The RDB$WORKLOAD system table is an optional system table
    (similar to RDB$SYNONYMS and RDB$CATALOG_SCHEMA). It is created
    when the database attribute WORKLOAD COLLECTION IS ENABLED is
    specified on an SQL CREATE or ALTER DATABASE statement. Once
    created, this system table can never be dropped.

    The following table provides information on the columns of the
    RDB$WORKLOAD system table.

                                Data
    Column Name                 Type      Summary Description

    RDB$CREATED                 date vms  Time workload entry was
                                          created.
    RDB$LAST_ALTERED            date vms  Last time statistics were
                                          updated.
    RDB$DUPLICITY_FACTOR        bigint(7) Value ranges from 1.0 to
                                          table cardinality. Number
                                          of duplicate values for an
                                          interesting column group
                                          (RDB$FIELD_GROUP).
    RDB$NULL_FACTOR             integer(7) Value ranges from 0.0 to
                                          1.0. This is the proportion
                                          of table rows that have
                                          NULL in one or more columns
                                          of an interesting column
                                          group.
    RDB$RELATION_ID             integer   Base table identifier.
    RDB$FLAGS                   integer   Reserved for future use.
    RDB$FIELD_GROUP             char(31)  Contains up to 15 sorted
                                          column identifiers.
    RDB$SECURITY_CLASS          char(20)  Reserved for future use.