parallel_threads_per_cpu integer 2 resource_manager_cpu_allocation integer 8 SQL> 以下有三个参数返回: cpu_count : 表示cpu数 parallel_threads_per_cpu :表示每个cpu允许的并行进程数 resource_manager_cpu_allocation :该参数决定 Resource Manager 可以利用的CPU数,该参数已弃用,仅作向后兼容。 参考资料: Oracle参数解析(resource_manager_cpu_al...
Parallel Combined with parent(PCWP): Parallel Combined with Child(PCWC): Serial to Parallel ( S->P ) : 一个串行操作发送数据给并行操作,如果select 部分是串行操作,就会出现这个情况。 并行度的设定 (1)在语句中,使用Hint 指定并行度。 (2)使用alter session force parallel 设定并行度。 (3)使用SQL中...
select /*+ parallel(emp,4)*/ * from emp where deptno=200 and sal>300; 另:每个SELECT/INSERT/UPDATE/DELETE命令后只能有一个/*+ */,但提示内容可以有多个,可以用逗号分开,空格也可以。 如:/*+ ordered index() use_nl() */ Thanks and Regards 参考: Oracle MetaLink Hint用法 & OTN...
32. parallel select /*+ parallel(emp,4)*/ * from emp where deptno=200 and sal>300; 另:每个SELECT/INSERT/UPDATE/DELETE命令后只能有一个/*+ */,但提示内容可以有多个,可以用逗号分开,空格也可以。 如:/*+ ordered index() use_nl() */ Thanks and Regards 参考: Oracle MetaLink Hint...
如果不使用函数,使用普通的SQL,又是可以使用HINT强制并行的,如下: 15:59:07 SYS@orcl> select /*+ parallel */ a||','||b from big_data; 已选择999999行。 已用时间: 00: 00: 04.09 执行计划 --- Plan hash value: 2638980575 ---
{DELETE|INSERT|SELECT|UPDATE} --+ hint [text] [hint[text]]... 如果语(句)法不对,则ORACLE会自动忽略所写的HINT,不报错 二、具体分析 1. /*+ALL_ROWS*/ 表明对语句块选择基于开销的优化方法,并获得最佳吞吐量,使资源消耗最小化. 例如:
ThePARALLEL_ENABLEoption declares that a stored function can be used safely in the slave sessions of parallel DML evaluations. The state of a main (logon) session is never shared with slave sessions. Each slave session has its own state, which is initialized when the session begins. The func...
在会话级别,可以使用下面的SQL语句启用或禁用并行查询: ALTER SESSION ENABLE PARALLEL QUERY ; ALTER SESSION DISABLE PARALLEL QUERY ; 另外,还可以通过使用下面的SQL语句来启动并行查询,并同时覆盖表或索引级别定义的并行度: ALTER SESSION FORCE PARALLEL QUERY PARALLEL 4; 需要注意的是:提示可以覆盖会话级别的设置...
This was run in up to 100 parallel sessions using dbms_scheduler jobs until approximately 1 million rows were inserted. The code for this test can be found in the appendix section “Testscript 2 – code”. Because of the 1 sec. pause this will run for some time. Index stats after ...
Imagine if you went to the grocery store and only one person was allowed in at a time. Everyone else had to wait outside in a long line until each individual completed their trip before entering the store. Even worse, image if you were only allowed to buy one item while inside the ...