about encoded vector index

about encoded vector index

Post by sergio davin » Tue, 17 Aug 1999 04:00:00



we are trying to use EVI on OS/400 (v4r3m0  ptf TL99054) but we can't
we have a file with about 1,000,000 records, and we have built two evi.. one
on a field with 5 distinct values and the other on a field with 200 distinct
values.. but all the queries that we run, (with combination of these fields
or with a single field) don't use this indexes.. (with debug... reason code
4)
are we making something wrong? or is it a missing ptf?

thank you to everybody

Sergio

(sorry for my bad english)

 
 
 

about encoded vector index

Post by Kent Milliga » Wed, 18 Aug 1999 04:00:00


The optimizer has obviously determined that it's more efficient to use
something other than the EVI to implement the query.  It really depends.

I'd suggest taking the DB2 SQL & Query Performance Monitoring and Tuning
class to better understand when & how EVI's are used by DB2.  The course
number is S6140.  You can find a link at:
        http://www.as400.ibm.com/db2/db2educ_m.htm

--
Kent Milligan, DB2 & Business Intelligence team
AS/400 Partners In Development

(opinions stated are not necessarily those of my employer)

 
 
 

1. EVI (Encoded Vector Index) --- experiences

I would like to know what experiences you have with Encoded Vector
Indexes (EVI).

What to do and especially what not to do. What problems have you
encountered ? Good or bad performance.

In the system I'm supporting there is a physical file with 35 mill.
records and 24 indexes !!! (No I didn't create them.) Each index has a
size between 500 and 750 Mb. I have an idea that EVIs can be used
instead to both reduce the amount of storage used and even improve
performance.

But before I recommend creating EVIs I would like to hear from you
first.

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