Appears in a parallel execution plan
This operation was introduced in Oracle 8.1.5
This operation is implemented in the following versions
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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 9.2.0.1 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
The statement
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