Re: Index build order

From: Nigel Thomas <>
Date: Tue, 27 Jan 2009 09:02:58 +0000
Message-ID: <>


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 <>

> does the index build order matter in any way? There's rumor that the order
> in which indexes are built does affect query performance.

Received on Tue Jan 27 2009 - 03:02:58 CST

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