OS & Oracle

The PQ_DISTRIBUTE hint instructs the optimizer how to distribute rows of joined tables among producer and consumer query servers. Such distribution can improve the performance of parallel join operations.
 
tablespec is the name or alias of a table to be used as the inner table of a join. [...]

Two execution plans.
Disable optimizer_dynamic_sampling firstly.

alter session set optimizer_dynamic_sampling = 0;

Then, create two simple tables;

CREATE TABLE t1 ( c1 NUMBER, c2 NUMBER );
CREATE TABLE t2 ( c1 NUMBER, c2 NUMBER );

hr@ORCL> SELECT /*+ parallel(t1,2) */ t1.c2,t2.c2 FROM t1,t2 WHERE t1.c1 = t2.c1;

Execution Plan
———————————————————-
Plan hash value: 869483324

——————————————————————————————————————
| Id | Operation [...]