[Toolserver-l] Fwd: [TS] Killed SQL-Task 15233729 on db-server z-dat-s6-a
Once again, a question on query killer. Below its report informs that with near-zero replag a very simple count(*) only query on s6 takes too long, and the killer expects SLOW_OK would help. I think something is wrong fundamentally once such a query takes that long, and there is no reason to add SLOW_OK and wait even longer. mashiah -- Forwarded message -- From: no-re...@toolserver.org Date: Sat, Nov 5, 2011 at 1:28 AM Subject: [TS] Killed SQL-Task 15233729 on db-server z-dat-s6-a To: mash...@toolserver.org Hello mashiah, a MySQL-query of yours was killed because you didn't mark it as SLOW_OK and it have run for 853 seconds which was longer than allowed. You can find the query below. Please have also a look at [1] to find information how you can avoid killings of your queries. Maybe you can optimze the query too? The replication lag at kill-time was 33s. Sincerly, Query-Killer. This eMail was sent automaticaly, please don't reply. SELECT count(*) INTO @tl_count FROM ruwiki_p.templatelinks [1] https://wiki.toolserver.org/view/Database_access#Slow_queries_and_the_query_killer ___ Toolserver-l mailing list (Toolserver-l@lists.wikimedia.org) https://lists.wikimedia.org/mailman/listinfo/toolserver-l Posting guidelines for this list: https://wiki.toolserver.org/view/Mailing_list_etiquette
Re: [Toolserver-l] Fwd: [TS] Killed SQL-Task 15233729 on db-server z-dat-s6-a
Mashiah Davidson mashiah.david...@gmail.com wrote: Once again, a question on query killer. Below its report informs that with near-zero replag a very simple count(*) only query on s6 takes too long, and the killer expects SLOW_OK would help. I think something is wrong fundamentally once such a query takes that long, and there is no reason to add SLOW_OK and wait even longer. [...] SELECT count(*) INTO @tl_count FROM ruwiki_p.templatelinks [...] I don't know about MySQL, but usually COUNT is rather slow as it has to look up for every row if it is visible to the current transaction. When did you start using it? :-) Tim ___ Toolserver-l mailing list (Toolserver-l@lists.wikimedia.org) https://lists.wikimedia.org/mailman/listinfo/toolserver-l Posting guidelines for this list: https://wiki.toolserver.org/view/Mailing_list_etiquette
Re: [Toolserver-l] Fwd: [TS] Killed SQL-Task 15233729 on db-server z-dat-s6-a
When did you start using it? :-) I do that for long and most of my time consuming queries are marked by SLOW_OK. This one started being killed just recently, that's why I noticed this just today. It could be that this query did not work too fast in the past but at the same time it did not happen to it to be killed, so I conclude it became slower recently. Does my SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED; improve usual MySQL speed on count(*)? mashiah ___ Toolserver-l mailing list (Toolserver-l@lists.wikimedia.org) https://lists.wikimedia.org/mailman/listinfo/toolserver-l Posting guidelines for this list: https://wiki.toolserver.org/view/Mailing_list_etiquette
