Re: Encoded Vector Indexes

[Russell Conerly <rconerly@xxxxxxxxxxx>]

David,
I analyzed the optimizer messages while in debug.  I've also explored several 
guides
in regards to performance of SQL, but I have been leery of making changes to 
the query
options file.  Any recommendations on those changes?

Thanks for your response.

Regards,
Russell Conerly


>Russell,
>
>Have you run this in debug and analyzed the performance messages?  Also, have
>you 
>gone through the optimization section of the SQL programming guide?  Have you 
>experimented with query options file (qaqqini) changes?  I would explore those
>options 
>before building indexes.
>
>In some cases an EVI will help a slow SQL statement.  Others have had better
>results, but 
>a 25% is about the best I have ever seen with an EVI.  The biggest improvements
>usually 
>come from normal indexes or by restructuring the statement.  On highly
>normalized files, the 
>structure of the statement can really change performance.  For example, 
>changing
>the primary 
>file, the source file for key fields, and intermediary joins, can all have a 
>big
>impact on performance.  
>Some other tricks are to build indexes over all selected fields if only a few
>are used. This last 
>one works best with things like customer name, customer number on a large
>customer file.
>
>David Morris
>
>
>
>>>> rconerly@netdoor.com 01/30/01 04:16PM >>>
>I have been doing some studying on Encoded Vector Indexes with SQL.  I've been
>looking at improving performance of an SQLRPGLE program running on V4R4 
>that is using some rather
>large files.  The documentation I have found has been limited IMO.
>
>Have any of you experimented with/used EVI's?  And if so, what are the 
>pros/cons to using
>them?  Does the optimizer inform you that it is using the EVI?  Do you use 
>the index
>in your select statement or is the index implied?  Please advise.
>
>Thank you in advance.
>
>Regards,
>Russell Conerly
>Artaban Solutions, Inc.
>
>
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