Blog: Jonathan Lewis

211 blogs updated: 63 min. ago
The title is the name of an Oracle hint that came into existence in Oracle and made an appearance recently in a question on the rar...
15-11-2018 14:49:16 Jonathan Lewis Oracle
Index Splits – 3
This is stored only for reference, and in case anyone wants to wade through the details. It's the redo log dump from the 90/10 index leaf bl...
13-11-2018 21:48:56 Jonathan Lewis Oracle
Where / Having
There's a very old mantra about the use of the "having" clause that tells us that if it's valid (i.e. will always give the same results) the...
08-11-2018 13:50:30 Jonathan Lewis Oracle
UKOUG Tech 18
One month to go before the big event in Liverpool. so I've been browsing the agenda to get some idea of the talks I'll probably go to. At pr...
05-11-2018 12:15:37 Jonathan Lewis Oracle
Join Cardinality – 5
So far in this series I've written about the way that the optimizer estimates cardinality for an equijoin where one end of the join has a fr...
01-11-2018 15:38:50 Jonathan Lewis Oracle
Index Splits – 2
In yesterday's article I described the mechanism that Oracle for an index leaf block split when you try to insert a new entry into a leaf bl...
30-10-2018 15:13:11 Jonathan Lewis Oracle
Index splits
After writing this note I came to the conclusion that it will be of no practical benefit to anyone but I'm publishing it anyway because it's...
29-10-2018 15:00:11 Jonathan Lewis Oracle
Upgrades – again
I've got a data set which I've recreated in and I've generated stats on the data set, and the stats are identical. I don'...
28-10-2018 14:35:26 Jonathan Lewis Oracle
Join Cardinality – 4
In previous installments of this series I've been describing how Oracle estimates the join cardinality for single column joins with equality...
25-10-2018 11:09:14 Jonathan Lewis Oracle
Upgrade threat
Here's one I've just discovered while trying to build a reproducible test case that didn't reproduce because an internal algorithm has chang...
23-10-2018 21:09:49 Jonathan Lewis Oracle

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