Select the actions on this page in order.

This step checks to see how close the estimated compressed size is to the actual.

Get actual compressed size

The first step collects statistics for the CUSTOMER_ADDRESS_WITH_COMPRESSION table and retrieves an estimate of the the table size. The SQL used to collect statistics and determine the table size are:


CALL ADMIN_CMD
  ('RUNSTATS ON TABLE CUSTOMER_ADDRESS_WITH_COMPRESSION')

SELECT CAST(CAST(NPAGES AS DOUBLE)/256
  AS DECIMAL(5,3))
  FROM SYSIBM.SYSTABLES
    WHERE CREATOR=?SCHEMA?
      AND NAME='CUSTOMER_ADDRESS_WITH_COMPRESSION'

Compare table sizes

The second step plots the current table size, the estimated table size (in MB) and the actual compressed size on a bar graph.

If you hover your cursor over the bars in the graph you will see the exact sizes of each table. Notice how well the estimate predicted the actual size of the compressed table.