db-derby-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Oystein.Grov...@Sun.COM (Øystein Grøvlen)
Subject Re: How to update cardinality statistics
Date Wed, 19 Oct 2005 09:04:47 GMT
>>>>> "MM" == Mike Matrigali <mikem_app@sbcglobal.net> writes:

    MM> I 2nd Satheesh's query, it is useful to know why you care.  Derby
    MM> unlike most other database's automatically maintains histogram
    MM> type information about the tables (this does require indexes to
    MM> exist).  This information is gathered directly from the indexes,
    MM> and is automatically maintained by Derby.

    MM> The row count is also automatically maintained by Derby - whether
    MM> an index exists or not.

Sounds good, but I think read somewhere in the Derby documentation
that some statistical information was only updated when a query did a
sequential scan of the table.  


View raw message