Re: Index build order
- From: Nigel Thomas <nigel.cl.thomas@xxxxxxxxxxxxxx>
- To: Martin.Klier@xxxxxxxxxx, ORACLE-L <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 27 Jan 2009 09:02:58 +0000
Martin
It was the case in Oracle v5 / v6 (and for all I know may still be) that the
rule-based optimizer chose between possible indexes (all other things being
equal) on the basis of creation date (or at least, the sequence in the IND$
table) - probably because that affected the position of the index definition
in memory. Similarly, the order of visiting tables in an execution path
tended to be reverse lexical (in the last resort).
There must still be cases where "all other things (such as statistics) are
equal" and that there is some deterministic fallback mechanism for any
optimizer to decide what to do - such as picking the first object in the
dictionary cache. Depending on the mechanism, this may seem to support
observations such as this one.
Regards Nigel
2009/1/27 Martin Klier <Martin.Klier@xxxxxxxxxx>
> does the index build order matter in any way? There's rumor that the order
> in which indexes are built does affect query performance.
>
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