Indexes not used

Peter Vanroose

Indexes not used
On Wed, 31 Dec 2008 Vanitha_Subramaniam wrote:
> Is there a way that we can assure that the indexes are not used for accessing

From your list of unused indexes, be sure to remove the "CLUSTER" indexes
and the "UNIQUE" indexes. Paraphrasing Avram, I would also remove the
indexes defined on Foreign Key columns, since they could be used (without
EXPLAIN telling you) when a PK is deleted.

Also be aware that indexes may carry useful information for the optimizer,
even without them being used: index statistics (e.g., cluster ratio or key
cardinality) are actually table statistics which influence the cost
calulation and hence the access path chosen, even when the particular index
is not part of the ultimate access path.


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