Posts by Christo Kutrovsky

Recent Spike Report from v$active_session_history (ASH)

sec p, dsk p, gets p, rows p, cpu p — these are average statistics for the query being executed. This should give you a quick overview of whether the query is a big query, a small query, a CPU-intensive or a disk I/O-intensive query. Be careful: since the query was introduced to the shared pool, those columns are averages, and therefore could be misleading. These are all per execution stats, so sec p represents the number of seconds on average it took to execute the query.

How to Make an In-Database listener.log File

Ever wished the listener.log file was a table in the database? Wish no more! About three years ago, I sent this recipe in an email to my co-workers. Just recently, Shakir re-sent it after using the method in an emergency. Since it seems to have proved its value, I now offer it to our readers. Have a look.

Bind Peeking, Ad Hoc Queries, Stable Performance

I got to troubleshoot an amazing situation a few weeks ago. I think it is essentially inconceivable that allowing a single query to run on your system can flip another query’s plans and cause major performance issues (and in this case even downtime!). Sometimes it’s coincidence, sometimes it’s load, and sometimes it’s a single ad hoc query with a new predicate that starts the slowly-ticking time bomb. Here is how it happens and how to fix it.

Pythian Goodies: The Answer to Free Memory, Swap, Oracle, and Everything

I gave this talk covering the different types of memory, how to monitor memory, and how to optimally use it with Oracle at the UKOUG, I have since received requests to post the slides online. Instead of just posting the PowerPoint I took some time to give the presentation again (internally here at Pythian) and this time we recorded the session and are posting it in a variety of formats. This is a bit of a departure from the typical Pythian Goodies, in that it is scripted, and there is a lot of content here in the whitepaper.

Off to OpenWorld!

Just a quick note to say I’m leaving today for San Francisco to attend Oracle OpenWorld. I’ll be making my presentation on Thursday at 14:30, in Room 304. Look for IOUG: Oracle Database 11g –The Perfection of a Masterpiece (Session ID: S291070).

Metalink Note on Datafile Recovery Will Corrupt Database

Thinking I had something new, I wrote this article about recovering deleted files. However, it turns out Frits Hoogland had already blogged about recovery of deleted files on linux, as Frits pointed out in a comment on my blog, where he also mentioned a metalink note on this matter. The procedure outlined in the note describes how to recover the deleted file and put it in the same location as the deleted file. The problem is that it doesn’t include offlining/onlining the file, so the database ends up with two distinct copies of the file.

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