BUFFER (SORT) Description Performs a memory sort on a row source CREATE TABLE t1 (c01 NUMBER); CREATE INDEX T1_C1 ON T1(C01); CREATE TABLE t2 (c02 NUMBER); BEGIN DBMS_STATS.GATHER_TABLE_STATS(ownname => 'SCOTT', tabname => 'T1', estimate_percent => 30, method_opt => 'for all columns size repeat', no_invalidate => FALSE, degree => 8, cascade => TRUE); END; BEGIN DBMS_STATS.GATHER_TABLE_STATS(ownname => 'SCOTT', tabname => 'T2', estimate_percent => 30, method_opt => 'for all columns size repeat', no_invalidate => FALSE, degree => 8, cascade => TRUE); END; SQL> set autot trace SQL> SELECT t1.c01, t2.c02 FROM t1,t2; Execution Plan ---------------------------------------------------------- Plan hash value: 787647388 ----------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ----------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | 26 | 4 (0)| 00:00:01 | | 1 | MERGE JOIN CARTESIAN| | 1 | 26 | 4 (0)| 00:00:01 | | 2 | TABLE ACCESS FULL | T1 | 1 | 13 | 2 (0)| 00:00:01 | | 3 | BUFFER SORT | | 1 | 13 | 2 (0)| 00:00:01 | | 4 | TABLE ACCESS FULL | T2 | 1 | 13 | 2 (0)| 00:00:01 | -----------------------------------------------------------------------------