Oracle Scratchpad

December 31, 2013


Filed under: Oracle,Troubleshooting — Jonathan Lewis @ 5:30 pm BST Dec 31,2013

If it’s a long night, and you’ve got nothing better to do waiting for the new year, then here’s some reading to keep you entertained. A collation of Tanel Poder’s trouble-shooting blog postings, dating from June 2007 to April 2015:

  1. When the wait interface is not enough
  2. No magic is needed, systematic approach will do
  3. More adventures in the process stack
  4. Diagnosing a long parsing issue
  5. Sampling v$ stuff with waitprof really fast using SQL
  6. Understanding execution plans with OS explain
  7. Sampling latch holder statistics using latchprof
  8. Even more details latch troubleshooting using latchprofx
  9. Process stack profiling from SQL Plus using ostackprof
  10. Index unique scan doing multiblock reads
  11. Complex wait chain signature analysis with ash_wait_chains sql
  12. Control file reads causing Enq: SQ waits

And a bonus article with Tanel’s latch touble-shooting scripts.


  1. Beware colorizing your SQL prompt and other SQL bits.
    That is a big time sink – when you look up at the clock you will be wondering where all the time went.

    Comment by Jared — December 31, 2013 @ 8:00 pm BST Dec 31,2013 | Reply

    • Jared,

      Your observation captures a serious problem in the industry – too much concern about the pretty wrapping, not enough interest in the quality of the package.

      Comment by Jonathan Lewis — January 1, 2014 @ 11:47 am BST Jan 1,2014 | Reply

    • Jared,

      I’d picked up the wrong “part 6” in my original list – and the correction to that error has lost the context of your comment.

      Comment by Jonathan Lewis — January 2, 2014 @ 10:15 pm BST Jan 2,2014 | Reply

  2. Wow thanks! :-) I have been thinking about some sort of an index of my troubleshooting posts for a while… for the last 5 years, to be honest :) Thanks for actually doing it :)

    Comment by Tanel Poder (@TanelPoder) — January 1, 2014 @ 6:28 am BST Jan 1,2014 | Reply

    • Tanel,

      I’ve had the list in a file “somewhere” on my laptop for the last couple of years – then I realised there was an obvious way to put it so that I could easily remember where it was.

      Comment by Jonathan Lewis — January 1, 2014 @ 11:48 am BST Jan 1,2014 | Reply

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