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Oracle Tips by Burleson |
Tracing a user’s session
The trace file that was produced is over 40
million lines long. To gain a better understanding of what this
session, some basic analysis can be performed using simple UNIX
operating system commands.
The first step is to determine how many of
those events were WAIT events rather than PARSE, EXEC or FETCH
events were. There were 19,677 WAIT events, over 13 million EXEC
events, 0 PARSE events and over 13 million FETCH events. In fact,
the number of FETCH events matches the number of EXEC events. The 0
parses probably reflect the fact that all the SQL statements being
used by this process had already been parsed before tracing began.
However, it is a good indicator that the problems are not due to
excessive parsing. Now it is time to determine what the primary
WAIT events were.
Opening the trace file in a text editor
is probably not a good idea since the file is roughly 2 GBs and it
will either crash the editor or tie up the session for a long time.
A better way would be to cat the file with grep and head to look at
the first handful of events in order to get a feel for the types of
WAIT events.
The above book excerpt is from:
Oracle Wait Event Tuning
High Performance with Wait
Event Iinterface Analysis
ISBN 0-9745993-7-9
Stephen Andert
http://www.rampant-books.com/book_2004_2_wait_tuning.htm |
