|
|
JL Computer Consultancy |
|
Index of articles on Miscellaneous Items |
This index covers all the active items on the site. Eventually it will list only those items that do not fall into an obvious category.
Now available through RSS: I don’t know how it works, but if you know how to use RSS, then go to http://feeds.feedburner.com/JonathanLewisArticles to get updates to this page through RSS. For further details on how this was set up see Eddie Awad’s article at http://awads.net/wp/2006/04/17/orana-powered-by-google-and-feedburner/
Now blogging at http://jonathanlewis.wordpress.com
|
Title |
Content |
Last update |
|
Interpreting the x$bh buffer header flag (updated to
9.2.0.1) |
22-Mar-2008
|
|
|
|
|
|
|
If you have several options for handling a problem, it’s the data that dictates the sensible choice. |
1st Dec 2007 |
|
|
A pl/sql package to take snapshots of session-based activity. |
2nd Sept 2007 |
|
|
Statistics – How precise, How Often (updated Aug 2007) |
28th Aug 2007 |
|
|
Capturing the workload of reports run by a report server |
8th Aug 2007 |
|
|
The DUAL table – the sys account – and the not so obvious (updated). |
16th July 2007 |
|
|
Think carefully before you use a script from the internet on a production system (updated) |
14th July 2007 |
|
|
A little lesson in testing (updated) |
14th July 2007 |
|
|
A utility for analyzing logical I/O |
18th Jan 2007 |
|
|
An example of bug hunting a problem with hints by using event 10053 |
18th Jan 2007 |
|
|
Undocumented secrets – or untested fairytales (updated - again) |
7th Jan 2007 |
|
|
There’s no such thing as a function-based index (Recreated from Dizwell Wiki). |
4th Jan 2007 |
|
|
What’s the maximum number of tables you can use in a single query (Recreated from Dizwell Wiki). |
4th Jan 2007 |
|
|
A note on the hints push_pred and no_push_pred, and what it means to push predicates |
7th Dec 2006 |
|
|
A pdf of the Powerpoint slides (2 per page handout format) of a presentation I gave at OpenWorld 2006 |
30th Oct 2006 |
|
|
A pdf of the Powerpoint slides (2 per page handout format) of a presentation I gave at OpenWorld 2006 |
30th Oct 2006 |
|
|
Using analytic functions with statspack data (updated) |
23rd Sept 2006 |
|
|
What’s the cost of a unique constraint ? |
13th Aug 2006 |
|
|
Which advice to follow – humour. |
13th Aug 2006 |
|
|
A taste of the detail that goes into boundary conditions for cost based optimisation. |
13th Aug 2006 |
|
|
A note about hints – and an editor’s stroke of genius |
13th Aug 2006 |
|
|
Sometimes analytics may be too expensive |
14th July 2006 |
|
|
Notes on the cache buffers chains (A short note for the Dizwell Oracle wiki) |
23rd Jun 2006 |
|
|
An article published in the UKOUG magazine – walking through the development of a non-trivial example. |
23rd Jun 2006 |
|
|
Another quick analysis of a statspack question. |
7th Jun 2006 |
|
|
A short article on subquery factoring that I’ve written for the Dizwell Wiki |
6th Jun 2006 |
|
|
An example of making guesses from a tkprof output. |
22nd Apr 2006 |
|
|
Understanding parallelism, plans, and run-time activity |
7th Apr 2006 |
|
|
Just because you’ve fixed a problem that doesn’t mean you understood what the problem was (updated) |
7th Apr 2006 |
|
|
Why test cases are so important, and so helpful (updated) |
5th Apr 2006 |
|
|
A clue to spotting indexes that aren’t used in queries – not that that lets you drop them safely. |
1st Apr 2006 |
|
|
I had an interesting time a couple of weeks ago, being interviewed through a Skype link by Dbazine. |
27th Feb 2006 |
|
|
And just for good measure, here’s Chris Foot’s review for Dbazine of my book |
27th Feb 2006 |
|
|
An insight into how Oracle avoids cache buffers chains latches (an article I’ve started on the Dizwell Oracle wiki) |
31st Jan 2006 |
|
|
Causes and Cures of buffer busy waits (an article I’ve started on the Dizwell Oracle Wiki) |
