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December 2009

Measurement Error Trap In Trace File (event 10046)

Some time ago I had an interesting case which I can use to clearly describe how one can be caught in measurement error trap.

But let us start at the beginning with this response time analysis:

Response Time Component Time % Elap AvgEla
---------------------------------------- ----------- ------- ---------
CPU service 3934.97s 48.39% 0.000716
un-accounted for time 1363.01s 16.76%
db file sequential read 1122.00s 13.80% 0.032253
gc buffer busy 451.73s 5.56% 0.011746
log buffer space 451.64s 5.55% 0.123974
buffer busy waits 176.79s 2.17% 0.029579

UKOUG 2009 - The Slides

As promised in one of my comments here are the slides of the presentations I did at UKOUG 2009.

I've already considered some of the valuable feedback I got - in particular for the FIRST_ROWS_N presentation since it was the first time I did this one.

So those downloads are even valuable for those who attended my sessions - they offer a couple of goodies:

1. The "CBO fundamentals: Understanding System Statistics" slides have a part "The gory details" right after the official end of the presentation where you can find the really "gory" details, if anyone is interested

2. The "Everything You Wanted To Ask About FIRST_ROWS_N But Were Afraid To Ask" presentation has been revised - in particular I have worked on those parts of the slides that were "suboptimal" so far. The complex pagination queries are now better readable and explained step-by-step which I think makes them much simpler to understand, but also some other parts have been re-worked and extended.

Furthermore the slides for this presentation are available in two versions: The presentation slides, and additionally the notes where I explain some more details for those who are interested.

Here are the links to the downloads:

"CBO fundamentals: Understanding System Statistics"

"Everything You Wanted To Ask About FIRST_ROWS_N But Were Afraid To Ask"

"Everything You Wanted To Ask About FIRST_ROWS_N But Were Afraid To Ask" - Notes

Anydata and anytype in 9i

An introduction to generic types in Oracle 9i. October 2002 (updated July 2007)

The collect function in 10g

Using the new 10g COLLECT group function, including string aggregation. June 2004 (updated July 2008)

Binding in-lists in 10g

Alternative IN-list binding in 10g using the new MEMBER OF collection condition. June 2004 (updated September 2008)

Collection extensions in 10g

A brief overview of the new collection operators, functions and conditions in 10g. June 2004

Emulating string-to-table functionality using sql

Turning delimited strings into multiple records without PL/SQL. July 2005 (updated August 2007)

Row-generation without i/o

Methods for generating dummy data without incurring I/O costs. November 2004

Encapsulating bulk pl/sql exceptions

Using object features to encapsulate FORALL .. SAVE EXCEPTIONS error-handling. July 2007

Setting cardinality for pipelined and table functions

Various methods for setting accurate cardinality statistics for table/pipelined functions. June 2009