Working with and retrieving EXPLAIN table data
DB2® and certain optimization tools automatically populate EXPLAIN tables, such as PLAN_TABLE and DSN_STATEMNT_TABLE, but you might decide to modify or remove data from certain instances of these tables.
About this task
Recommendation: Because certain optimization tools depend on the data
in EXPLAIN tables, be careful not to manually modify data in EXPLAIN
table instances created for those tools.
You can enable column and row-level
access controls for EXPLAIN tables. However, the access controls do
not apply when DB2 inserts
data into the EXPLAIN tables.
- Retrieving EXPLAIN table rows for a plan
You can find the EXPLAIN table rows for all explainable statements of a particular plan in their logical order. - Retrieving EXPLAIN table rows for a package
You can retrieve the PLAN_TABLE rows for every explainable statement in a certain package. - Correlating information across EXPLAIN tables
When information about an SQL statement is captured into EXPLAIN tables, you can find relevant statistics and access path information from across the set of EXPLAIN tables. To find this information for a specific statement, use certain join predicates. - Columns for correlating EXPLAIN tables
You can use a set of standard columns to correlate records for a particular static SQL statement from different EXPLAIN tables. - Deleting EXPLAIN table rows
Although DB2 adds rows to EXPLAIN tables automatically. However, it does not automatically delete any rows from the tables.
Parent topic: Investigating SQL performance by using EXPLAIN
Related concepts: