At 10:23 AM 10/31/2012, [email protected] wrote:
... we often search where the field is not null or null. Do indexes
help with a "is null"?
And if they would, I assume I would decide whether to index based on
how many are null; if
50% are null then an index probably wouldn't help but if only 5% are
null then it might.
When evaluating the performance and retrieval of Indexed column(s),
there are two important
factors to consider.
01. Duplicate Factor
02. Adjacency Factor
Did you know that Data Designer in R:BASE eXtreme 9.1/9.5 include the
"Duplicate Factor" and
"Adjacency Factor" gauges to illustrate the status of Indexed
column(s) based on currently
stored records in table?
Database Explorer | Tables | Design Table | Data Designer | Keys/Indexes ...
For complete details and more, take a look at the "Indexing
Explained", a technical document
available at:
From The Edge: http://www.razzak.com/fte/
Topic: Indexing Explained
Date Posted: April 9, 2012
Have fun!
Very Best R:egards,
Razzak.
www.rbase.com
www.facebook.com/rbase
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