View Explain

To show the Explain Plan of the query, click Explain on the toolbar. If the query statement is correct, the Explain tab opens with the columns in the PLAN_TABLE.

Column
Description
Operation Name of the internal operation performed in this step.
Object Name of the table or index.
Optimizer

Current mode of the optimizer.

Cost

Cost of the operation as estimated by the optimizer's query approach. Cost is not determined for table access operations. The value of this column does not have any particular unit of measurement; it is merely a weighted value used to compare costs of execution plans. The value of this column is a function of the CPU_COST and IO_COST columns.

Cardinality

Estimate by the query optimization approach of the number of rows accessed by the operation.

Bytes

Estimate by the query optimization approach of the number of bytes accessed by the operation.

Partition Start

Start partition of a range of accessed partitions.

Partition ID

Step that has computed the pair of values of the PARTITION_START and PARTITION_STOP columns.

Access Predicates

Predicates used to locate rows in an access structure. For example, start or stop predicates for an index range scan.

Filter Predicates

Predicates used to filter rows before producing them.