PARALLEL_FORCE_LOCAL控制Oracle RAC环境下的并行执行。默认情况,被选择执行一个SQL语句的并行服务器进程能在簇中任何或所有Oracle RAC节点上操作。通过设置PARALLEL_FORCE_LOCAL为true,并行服务器进程被限制从而都在查询协调器驻留的同一个Oracle RAC节点上操作(语句被执行的节点上) 。 PARALLEL_MIN_PERCENT 参数类型 I...
/+INDEX_ASC(TABLE INDEX_NAME) parallel(emp,4)*/ 2.如果表有别名,则写别名,否则不会走Hints优化。 Select /*+ parallel(e,4)*/ --- 会走Hints优化; * from emp e where deptno=200 and sal>300; Select /*+ parallel(emp,4)*/ --- 不会走Hints优化; * from emp e where deptno=200 and ...
Beginning with Oracle Database 11gRelease 2 (11.2.0.1), thePARALLELandNO_PARALLELhints are statement-level hints and supersede the earlier object-level hints:PARALLEL_INDEX,NO_PARALLEL_INDEX, and previously specifiedPARALLELandNO_PARALLELhints. ForPARALLEL, if you specifyinteger, then that degree of ...
PARALLEL_ADAPTIVE_MULTI_USER, when set to true, enables an adaptive algorithm designed to improve performance in multiuser environments that use parallel execution. The algorithm automatically reduces the requested degree of parallelism based on the system load at query startup time. The effective degre...
目前了解的情况是与CPU核数过高、数据库的并行参数(paraller_max_server)设置过高(256)等有关,ORACLE的算法在低版本有BUG(在cpu核数超过128、并行参数设置过高时容易触发)。 Alert日志显示在进行一个insert语句时触发了该bug引起宕机。之后重启时由于并行恢复参数设置问题,同样触发了BUG,导致无法启动。经查询metalink...
Oracle should respond with output similar to: NAME SUM(BYTES)--- ---PX msg pool 1474572free memory 562132---20367043 rows selected. To resolve this, increase the value for LARGE_POOL_SIZE. This example shows the LARGE_POOL_SIZE to be about 2MB. Depending on the amount of memory available...
Oracle ignores parallel hints on temporary tables. Refer to CREATE TABLE and Oracle Database Concepts for more information on parallel execution. See Also: CREATE TABLE and Oracle Database Concepts for more information on parallel ...
For a specific query, place the MERGE_AJ or HASH_AJ hints into the NOT IN subquery. MERGE_AJ uses a sort-merge anti-join and HASH_AJ uses a hash anti-join. For example: SELECT * FROM empWHERE ename LIKE 'J%' ANDdeptno IS NOT NULL ANDdeptno NOT IN (SELECT /*+ HASH_AJ */ dep...
using parallel DML, no other query or DML statement (whether serial or parallel) can access the same table in that transaction. Oracle will generate an error if you try to access any table that has been modified previously, in the same transaction, using parallel DML. Here is an example: ...
Using hints or the PARALLEL clause Object level Found in the definition of the table, index, or other object Instance level Using default values for the instance Oracle determines the degree of parallelism to use for a SQL statement by checking each item in this list in the order show...