Oracle Scratchpad

May 15, 2010

Contention

Filed under: humour,Oracle,Performance,Troubleshooting — Jonathan Lewis @ 10:44 am BST May 15,2010

There was a news item in the UK last week about a man in Chideock, Dorset who staged a protest about the volume of heavy traffic that has to come through the village where he lives.

A pedestrian crossing has recently been installed on the road, using traffic-light control. So one morning he decided to cross the road, and then come back again, non-stop, for an hour. Each time he got across the road he pressed the crossing control button to come back. A few vehicles got through on the green light each time, but after just one hour he had caused a four mile tailback of traffic.

Let this be a lesson to Oracle DBAs and developers – even a small job, if repeated very frequently, can create havoc with your system.

4 Comments »

  1. if you are a oracle DBA , you should have know this type of simulations in Oracle. Some times we can’t find long running one single sql, but DB CPU is high.
    But even when optimized sql runs repeatedly , you face the same difficulty.

    So even a small job, if repeated very frequently, there should be a LIMIT for it.

    Comment by david — May 15, 2010 @ 5:59 pm BST May 15,2010 | Reply

  2. Once, there wad this application and it had a module with a pool of open connections the app would use to query the database, something like jboss, but made in-house.

    This module made queries to keep the connections opened. The developer thought it would be a nice idea to select xxx.xx from dual several times per second, where xxx.xx is a any number between 000.00 and 999.99. I still don’t know if this number was random or incremental, but you can try and guess how it screwed the database :P

    Comment by Daniel Stolf — May 15, 2010 @ 6:30 pm BST May 15,2010 | Reply

  3. “alter system kill pedestrian” would have handled the job nicely :-)

    Comment by Connor — May 17, 2010 @ 4:51 am BST May 17,2010 | Reply

  4. Here’s the followup to the original story: http://www.guardian.co.uk/uk/2010/may/24/pedestrian-crossing-protest-traffic-superglue

    Comment by rnm1978 — May 24, 2010 @ 10:29 am BST May 24,2010 | Reply


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