Between
Reading Richard Foote’s latest blog note about automatic indexing and “non-equality” predicates I was struck by a whimsical thought about how the optimizer handles “between” predicates. (And at the...
View ArticleCBO Example
A little case study based on an example just in on the Oracle-L list server. This was supplied with a complete, working, test case that was small enough to understand and explain very quickly.The user...
View ArticleOracle 19c Automatic Indexing: Non-Equality Predicates Part II (Let’s Spend...
In my previous post in this series, I discussed out Automatic Indexing currently does not consider Non-Equality predicates. Automatic Indexing will index columns based only on Equality predicates. So...
View ArticleIndex Hints
I’ve lost count of the number of times I’ve reminded people that hinting (correctly) is hard. Even the humble /*+ index() */ hint and its close relatives are open to misunderstanding and accidental...
View ArticleIndex Hints
At the end of the previous post on index hints I mentioned that I had been prompted to complete a draft from a few years back because I’d been sent an email by Kaley Crum showing the optimizer ignoring...
View ArticleOracle Database 19c Automatic Indexing: Invisible Indexes Oddity (Wild Eyed...
There have been a couple of “oddities” in relation to both Oracle Autonomous Databases and Automatic Indexing behaviour that I’ve seen frequently enough now (on Oracle 19.5.0.0.0) to make it worth a...
View ArticleOracle 19c Automatic Indexing: Function-Based Indexes? (No Plan)
I previously discussed how Automatic Indexing only currently supports Equality based predicates. The question I have today is does Automatic Indexing support function-based indexes? Let’s take a look....
View ArticleOracle 19c Automatic Indexing: Function-Based Indexes? Part II (If You Can...
In my previous post, I discussed how Automatic Indexing does not currently support creating an index based on a function or expression predicate, even if it’s an equality predicate. You must manually...
View ArticleAdaptive error
There’s a thread on the Oracle Database Forum at present where someone has supplied a script to create some data that’s guaranteed to reproduce wrong results (provided your system stats and optimizer...
View ArticleJoin Elimination redux
This note is a followup to a post from a few years back (originally dating further back to 2012) where I described an inconsistency that appeared when join elimination and deferrable constraints...
View Article
