Appears in a parallel execution plan
This operation was introduced in Oracle 8.1.5
This operation is implemented in the following versions
This operation has not yet been observed in Oracle 10.2.
This operation appears in the slave process of a parallel query. The execution plan is only generated if the query is executed, therefore it is not sufficient just to explain the query.
The execution plan can be observed in V$SQL_PLAN
This example was developed using Oracle 188.8.131.52 on Windows 2000
This example requires the following table definition
CREATE TABLE t1 (c1 NUMBER);
The table must have at least one row
INSERT INTO t1 VALUES (0);
The table does not need to be analysed
SELECT /*+ PARALLEL (t1,4) */ c1,COUNT(*) FROM t1 GROUP BY c1;
generates the following execution plan
0 SELECT STATEMENT Optimizer=CHOOSE 1 0 SORT (GROUP BY) 2 1 SORT (GROUP BY) 3 2 TABLE ACCESS (FULL) OF 'T1'
Step 1 executes the following SQL statement using slave processes
SELECT /*+ CIV_GB */ A1.C0,COUNT(SYS_OP_CSR(A1.C1,0)) FROM :Q86000 A1 GROUP BY A1.C0;
This generates the following execution plan
0 SELECT STATEMENT Optimizer=CHOOSE 1 0 SORT (GROUP BY) 2 1 TABLE QUEUE :Q86000