DSN1COMP output

The output of the DSN1COMP utility lists a variety of information.

Message DSN1941

If you receive this message, use a data set with more rows as input, or specify a larger ROWLIMIT.

Sample DSN1COMP report

The following figure shows a sample of the output that DSN1COMP generates.

Figure 1. Sample DSN1COMP report

DSN1940I DSN1COMP COMPRESSION REPORT
             301  KB WITHOUT COMPRESSION
             224  KB WITH COMPRESSION
              25  PERCENT OF THE BYTES WOULD BE SAVED
 
           1,975  ROWS SCANNED TO BUILD DICTIONARY
           4,665  ROWS SCANNED TO PROVIDE COMPRESSION ESTIMATE
           4,096  DICTIONARY ENTRIES
 
              81  BYTES FOR AVERAGE UNCOMPRESSED ROW LENGTH
              52  BYTES FOR AVERAGE COMPRESSED ROW LENGTH
 
              16  DICTIONARY PAGES REQUIRED
             110  PAGES REQUIRED WITHOUT COMPRESSION
              99  PAGES REQUIRED WITH COMPRESSION
              10  PERCENT OF THE DB2 DATA PAGES WOULD BE SAVED

Example of DSN1COMP on an index

The following figure shows an example of the output that DSN1COMP on an index generates.

Figure 2. Sample DSN1COMP output

DSN1999I START OF DSN1COMP FOR JOB DSN1COMP STEP2
DSN1998I INPUT DSNAME = TESTCAT.DSNDBD.DB1COMPR.I1.I0001.A001       , VSAM

DSN1944I DSN1COMP INPUT PARAMETERS
                  PROCESSING PARMS FOR INDEX DATASET:
                  NO LEAFLIM WAS REQUESTED

DSN1940I DSN1COMP COMPRESSION REPORT

              38  Index Leaf Pages Processed
           3,000  Keys Processed
           3,000  Rids Processed
             401  KB of Key Data Processed
             106  KB of Compressed Keys Produced


                  EVALUATION OF COMPRESSION WITH DIFFERENT INDEX PAGE SIZES:

                  ----------------------------------------------
               8  K Page Buffer Size yields a
              51  % Reduction in Index Leaf Page Space
                  The Resulting Index would have approximately
              49  % of the original index's Leaf Page Space
                  No Bufferpool Space would be unused
                  ----------------------------------------------

                  ----------------------------------------------
              16  K Page Buffer Size yields a
              74  % Reduction in Index Leaf Page Space
                  The Resulting Index would have approximately
              26  % of the original index's Leaf Page Space
               3  % of Bufferpool Space would be unused to
                  ensure keys fit into compressed buffers
                  ----------------------------------------------


DSN1994I DSN1COMP COMPLETED SUCCESSFULLY,             38  PAGES PROCESSED