Clik here to view.
Invalidation
Someone who attended my sessions at the Bucharest Oracle Summit earlier on this year sent me an example of a quirky little bug, possibly related to the newer “fine-grained” invalidation mechanisms,...
View ArticleClik here to view.
Subquery Factoring (10)
What prompted me to write my previous note about subquerying was an upgrade to 12c, and a check that a few critical queries would not do something nasty on the upgrade. As ever it’s always interesting...
View ArticleClik here to view.
IN/EXISTS bugs
Here’s a simple data set – I’m only interested in three of the columns in the work that follows, but it’s a data set that I use for a number of different models: execute dbms_random.seed(0) create...
View ArticleClik here to view.
Result Cache
Yesterday I thought I’d spend half an hour before breakfast creating a little demonstration of a feature; some time about midnight I felt it was time to stop because I’d spent enough time chasing...
View ArticleClik here to view.
12c Downgrade
No, not really – but sometimes the optimizer gets better and gives you worse performance as a side effect when you upgrade. Here’s an example where 11.2.0.4 recognised (with a few hints) the case for a...
View ArticleClik here to view.
Invalidation
Someone who attended my sessions at the Bucharest Oracle Summit earlier on this year sent me an example of a quirky little bug, possibly related to the newer “fine-grained” invalidation mechanisms,...
View ArticleClik here to view.
Subquery Factoring (10)
What prompted me to write my previous note about subquerying was an upgrade to 12c, and a check that a few critical queries would not do something nasty on the upgrade. As ever it’s always interesting...
View ArticleClik here to view.
IN/EXISTS bugs
Here’s a simple data set – I’m only interested in three of the columns in the work that follows, but it’s a data set that I use for a number of different models: execute dbms_random.seed(0) create...
View ArticleClik here to view.
Result Cache
Yesterday I thought I’d spend half an hour before breakfast creating a little demonstration of a feature; some time about midnight I felt it was time to stop because I’d spent enough time chasing...
View ArticleClik here to view.
12c Downgrade
No, not really – but sometimes the optimizer gets better and gives you worse performance as a side effect when you upgrade. Here’s an example where 11.2.0.4 recognised (with a few hints) the case for a...
View ArticleClik here to view.
Invalidation
Someone who attended my sessions at the Bucharest Oracle Summit earlier on this year sent me an example of a quirky little bug, possibly related to the newer “fine-grained” invalidation mechanisms,...
View ArticleClik here to view.
Subquery Factoring (10)
What prompted me to write my previous note about subquerying was an upgrade to 12c, and a check that a few critical queries would not do something nasty on the upgrade. As ever it’s always interesting...
View ArticleClik here to view.
IN/EXISTS bugs
Here’s a simple data set – I’m only interested in three of the columns in the work that follows, but it’s a data set that I use for a number of different models: execute dbms_random.seed(0) create...
View ArticleClik here to view.
Result Cache
Yesterday I thought I’d spend half an hour before breakfast creating a little demonstration of a feature; some time about midnight I felt it was time to stop because I’d spent enough time chasing...
View ArticleClik here to view.
Histogram Limit
A surprising question came up on OTN a couple of days ago: Why does a query for “column = 999999999999999999” run slower than a query for “column > 999999999999999998” (that’s 18 digit numbers, if...
View ArticleClik here to view.
12c Downgrade
No, not really – but sometimes the optimizer gets better and gives you worse performance as a side effect when you upgrade. Here’s an example where 11.2.0.4 recognised (with a few hints) the case for a...
View ArticleClik here to view.
Invalidation
Someone who attended my sessions at the Bucharest Oracle Summit earlier on this year sent me an example of a quirky little bug, possibly related to the newer “fine-grained” invalidation mechanisms,...
View ArticleClik here to view.
Subquery Factoring (10)
What prompted me to write my previous note about subquerying was an upgrade to 12c, and a check that a few critical queries would not do something nasty on the upgrade. As ever it’s always interesting...
View ArticleClik here to view.
IN/EXISTS bugs
Here’s a simple data set – I’m only interested in three of the columns in the work that follows, but it’s a data set that I use for a number of different models: execute dbms_random.seed(0) create...
View ArticleClik here to view.
Result Cache
Yesterday I thought I’d spend half an hour before breakfast creating a little demonstration of a feature; some time about midnight I felt it was time to stop because I’d spent enough time chasing...
View Article