Blog: Jonathan Lewis

210 blogs updated: 71 min. ago
Column Stats
A little while ago I added a post-script to a note I'd written five years ago about gathering stats on a virtual column and had updated with...
12-09-2018 15:40:14 Jonathan Lewis Oracle
Stats time
I wrote a note a couple of years ago explaining how I used to get a rough idea (with some errors) of how much time was spent in the overnigh...
10-09-2018 15:01:40 Jonathan Lewis Oracle
Subquery Order
From time to time I've wanted to optimize a query by forcing Oracle to execute existence (or non-existence) subqueries in the correct order ...
05-09-2018 15:10:28 Jonathan Lewis Oracle
My entrance at the Polish Oracle User Group conference 2017 has just resurfaced on Twitter. There is a back-story to this which contains an ...
29-08-2018 12:20:26 Jonathan Lewis Oracle
Error Logging
Error logging is a topic that I've mentioned a couple of times in the past, most recently as a follow-up in a discussion of the choices for ...
24-08-2018 13:26:32 Jonathan Lewis Oracle
Descending bug
Following on from Monday's posting about reading execution plans and related information, I noticed a question on the ODC database forum ask...
22-08-2018 15:20:28 Jonathan Lewis Oracle
Masterclass – 1
A recent thread on the Oracle developer community database forum raised a fairly typical question with a little twist. The basic question is...
20-08-2018 12:13:06 Jonathan Lewis Oracle
Extended Histograms – 2
Following on from the previous posting which raised the idea of faking a frequency histogram for a column group (extended stats), this is ju...
02-08-2018 15:40:34 Jonathan Lewis Oracle
Extended Histograms
Today's little puzzle comes courtesy of the Oracle-L mailing list. A table has two columns (c2 and c3), which contain only the values Y' and...
01-08-2018 00:52:14 Jonathan Lewis Oracle
Direct IOT
A recent (automatic ?) tweet from Connor McDonald highlighted an article he'd written a couple of years ago about an enhancement introduced ...
16-07-2018 14:27:06 Jonathan Lewis Oracle

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