message-ID: References: <4f69f15e@news.x-privat.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Trace: solani.org 1332479068 5557 eJwFwYEBgDAIA7CXQGhh5zCl/59ggqDzrSSYENTO9Ol7uCNjTz9uXNAGz4RyL0+p6tsI0/4M8BDa (23 Mar 2012 05:04:28 GMT) X-Complaints-To: abuse@news.solani.org NNTP-Posting-Date: Fri, 23 Mar 2012 05:04:28 +0000 (UTC) User-Agent: Pan/0.133 (House of Butterflies) X-User-ID: eJwFwYEBwDAEBMCVaJA3Di/2H6F3fkKD18LDfH3JyRS8fqzQ7bT1UpgeU/kuRljNKgyMjvkBMHoRvQ== Cancel-Lock: sha1:W4uB5l/s66JK9DCTRqoVIo3yNGg= X-NNTP-Posting-Host: eJwFwQEBACAIA7BKHDiaB/D9I7gxCjUni5UUtSYwGaP0AG7G9XJ6y97oCdY7oWOyjF58DDYQ5g== Xref: csiph.com comp.databases.postgresql:327 On Thu, 22 Mar 2012 12:57:52 +0000, Jasen Betts wrote: > explain analyze is the most commonly used query performance metric. > > I think there may be something else too. With all due respect, there is nothing like the Oracle wait interface in the free version of PostgreSQL. Nada. Zilch. Explain plan answers the question "how will Postgres execute my query". The wait interface answers the question "where is the time spent". Note that explain plan answers the question about the future and wait interface answers the question about the past. Explain plan cannot tell you whether your application was waiting for lock, resolving a deadlock or simply dealing with a slow disk. It may not even be a database problem at all. Java application may have a bug ,causing it to sleep and not wake up until kissed by a prince, which doesn't happen that frequently. Oracle will tell you that it's waiting for the more data from SQL*Net, so you can start looking into the application. Postgres will also allow you to make that conclusion, but not directly. You will see no activity on the server and conclude that there is a problem with the application itself. -- http://mgogala.byethost5.com