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Maximizing ADABAS Performance

Among the factors that affect ADABAS performance are the size of the file being accessed, the number of data fields being accessed, and the number of logical records qualified by the selection criteria. For files that have many data fields and many logical records, you should evaluate all SAS programs that need to access the data directly. In your evaluation, consider the following questions:

• Do the selection criteria allow ADABAS to use ADABAS descriptor data fields efficiently? See Creating and Using View Descriptors Efficiently for some guidelines on specifying efficient selection criteria.

• Does the program need all the ADABAS data fields? If not, create and use an appropriate view descriptor that includes only the data fields to be used.

• Do the selection criteria retrieve only those logical records needed for subsequent analysis? If not, specify different conditions so that the selected data are restricted for the program being used.

• Are the data going to be used by more than one procedure in a single SAS session? If so, consider extracting the data and placing them in a SAS data file for SAS procedures to use, instead of allowing the data to be accessed directly by each procedure. See Performance Considerations for circumstances when extracting data is the more efficient method.

• Do the data need to be in a particular order? If so, include a SORT clause in the appropriate view descriptor or a SAS BY statement in the SAS program.

• What kind of locking mechanism will ADABAS need to use? See Controlling Data Locks.

• Are you using a view SORT clause, a SAS BY statement, or a SAS ORDER BY clause without either a view WHERE clause or a SAS WHERE clause? Without a WHERE clause, the engine qualifies all ADABAS data to be sorted, which can use a considerable amount of resources.

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