Software Platform User guide

grouping, sorting, or formatting of the report doesn't change at all. The indexes
merely allow Crystal Reports to locate particular records quickly, without
passing through the saved data in its entirety.
Considerations for using Saved Data Indexes
There are some things that you should consider before deciding to use Saved
Data Indexes:
• Indexes work best in scenarios where a report contains a large set of
data, but only small subsets of the data are viewed at one time.
• Large, complex reports can overload the Crystal Reports report engine.
For example, creating a large report with a selection formula that returns
90% of the report's data will probably take up more memory and disk
space than a report file without indexes. In such a case, report processing
will be slower.
• Indexes require disk space; this disk space can add up to more than the
space required for the data itself. You trade the speed of applying selection
formulas for the size of your report files.
• The Crystal Page and RAS servers are limited in how much caching
occurs for different users when selection formulas are applied. Therefore,
when a user views a report file with a selection formula and the Page
Server takes up a certain amount of RAM, adding more users could cause
the Page Server to use even more RAM.
Indexing the right field(s)
These guidelines describe the best ways to index saved data and what to
avoid when indexing:
• Index fields that users frequently add to their record selection formulas.
• Index fields that are referred to by the report's record selection formula.
• Don't index all of the fields in the report.
Doing so can result in increased processing times. It is best to index only
on the fields that meet the criteria specified above. If all of the fields meet
Crystal Reports 2008 SP3 User's Guide 713
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Understanding Databases
Saved Data Indexes