(1) SQL如果创建时候,不指定类型那么默认是非聚集索引 (2) 聚集索引和非聚集索引都可以有重复记录,唯一索引不能有重复记录。 (3) 主键 默认是加了唯一约束的聚集索引,但是也可以在主键创建时,指定为唯一约束的非聚集索引,因此主键仅仅是默认加了唯一约束的聚集索引,不能说主键就是加了唯一约束的聚集索引 有点拗...
Re: Add index for mysql table with ndbcluster storage engine 867 urgen sherpa June 10, 2016 05:40AM Sorry, you can't reply to this topic. It has been closed. Content reproduced on this site is the property of the respective copyright holders. It is not reviewed in advance by Oracle an...
create unique index index_name on table_name('column_name'); 两者区别: (1)add index_name 支持一次多个索引创建alter table table_name add index_name using btree('column_name',...,'column_name'),add index_name using btree('column_name',...,'column_name') (2)add index_name 可以创建 ...
alter table table_name add index_name using btree('column_name',...,'column_name'); create unique index index_name on table_name('column_name'); 两者区别: (1)add index_name 支持一次多个索引创建alter table table_name add index_name using btree('column_name',...,'column_name'),add ...
alter table `config` add index idx_config_name(`name`); 1. * 删除索引 alter table `config` drop index idx_config_name; 1. * explain 查看是否使用到了索引 insert into config(name, value, info) values('SMS_ENABLED', '0', '0表示禁用发短信功能, 1表示启用发短信功能'); ...
ALTER TABLE t1 ADD INDEX ((col1 * 40)); Terminology Key part: An index/key consists of one or more key parts. For instance, "CREATE INDEX idx1 ON t1 (col1, col2);" creates one index with two key parts. The key part is a reference to a column in the table, and for STRING/...
the 5.1 mysql_alter_table() is out of the question, then InnoDB Plugin could return a (highly counterintuitive) error for the alter table t drop index b, add index b(b); saying that creating index b would have a duplicate name, even though the user did request to DROP INDEX first.[...
MySQL9.3.0 Source Code Documentation PT_alter_table_add_partition_num Class Referencefinal Parse tree nodes»Nodes representing SQL statements»ALTER TABLE statement Node for theALTER TABLE ADD PARTITION PARTITIONS (<n>@)statement.More...
} else if (index->table->has_instant_cols()) { // 到这里说明record 上面 没有row_version DD 和 instant add 标记, 但是这个index 上面有instant add 标记 // 说明这个record 是instant add 之前就插入的 rec_insert_state = INSERTED_BEFORE_INSTANT_ADD_OLD_IMPLEMENTATION; ...
I am having trouble while adding index on mysql table with ndbcluster storage engine below is the error . [mysqlcluster ver. 7.4 GA] mysql> alter table `sks_staff_office` add index `pid_index` (pid); ERROR 1296