/+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 ...
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...
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 ...
Beginning with Oracle Database 11g Release 2 (11.2.0.1), the PARALLEL and NO_PARALLEL hints are statement-level hints and supersede the earlier object-level hints: PARALLEL_INDEX, NO_PARALLEL_INDEX, and previously specifie...
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...
For example,GROUPBY,NOTIN,SELECTDISTINCT,UNION,UNIONALL,CUBE, andROLLUP, as well as aggregate and table functions. The Parallel Execution Server Pool When an instance starts up, Oracle creates a pool of parallel execution servers which are available for any parallel operation. The initialization par...
For example, if your system has 20 CPUs and you issue a parallel query on a table that is stored on 15 disk drives, then the default degree of parallelism for your query is 15 query servers. Note: Oracle obtains the information about disks and CPUs from the operating system. ...
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...
Optimizer hints MyISAM temporary tables EXPLAIN statement As shown in examples throughout this section, the EXPLAIN statement indicates whether each stage of a query is currently eligible for parallel query. It also indicates which aspects of a query can be pushed down to the storage layer. Th...
It’s a question that crops up from time to time, usually followed by a list of reasons why it shouldn’t have gone parallel – no hints in the query, table is not declared parallel, parallel_degree_policy is set tomanualetc.