Oracle does not index table rows in which all key columns are null except in the case of bitmap indexes. Therefore, if you want an index on all rows of a table, then you must either specifyNOTNULLconstraints for the index key columns or create a bitmap index. Restrictions on Bitmap I...
Both the unique and non-unique indexes are the B-Tree index structure versions. By default, the B-Tree index is non-unique. To create unique index in Oracle, you need to use the UNIQUE keyword in the CREATE INDEX statement. And now, let’s proceed to the process of creating different ...
在OceanBase 数据库 Oracle 模式下,如果删除表中的任一索引列,则所创建的索引失效。 语法 CREATE[UNIQUE]INDEXindex_name ONtable_name(index_col_name,...)[index_type][index_options]index_type:USINGBTREEindex_options:index_option[index_option...]index_option:GLOBAL|LOCAL|COMMENT'str...
Include the NESTED_TABLE_ID pseudocolumn of the storage table to create a UNIQUE index, which effectively ensures that the rows of a nested table value are distinct. See Also: "Indexes on Nested Tables: Example" You can perform DDL operations (such as ALTER TABLE, DROP TABLE, CREATE ...
使用*_indexes视图的constraint_index列。使用上面的DDL：
CREATE [unique] INDEX [user.]index ON [user.]table (column [ASC | DESC] [,column [ASC | DESC] ] ... ) [CLUSTER [scheam.]cluster] [INITRANS n] [MAXTRANS n] [PCTFREE n] [STORAGE storage] [TABLESPACE tablespace] [NO SORT] ...
T_ID NONUNIQUE 1 56 25,420 1 1 22,731 Index Column Col Column Name Name Pos Details --- --- --- --- T_ID OBJECT_ID 1 NUMBER(22) NOT NULL 注意到表,object_id列和索引都有统计信息了 再来看10.2.0.4的情况 SQL> create table t as select...
B、 It would be created and would use an automatically created unique index. C、 It would be created and would use an automatically created nonunique index. D、 It would be created and remains in a disabled state...
| 1 | INDEX BUILD NON UNIQUE| IND_T23 | | | | | | 2 | SORT CREATE INDEX | | 1000K| 9765K| | | | 3 | TABLE ACCESS FULL | MACLEAN | 1000K| 9765K| 760 (2)| 00:00:10 | --- Note --- -estimated index size: 24M bytes14 rows selected. SQL> create index ind_t23 on ...
Oracle Database - Standard Edition - Version 11.2.0.1 and later: ORA-01452: cannot CREATE UNIQUE INDEX; duplicate keys found or silent corruption / rounding of the f