Blog: Jonathan Lewis

208 blogs updated: 18 min. ago
With Subquery()
Here's a little oddity that came up recently on the OTN database forum an example where a "with" subquery (common table expression / factore...
19-09-2017 21:31:20 Jonathan Lewis Oracle
Join Elimination Bug
A few years ago a bug relating to join elimination showed up in a comment to a post I'd done about the need to keep on testing and learining...
14-08-2017 13:52:56 Jonathan Lewis Oracle
Rebuilding Indexes
One of the special events that can make it necessary to rebuild an index is the case of the "massive DML", typically a bulk delete that purg...
03-08-2017 14:54:07 Jonathan Lewis Oracle
Redo OP Codes:
This posting was prompted by a tweet from Kamil Stawiarski in response to a question about how he'd discovered the meaning of Redo Op Codes ...
25-07-2017 19:47:21 Jonathan Lewis Oracle
Fast Now, Fast Later
The following is the text of an article I published in the UKOUG magazine several years ago (2010), but I came across it recently while writ...
24-07-2017 14:49:49 Jonathan Lewis Oracle
In Memoriam – 2
This is the second of two items that my mother typed out more than 25 years ago. I had very mixed emotions when reading it but ultimately I ...
22-07-2017 18:16:41 Jonathan Lewis Oracle
The title is a well-known shorthand for parameter optimizer_features_enable and it has been the topic of a recent blog post by Mike Dietrich...
07-07-2017 15:22:40 Jonathan Lewis Oracle
In Memoriam
My mother died a few weeks ago after a couple of months in terminal care. One of my tasks while she was in care was to go through all her pa...
05-07-2017 18:29:55 Jonathan Lewis Oracle
An interesting observation appeared recently as a side-channel on a question on the OTN database forum how does Oracle execute an unpivot() ...
14-06-2017 17:53:34 Jonathan Lewis Oracle
If you're familiar with SQL Profiles and SQL Baselines you may also know about SQL Patches a feature that allows you to construct hints that...
12-06-2017 13:56:20 Jonathan Lewis Oracle

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