SYSSTATFEEDBACK catalog table

The SYSSTATFEEDBACK table contains information about missing or conflicting catalog statistics for SQL statements. The schema is SYSIBM.

The following values control the collection of statistics feedback data in the SYSSTATFEEDBACK catalog table:

  • The STATFDBK_SCOPE subsystem parameter controls whether the data is collected, and whether it is collected only for static SQL statements, only for dynamic SQL statements, or for both.
  • The STATSINT subsystem parameter controls when and how frequently the data is externalized.
  • The STATS_FEEDBACK column of the SYSTABLES catalog table controls whether the data is collected for a particular table.

The RUNSTATS utility removes data from the SYSSTATFEEDBACK catalog table when the recommended statistics are collected.

Tip: Start of changeThe SYSSTATFEEDBACK table might contain rows that recommend collection of statistics for DEFINE NO objects, or empty table space partitions. However, statistics cannot be collected for such objects until after data is inserted and the underlying data sets are created. For more information, see Effect of utilities on objects that have the DEFINE NO attribute.End of change
Table 1. SYSIBM.SYSSTATFEEDBACK table column descriptions
Column name Data type Description Use
TBCREATOR VARCHAR(128) The creator of the table. S
TBNAME VARCHAR(128) The name of the table. S
IXCREATOR VARCHAR(128) The creator of the index. S
IXNAME VARCHAR(128) The name of the index. S
COLNAME VARCHAR(128) The name of the column. S
NUMCOLUMNS SMALLINT The number of columns in the column group. S
COLGROUPCOLNO VARCHAR(254) FOR BIT DATA A hex representation that identifies the set of columns associated with the statistics. If the statistics are only associated with a single column, the field contains a zero length. Otherwise, the field is an array of SMALLINT column numbers with a dimension equal to the value in NUMCOLUMNS. S
TYPE CHAR(1) The type of statistic to collect:
'C'
Cardinality.
'F'
Frequency.
'H'
Histogram.
'I'
Index.
'T'
Table.
 I
DBNAME VARCHAR(24) The name of the database. S
TSNAME VARCHAR(24) The name of the table space. S
REASON CHAR(8) The reason for the statistics collection recommendation:
'BASIC'
A basic statistical value for a column table or index is missing.
'CONFLICT'
Another statistic conflicts with this statistic.
'COMPFFIX'
Multi-column cardinality statistics are needed for an index compound filter factor.
'DEFAULT'
A predicate references a value that is probably a default value.
'KEYCARD'
The cardinalities of index key columns are missing.
'LOWCARD'
The cardinality of the column is a low value, which indicates that data skew is likely.
'NULLABLE'
Distribution statistics are not available for a nullable column.
Start of change'RNGPRED'End of change
Histogram statistics are not available for a range predicate.
'PARALLEL'
Parallelism could be improved by uniform partitioning of key ranges.
Start of change'STALE'End of change
Start of changeA statistic appears likely to be out of sync with other statistics, based on comparison of the time that it was collected to statistics collection times for related objects.End of change
 S
BLOCK_RUNSTATS CHAR(1) Whether the row is used when optimization tools collect statistics based on the recommendations. Db2 inserts a blank value in this column for all new rows. Db2 does not refer to or change the value of this column. This is an updatable column. S
REMARKS VARCHAR(254) Free form text for extensibility. S
LASTDATE DATE The last date that this statistics recommendation was updated by Db2. S