The join key column QQKEY simplifies the joining of multiple tables together. This column replaces the join field (QQJFLD) and unique query counters (QQCNT) that the database monitor used. The join key column contains a unique identifier that allows all of the information for this query to be received from each of the tables.
This join key column does not replace all of the detail columns that are still required to identify the specific information about the individual steps of a query. The Query Definition Template (QDT) Number or the Subselect Number identifies information about each detailed step. Use these columns to identify which rows belong to each step of the query process:
Use these columns when the monitored query contains a subquery, union, or a view operation. All query types can generate multiple QDT's to satisfy the original query request. The server uses these columns to separate the information for each QDT while still allowing each QDT to be identified as belonging to this original query (QQKEY).