26th Jan 2006 |
|
|
A simple NT utility to emulate the Unix oerr command (updated after 7 years) |
24th Jan 2006 |
|
|
Finally, they’ve arrived – (a note I wrote for the Dizwell Oracle wiki) |
23rd Jan 2006 |
|
|
The Snark research mechanism (updated) |
7th Jan 2007 |
|
|
Faster sorts – or was it just a hint? |
13th Jan 2006 |
|
|
Create package to take snapshots of rollback segment activity |
5th Jan 2006 |
|
|
High precision cost. (updated 30th Dec) |
30th Dec 2005 |
|
|
Ideas on how to manipulate outlines in 9i and above. |
25th Nov 2005 |
|
|
Some ideas on how cache advice might work (updated) |
23rd Nov 2005 |
|
|
Problems with log file parallel write waits and log file sync waits |
14th Sept 2005 |
|
|
It’s very easy to jump to unsuitable conclusions if you treat the Statspack “Top 5” too casually (updated). |
14th Sept 2005 |
|
|
Using partitioned tables in real life is not always straightforward. Previously published on www.dbazine.com (Updated) |
22nd Aug 2005 |
|
|
Rebuilding indexes – Why, When, How |
30th May 2005 |
|
|
How much work did a session do ? |
29th May 2005 |
|
|
Science and pseudo-science – bluffing with jargon. |
21st May 2005 |
|
|
Is an index much bigger than it ought to be? (Updated) |
20th May 2005 |
|
|
A method for propagating errors and creating myths (updated) |
20th May 2005 |
|
|
Is criticism unprofessional? (Updated) |
26th Apr 2005 |
|
|
Can simple scripts prove anything about performance ? (Corrected and updated) |
15th April 2005 |
|
|
Sometimes you can fix a problem – and find that nothing really changes very much (updated) |
5th April 2005 |
|
|
If you want a sensible debate, shouldn’t you start with a sensible question? |
5th April 2005 |
|
|
The Rumsfeld Box – observations and understanding (pdf file 42K – updated) |
27th Mar 2005 |
|
|
A contribution from our Spanish correspondent (updated) |
20th Mar 2005 |
|
|
Are credentials a substitute for credibility ? (updated) |
15th Mar 2005 |
|
|
Why test cases are important |
13th Mar 2005 |
|
|
In which we don’t trust - a review of silver bullets (updated) |
13th Mar 2005 |
|
|
What is an Oracle scientist? |
4th Mar 2005 |
|
|
Small enhancements in 10g that could make a big difference. Previously published on www.dbazine.com |
26th Feb 2005 |
|
|
A demonstration of how badly b-tree indexes can degenerate. Previously published on www.dbazine.com |
26th Feb 2005 |
|
|
Hit Ratios have their uses (Updated, with added powerpoint/pdf images) |
3rd Jan 2005 |
|
|
An overview of constraints in three parts. . Previously published on www.dbazine.com |
29th Dec 2004 |
|
|
The Evolution of Optimization: 8i to 10g. |
28th Dec 2004 |
|
|
One extent really does do less work! |
6th Nov 2004 |
|
|
Horror, Shock, Gasp !! Howard Rogers says I’m wrong about indexes - what should I do ? |
24th Oct 2004 |
|
|
How tweaking the optimizer_index_cost_adjust parameter can be a bad thing. |
24th Oct 2004 |
|
|
System statistics (the most important 9i optimization enhancement) can cause problems |
16th Oct 2004 |
|
|
A contribution from our |
16th Oct 2004 |
|
|
An introduction to row-level security. Previously published on www.dbazine.com |
23rd Sept 2004 |
|
|
10g fills a performance tuning hole |
23rd Sept 2004 |
|
|
A discussion document on the reasons for rebuilding indexes. Previously published on www.dbazine.com |
19th Sept 2004 |
|
|
One step in identifying indexes that may need rebuilding or coalescing |
30th Aug 2004 |
|
|
An example of a package that takes snapshots of dynamic performance views. |
24th Mar 2004 |
|
|
Can Oracle B-tree indexes get unbalanced, and need rebuilding as a consequence ? Another myth reviewed. Previously published on www.dbazine.com |
26th Sept 2003 |
|
|
Why isn't Oracle using my index - perhaps the commonest question on the Internet. Previously published on www.dbazine.com |
26th Sept 2003 |
|
