倒数第二段，MySQL has no limit on the number of tables. The underlying file systemmay have a limit on the number of files that represent tables.Individual storage engines may impose engine-specific constraints.InnoDB permits up to 4 billion tables.告诉你，表的建立是有限制的，如果使用InnoDB 存储...
数据备份不仅仅是开发、运维需要了解、熟练和掌握,一些架构设计或系统设计也需要熟练掌握,以备不时之需。最多的应用应该是编制文档上面的技术方案或者安全方案中涉及。 逻辑备份参数选项 从上一篇文章中,可以得到逻辑备份的格式如下: mysqldump [options] db_name[tbl_name...] mysqldump [options] --databases db_...
concat( round( ( data_length+index_length )/(1024*1024*1024),6),' G')AS'Total'FROMinformation_schema.TABLES WWHEREtable_schemaLIKE'database name'; 3、查看表空间 # 单位GBSELECTconcat( round(sum( data_length )/(1024*1024*1024),6),'GB')AS'Total Data Size'FROMinformation_schema.TABLESW...
TABLES 提供有关数据库中表的信息 TABLE_CONSTRAINTS 描述了哪些表具有约束 TRIGGERS 提供有关触发器的信息 VIEWS 提供有关数据库中的视图的信息 VIEW_ROUTINE_USAGE (从MySQL 8.0.13开始可用)提供对视图定义中使用的存储函数的信息的访问。该表未列出有关定义中使用的内置SQL函数或用户定义函数(UDF)的信息。 VIEW...
读取全量数据时,Source不需要获取全局读锁(FLUSH TABLES WITH read lock)。 如果您希望Source支持并发读取,每个并发的Reader需要有一个唯一的服务器ID,因此server-id必须是5400-6400这样的范围,并且范围必须大于等于并发数。 scan.incremental.snapshot.chunk.size 每个chunk的大小(包含的行数)。 否 INTEGER 8096 当开...
Upgrades from MySQL 8.0 are supported even if there are tables containing foreign keys referring to non-unique or partial keys. In such cases, the server writes a list of warning messages containing the names of any foreign keys which refer to nonstandard keys. Features...
这里,我们用一个select语句取出初始数据,通过一些计算,用update语句将新值更新到表中。包含有WRITE关键字的LOCKTABLE语句可以保证在UNLOCKTABLES命令被执行之前,不会有其它的访问来对inventory进行插入、更新或者删除的操作。 6、使用外键 锁定表的方法可以维护数据的完整性,但是它却不能保证数据的关联性。这个时候我们就...
A TEXT column with a maximum length of 4,294,967,295 or 4GB (232 − 1) characters. The effective maximum length is less if the value contains multibyte characters. The effective maximum length of LONGTEXT columns also depends on the configured maximum packet size in the client/server proto...
the range optimizer for tables with such dependencies. */ MAYBE_KEY, /** There is a range condition that can be used on this index. The range conditions for this index in stored in the SEL_ARG tree. */ KEY_RANGE } type; SEL_ARG *root; // The root node of the tree ...
Run themysqldserver as the user having the nameuser_nameor the numeric user IDuser_id. (“User”in this context refers to a system login account, not a MySQL user listed in the grant tables.) If you executemysqld_safewith the--defaults-fileor--defaults-extra-fileoption to name an opt...