User`s guide

In a worst case scenario the program would have to read about 67,600 records to accomplish the
same task.
Note:
The performance considerations for data files are different from the considerations for SQL databases.
A data file is any non-SQL database that is accessed directly from Crystal Reports. For the purpose of
this discussion, an SQL database is any database capable of accepting SQL commands accessed
directly from Crystal Reports or through ODBC as well as any other database types that are accessed
through ODBC.
For a better understanding of the difference between direct access databases and ODBC data sources,
see Accessing Data Sources in the online help.
23.5.3.1 Extended descriptions of chart columns
The performance charts use the following columns:
• Linking or Subreport
Are you creating a report from linked databases or are you inserting a subreport and binding it to
the data in your primary report?
• Selection Formula
Does your primary report include a record selection formula that sets range limits on the key (indexed)
field in Table A?
• Index A
Is Table A on the field you are going to use indexed to match up the records?
• Index B
Is Table B on the field you are going to use indexed to match up the records?
• Reads A
How many records does the program have to read out of Table A to find the two records it is looking
for?
• For each A reads in B
How many records does the program have to read in Table B to find the 200 records it is looking
for?
• Total Records Read
What is the total number of records the program has to process to complete the task?
2012-03-14522
Understanding Databases