Re: Tecnical Help (Celso)

>From: uunet!microc!eric >Message-Id: <9202111625.AA03183@relay2.UU.NET> >To: widener!emory!rmy!informix-list >Subject: Tecnical Help (Celso) >Date: Tue Feb 11 09:25:16 1992 > >Hi Informaniacs! > >This is an e-mail I sent to Informix to see if they could help, but >still no response. Can somebody help me here? Who did you send it to? > 1. The indexes get corrupted too often. They think it is > because when an sqlexec process gets frozen, they issue a > kill -9 command. I told them to use kill -1 instead. Is > this correct to do? If not, how can I kill an sqlexec? > Also they say that the integrity of the database is in > jeopardy, because they read the release notes and it says > you have to recover a backup and issue a rollforward and > they believe that begin work ... commit work do not work > automatically. Is that right? a. Why is the sqlexec freezing? Are there enough locks? b. As far as possible, never kill an sqlexec. That means, don't send it any signals. Don't use kill. OK: sometimes it will be necessary to send signals; you could try sending SIGPIPE (kill -13) which tells the engine that it's front-end has died. But you must allow the engine time to roll back. This can take several minutes! But if you kill it viciously (-9) before it's finished rolling back, the database will be corrupted! Permanently. So be very careful before killing any database engine, especially sqlexec. You can kill front-ends with impunity. But not the back-end. > 2. The optimizer is not working (?). They say that a large > query they developed takes almost 80% of the CPU and almost > ALL memory! What is the query? What does SET EXPLAIN ON have to say? When did you last run UPDATE STATISTICS? How much data is there in the tables? Are the indexes in the correct place? Yours sincerely, Jonathan Leffler (johnl@obelix.informix.com)