A customer encountered a performance failure in its database system where a large number of transactions were congested. The direct cause was that CPU utilization reaches 100% on some OBServer nodes, which means that transactions cannot be processed normally. Based on the analysis of theGV$OB_SQL...
-- create database -- --- DROP database IF EXISTS `explain_test`; create database `explain_test` DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci; -- switch database use `explain_test`; -- --- -- table structurefor`tb_book` -- --- DROP TABLE IF EXISTS `tb_book`; ...
(6) index:the index tree is scanned, MySQL can use this type when the query uses only columns that are part of a single index. 表示全索引扫描(full index scan), 和ALL类型类似, 只不过ALL类型是全表扫描, 而index类型则仅仅扫描所有的索引, 而不扫描数据. mysql> explain select book_name from...
-databasedatabase-name 要说明的包所在数据库的名称。 为实现向后兼容,可以使用-d代替-database。 -useruser-idpassword 建立数据库连接时要使用的授权标识和密码。user-id和password都必须符合Db2®命名约定,并且必须可以由数据库识别。 为实现向后兼容,可以使用-u代替-user。 output-options: 这些选项指定db2ex...
why my services doen't write in database when calling them from components? I'm creating a delegate expression for a Camunda process the workflow works perfect but when it executes the delegate my services creates the objects and doesn't write them into the database. this is ... ...
In addition to supporting encryption at rest, SQL Server supports encrypting data within columns using Always Encrypted. Once data is encrypted, the application accessing the database must have the correct certificate in order to view the plain text values of the data. ...
Database Security Database Quick Start Development and Design Proposal Application Development Guide SQL Optimization SQL Reference GaussDB SQL Keywords Data Types Character Sets and Collations Constant and Macro Functions and Operators Expressions Pseudocolumn ...
You cannot usethe EXTENDED and PARTITIONS keywords together in the same EXPLAIN statement. In addition, neither of these keywordscan be used together with the FORMAT option. (FORMAT=JSON causesEXPLAIN to display extended and partition informationautomatically; using FORMAT=TRADITIONAL has no effect on...
Other than the system and const types, eq_ref is the best possible join type. The database will access one row from this table for each combination of rows from the previous tables. possible_keys - The optional indexes MySQL can choose from, to look up for rows in the table. Some of...
-i NAME name of serverinstance(ifusing mysql.server startup script)-l don't subtract lock time from total time windows支持软件安装完成 优化开始… … 查询lm_d_plan全表条数 mysql> use lms Database changed mysql> selectcount(*)from lm_d_plan; ...