Runstats statistics about sub-elements

The runstats utility attempts to collect statistics for columns of type BINARY, VARBINARY, CHAR, and VARCHAR with a code page attribute of single-byte character set (SBCS), FOR BIT DATA, or UTF-8 when you specify the LIKE STATISTICS clause.

The runstats utility might decide not to collect the statistics if it determines that such statistics are not appropriate after analyzing column values.

SUB_COUNT: The average number of sub-elements.
SUB_DELIM_LENGTH: The average length of each delimiter separating the sub-elements. A delimiter, in this context, is one or more consecutive blank characters.

To examine the values of the sub-element statistics, query the SYSCAT.COLUMNS catalog view. For example:

   select substr(colname, 1, 16), sub_count, sub_delim_length
     from syscat.columns where tabname = 'DOCUMENTS'

The RUNSTATS utility might take longer to complete if you use the LIKE STATISTICS clause. If you are considering this option, assess the improvements in query performance against this additional overhead.