Estimating Compression Savings
It can be advantageous to estimate the savings that could be gained by using the compression techniques available in DB2 UDB v8.1 without creating, altering, or loading a table.
We have provided you with a query that you can download from the Web that makes a rough estimate of the cost benefit of activating value compression (npage_ohead_est in the result set of the query) and system default compression (new_npage_est in the result set of the query) on columns where most or all values are defaults. This query is available at: http://authors.phptr.com/zikopoulos/
This query is completely dependent on the accuracy of the distribution statistics—the more up to date that information is, the better chance this query ...
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