unique index:唯一索引;唯一性索引;唯一指数 non-unique index前面加了一个前缀,表示非……,所以整个词组为非唯一索引;可重复索引,非唯一指数 索引是我们经常使用的一种数据库搜索优化手段。适当的业务操作场景使用适当的索引方案可以显著的提升系统整体性能和用户体验。在Oracle中,索引有包括很多类型。不同类型的索引适...
这里,我们看到了Unique Index的一个特性,就是等号操作时执行计划的差异。对Unique Index而言,进行相等查询的结果只有一行值或者没有,所以没必要进行传统的Index Range Scan操作。此处,执行计划中使用的是Index Unique Scan操作,直接精确定位到指定的记录项目,返回rowid记录。 而一般索引在进行等号检索的时候,通常使用的就...
www.oracle.com.cn|基于13个网页 2. 唯一索引 查询结果可以看出,索引zzq_2_index 是BITMAP 索引,位于表zzq_2,位于ZZQ_INDEX表空间 是非唯一索引(NONUNIQUE… chenxy.blog.51cto.com|基于6个网页 3. 非惟一 Also, the first sentence "B*树索引中不存在非惟一(nonunique)条目" sounds confusing. We may ...
Oracle Database - Enterprise Edition - Version 12.1.0.2 and later: ORA-1 or Wrong Results for Parallel INSERT in List/Hash Partitioned Table with Non-Unique Index
SQL Server: how to change a non-unique, non-clustered index to a unique, non-clustered index? Related 13 Modify unique constraint in Oracle 45 Oracle unique constraint and unique index 8 Oracle database, converting unique index to non-unique one 2 Modify table index from unique to non...
Sometimes I get a unique key violation error for an index that isn't unique. I have an Oracle 10g database. There are two indexes on different tables for which is happens. Their details are: CREATED 14-JAN-14 20.14.11 LAST_DDL_TIME 14-JAN-14 20.14.11 ...
Answer:Indexes can be unique or non-unique. Unique indexes guarantee that no two rows of a table have duplicate values in the key column (or columns). Non-unique indexes do not impose this restriction on the column values.Oracle recommends that unique indexes be created explicitly, using ...
Answer:Indexes can be unique or non-unique. Unique indexes guarantee that no two rows of a table have duplicate values in the key column (or columns). Non-unique indexes do not impose this restriction on the column values.Oracle recommends that unique indexes be created explicitly, using ...
Answer:Indexes can be unique or non-unique. Unique indexes guarantee that no two rows of a table have duplicate values in the key column (or columns). Non-unique indexes do not impose this restriction on the column values.Oracle recommends that unique indexes be created explicitly, using ...
Index _ldap._tcp Name does not exist _msdcs could not be resolved , DNS error _msdcs for domain.com in dns mgmt points to old, nonexistent server plus NO OTHER FOLDERS : The security descriptor propagation task could not calculate a new security descriptor for the following object. .bat ...