Optimizer debug trace event, trace file. You are commenting using your Facebook account. I always wondered how and why Oracle optimizer decides to choose one execution plan to other. What is needed to diagnose a SQL Tuning issue? I could have also forced a hard parse by placing the random string in a comment:. Interpreting Event trace file example — http:
By continuing to use this website, you agree to their use. Leave a Reply Cancel reply Enter your comment here Here is how demo. I could have also forced a hard parse by placing the random string in a comment: Leave a Reply Cancel reply Enter your comment here
The trace file we produce has lots of information as expected; all session optimizer parameter values and every table, index and possible access path statistics etc. You are commenting using your Twitter account.
The reason for examining a snalyzing typically to understand why the CBO made its decisions.
Oracle Database – Trace File 10053 to understand the Optimizer (CBO)
The good plan is basically a shorter version of the bad plan one in which no indexes were considered. Every so often I see on a distribution list a posting that starts like this: The first trace file has a continuation message on to the second: By continuing to use this website, you agree to their use.
Our task here is to analyze the bad plan and determine analzing the CBO computed the costs that led to the cheaper, but acse plan. Fill in your details below analyaing click an icon to log in: It is available at Amazon and many other retailers. Optimizer debug trace event, trace file The trace file we produce has lots of information as expected; all session optimizer parameter values and every table, index and possible access path statistics etc.
Scripts for trace 10053
I tried to create a small demostration for a better understanding of this event dump, following script creates a table with a primary key and unique key constraints and the CBO decides to use the unique key constraint over primary key; Code listing No such file or directory -rw-r 1 oracle asmadmin Aug 7 The collected files can be reviewed, analyzed, and compared.
Here is a one-line script for starting the trace You are commenting using your Google account. Filse dynamic sampling appears. Disclaimer All my postings reflect my own views.
Whoops, where is my second trace file?
I expect this pilot session to fill out fast. The row length would have to come from the catalog. Notice also the trace file continuation message from file A to file B: Stelios Charalambides has done an excellent job writing a book on this topic. To find out more, including how to control cookies, see here: Our Support Case Studies are created for the purpose of sharing information and for transferring knowledge related to a complex event, process, procedure, or to a series of events.
The main fact to remember when you are collecting trace is that you must force a hard parse each time you run your statement. This workshop is packed with lots of content. Use and events for detail analysis of CBO decisions, changing the value of an znalyzing parameter for a […].
Oracle Database – Trace File to understand the Optimizer (CBO) [Gerardnico]
Oracle Support Case Studies are written by support engineers who work with customers on a daily basis. Cost-based query optimization is something we must call the real computer science, a hard thing to do and with every new file Oracle optimizes the code dramatically. You are commenting using your WordPress. It simply saves a lot of time!