|
Do you realise how much it costs to update a row ? Especially when your application generator updates every column. Previously published on www.dbazine.com This article can also be found in Russian at http://ln.com.ua/~openxs/articles/jlewis10_ru.html |
26th Sept 2003 |
|
|
An examination of the benefits of Locally Managed Tablespaces. Previously published on www.dbazine.com This article can also be found in Russian at http://ln.com.ua/~openxs/articles/jlewis8_ru.html |
26th Sept 2003 |
|
|
An introduction to the latest Oracle 9 variant on bitmap indexes - the bitmap join index. Previously published on www.dbazine.com |
26th Sept 2003 |
|
|
An explanation of the bitmap star transformation. Previously published on www.dbazine.com |
26th Sept 2003 |
|
|
A discussion of the 'correct' way of creating the stored outline you need. Previously published on www.dbazine.com This article can also be found in Russian at http://ln.com.ua/~openxs/articles/jlewis5_ru.html |
26th Sept 2003 |
|
|
An introduction to the use of Stored Outlines in Oracle 8 – and a look ahead to Oracle 9. Previously published on www.dbazine.com This article can also be found in Russian at http://ln.com.ua/~openxs/articles/jlewis4_ru.html |
26th Sept 2003 |
|
|
A fairly definitive guide to bitmap indexes (excludes bitmap join indexes). Published on www.dbazine.com This article can also be found in Russian at http://ln.com.ua/~openxs/articles/jlewis3_ru.html |
26th Sept 2003 |
|
|
An investigation into a different way of tracing. Previous published on www.dbazine.com. This article can also be found in Russian at http://ln.com.ua/~openxs/articles/jlewis1_ru.html |
26th Sept 2003 |
|
|
An article describing an interesting threat that may arise from third party transaction processing monitors. Published by www.dbazine.com |
26th Sept 2003 |
|
|
A space management oddity when you mix ASSM and bitmap indexes badly. |
14th Feb 2003 |
|
|
A change of marketing direction for Oracle ? |
13-Dec-2002 |
|
|
An Oracle 7 utility to identify who is doing sorting (15K file) |
21-Dec-2001 |
|
|
Yet another simple (Oracle 8) dump of the current parameter list |
23-Nov-2001 |
|
|
How do you convert from Oracle's internal number format to decimal |
2-Nov-2001 |
|
|
Summary management and Query Rewrite with prebuilt tables (addendum) |
26-Oct-2001 |
|
|
The three main variations on block cleanout after commits. |
17-Jan-2001 |
|
|
Folk lore and fairy tales about Oracle databases |
17-Jan-2001 |
|
|
A couple of caveats on using partitioned tables ? |
7-Jan-2001 |
|
|
An introduction to Analytic functions in 8.1.6 |
21-Dec-2000 |
|
|
A correction to v$sort_usage in Oracle 8.1.5 |
24-Nov-2000 |
|
|
How much space is actually free in a data segment (update) |
13-Nov-2000 |
|
|
Seeing the statistics for my own session. |
29-Aug-2000 |
|
|
An insight into optimiser evolution and sorting (7.3 to 8.1) |
29-Aug-2000 |
|
|
An introduction to the basic features of EXPLAIN PLAN |
30-Jun-2000 |
|
|
Explain plan with parallel queries, partitioned table, and some funnies. |
30-Jun-2000 |
|
|
All about sequences (7 and 8) |
24-Sep-1999 |
|
|
Selecting and setting the Oracle SID (Unix) |
7-Sep-1999 |
|
|
How to dump an Oracle 8 block (updated) |
7-Sep-1999 |
|
|
A minor bug in v$sql et. al. that 'loses' SQL text (updated) |
7-Sep-1999 |
|
|
Widening the pipeline from client to server |
17-Aug-1999 |
|
|
Does anyone ever use it ? (Unix) |
17-Aug-1999 |
|
|
What is in the db_block_buffer now (Oracle 8.0) (correction) |
04-Aug-1999 |
|
|
Passing multiple results from SQL*Plus to the shell (Unix) |
04-Aug-1999 |
|
|
Turning a PL/SQL array into an SQL statement (in v7) |
22-Jul-1999 |
|
|
Binding and Bind variables in dbms_sql |
13-Jul-1999 |
|
|
If you really want to, you can do dynamic selects in PL/SQL |
5-July-1999 |
|
|
Generating numeric lists without using a dummy table |
29-Jun-1999 |
