Using index condition是MySQL 5.6中引入的一种新特性,叫做Index Condition Pushdown(ICP),是一种在存储引擎层使用索引过滤数据的一种优化方式。这里的“下推” 是指将原来在server层进行的table filter中可以进行index filter的部分,在引擎层面使用index filter进行处理,不再需要回表进行
1.测试联合索引的最左原则的时候, 发现了5.6版本后的新特性Index Condition Pushdown 2.含义就是存储引擎层根据索引尽可能的过滤数据,然后在返回给服务器层根据where其他条件进行过滤 3.比如我有这样的联合索引 KEY `name_gid_age_index` (`name`,`gid`,`age`) , 查询的时候where name='taoshihan' and age...
MySQL执行计划中的Extra中信息非常多,不仅仅包括Using index,Using where Using index,Using index condition,Using where,尤其是在多表连接的时候,这一点在相对MSSQL来说,不够直观或者结构化。 MSSQL中是通过区分索引查找(index seek),索引扫描(index scan),表扫描(table scan)来实现具体的查询的,这图形化的执行...
Bug #41136 ORDER BY + range access:EXPLAIN shows "Using MRR" while MRR is actually not used Submitted: 30 Nov 2008 14:32Modified: 23 Nov 2010 3:34 Reporter: Sergey Petrunya Email Updates: Status: Closed Impact on me: None Category: MySQL Server: OptimizerSeverity: S3 (Non-critical)...
alternatives":[{"index":"PRIMARY","ranges":["b <= id <= c"]/* ranges */,"index_dives_for_eq_ranges":true,"rowid_ordered":true,"using_mrr":false,"index_only":false,"rows":2,"cost":2.41,"chosen":true}]/* range_scan_alternatives */,"analyzing_roworder_intersect":{"usable":...
Bug #42991 invalid memory access and/or crash when using index condition pushdown + innodb Submitted: 18 Feb 2009 19:59Modified: 14 May 2011 1:43 Reporter: Shane Bester (Platinum Quality Contributor) Email Updates: Status: Closed Impact on me: None Category: MySQL Server: OptimizerSeverity...
Taguchi L27 orthogonal array is used to model the turning process and analyze the factors (cutting speed, depth of cut and feed rate) on material removal rate, MRR, surface roughness, SR and circularity error, CE. Further, attempts are made to optimize the sustainability index taken into ...
The number of theoretical and empirical literature on Industry 4.0 research has seen tremendous growth over the past few years. We seek to identify and classify the popular research topics published on Industry 4.0 in business and economics literature us
Table5presents the mean relative reduction in standard error (MRRSE, %) and coverage rate (CR, %) for the model-based estimators at the four administrative levels under consideration, providing insight into the uncertainty of the model-based estimates. The performance of the developed models also...
Only one subject, ID3, reported an increase of 1 point with respect to the pre-treatment condition. Such increase may be related to the intense mobilization per se, and not specifically to the use of the device, due to the presence of scars on the palm that may be stretched during the ...