If I run the following Runstats command:
Runstats Database.tablespace Index(all)
will it update ALL columns
of a multi-column index or just the first column?
QUESTION POSED ON: 29 JUN 2004
QUESTION ANSWERED BY:
Craig Mullins
When you specify INDEX(ALL) without any other options DB2 will update
statistics only for the first column of each index defined on the tables in
the table space specified.
If you want to gather statistical information for additional index columns
you will need to specify other options.
The KEYCARD parameter tells RUNSTATS to collect all of the distinct values
in all of the 1 to n key column combinations for
the specified indexes. n is the number of columns in the index.
The NUMCOLS parameter can be used to indicate a specific number of key
columns to concatenate together when collecting
frequent values from the specified index. For example, specifying three means to
collect frequent values on the concatenation of the first three key columns.
The default is 1, which means collect frequent values on the first key
column of the index. For More Information
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