|
|
Hash sub-partitions in 8i can give you 2 dimensional partitioning |
23-Jun-1999 |
|
|
One variable interpreted as an IN list (V 8.0) |
12-Jun-1999 |
|
|
Executing dynamic sql in packages as User, not Owner in in v7 |
11-Jun-1999 |
|
|
Turning a PL/SQL table into an SQL statement (v8) |
11-Jun-1999 |
|
|
A better view definition for v$pq_slave (updated) |
11-Jun-1999 |
|
|
A demonstraton of managing concurrent proceses under Oracle |
3-Jun-1999 |
|
|
A package to take performance snapshots - added t/s I/O and filenames |
3-Jun-1999 |
|
|
A mechanism for concurrent execution of lists of tasks |
26-May-1999 |
|
|
A bizarre undocumented feature |
26-May-1999 |
|
|
A way to find out if your session is running with SQL Trace true |
26-May-1999 |
|
|
A cunning (Y2K) plan to update most of a very large table efficiently |
18-May-1999 |
|
|
How to dump an Oracle 7 block. |
18-May-1999 |
|
|
A decimal to Hexadecimal function in PL/SQL |
18-May-1999 |
|
|
Array based dynamic SQL in PL/SQL (8.0) |
6-May-1999 |
|
|
Order of execution in a WHERE clause with NO indexes |
6-May-1999 |
|
|
An idea on allowing ordinary users selective DBA rights |
30-Apr-1999 |
|
|
A little wrapper for simple dynamic SQL |
30-Apr-1999 |
|
|
How Oracle 7 handles small tables and caching |
22-Apr-1999 |
|
|
Oracle 8's answer to Placido Domingo et. al. (and caching) |
22-Apr-1999 |
|
|
A new feature in 7.3.4 for packing a table |
07-Apr-1999 |
|
|
When partition views work better than partition tables |
01-Apr-1999 |
|
|
Spotting memory hungry Oracle processes without connecting |
01-Apr-1999 |
|
|
How in-line views can improve performance dramatically |
25-Mar-1999 |
|
|
Using utl_file to log a series of performance snapshots. |
24-Mar-1999 |
|
|
A study of how the choice can affect Oracle performance |
15-Mar-1999 |
|
|
A very cheap early warning that something is going wrong. |
15-Mar-1999 |
|
|
Building multiple large tablespaces concurrently |
3-Mar-1999 |
|
|
A simple C program to help you pick an Oracle block size |
26-Feb-1999 |
|
|
What's been around but ignored in V$ for Oracle 7 |
26-Feb-1999 |
|
|
A non-invasive PL/SQL tool for performance snapshots |
24-Feb-1999 |
|
|
How effective was your last Parallel Query |
17-Feb-1999 |
|
|
Identifying parallel query slaves that won't die. |
17-Feb-1999 |
|
|
3 scripts for (almost) total performance monitoring (Pts 1,2 &3) |
17-Feb-1999 |
|
|
db_block_buffers can be too big |
10-Feb-1999 |
|
|
Sometimes fewer extents to an object is a good thing |
10-Feb-1999 |
|
|
A class of queries that makes Explain Plan go wrong |
10-Feb-1999 |
|
|
A sample of awk, cut,and paste for low-impact monitoring (UNIX) |
10-Feb-1999 |
|
|
What's new in the V$ area for Oracle 8 (and a symmetric difference) |
3-Feb-1999 |
|
|
Some real life experience with the Parallel Query Option (7.3) |
3-Feb-1999 |
|
|
An introduction to the Parallel Query Option (7.3) |
27-Jan-1999 |
|
|
A small C program to tidy up the listing from v$sql_text |
27-Jan-1999 |
|
|
A data warehouse case study |
21-Jan-1999 |
|
|
An undocumented (X$) object to see where v$waitstat is happening |
21-Jan-1999 |
|
|
An idea for switching sql_trace on selectively in production systems |
21-Jan-1999 |
|
|
An introduction to Partition Views (7.3) |
14-Jan-1999 |
|
|
Who's the sinner and what's (s)he doing right now (Unix only) |
14-Jan-1999 |
|
|
V$ Views - a health warning |
14-Jan-1999 |
|
|
A Partition Elimination anomaly in partition tables (and views) |
09-Jan-1999 |
|
|
A comparison of 7.3 partition views and 8.0 partition tables |
09-Jan-1999 |
|
|
Bitmap indexes in Oracle 7.3.2 |
09-Jan-1999 |
|
|
What does SMON do. |
08-Jan-1999 |
|
|
The oldest bug in Oracle ? |
07-Jan-1999 |
|
|
A convenient framework for running explain plan against Oracle 8 |
07-Jan-1999 |
|
|
A convenient framework for running explain plan against Oracle 7.3 |
07-Jan-1999 |