Collecting correlation statistics

Use the Index Correlation Statistics window to specify setting for frequent value statistics

Authorities and privileges

To collect correlation statistics:

  1. To open the Index Correlation Statistics window, click the Add button on the Indexes page of the Index Statistics window.
  2. Specify the Collect key cardinalities check box to collect all of the distinct values in all of the 1 to n key column combinations for the specified indexes, where  n is the number of columns in the index.
  3.  To collect frequent value statistics, click the Add push button and type values in the Frequent values statistics options table:
  4. Number of Columns
    Indicates the number of key columns to concatenate together when collecting frequent values from the specified index. Specifying '3' means to collect frequent values on the concatenation of the first three key columns.
    Number of frequent values
    Indicates the number of frequent values to be collected. Specifying '15' means collect 15 frequent values from the specified key columns.
  5. Click OK.