Introduction to Oracle CREATE INDEX statement# To create a new index for a table, you use theCREATE INDEXstatement. Here’s the syntax of theCREATE INDEXstatement: CREATEINDEXindex_nameONtable_name(column1[,col
ALTER INDEX emp_ix REBUILD REVERSE; Oracle8i 的新功能可以对索引的无用空间进行合并,它由下面命令完成: ALTER INDEX . . . COALESCE; 例如: ALTER INDEX ename_idx COALESCE; §3.5.3 删除索引 当不需要时可以将索引删除以释放出硬盘空间。命令如下: DROP INDEX [schema.]indexname 例如: sql> drop index...
);-- create unique indexCREATEUNIQUEINDEXcollege_indexONColleges(college_code); Run Code Here, the SQL command creates a unique index namedcollege_indexon theCollegestable using thecollege_codecolumn. Note:Although the index is created for only unique values, the original data in the table remains...
Oracle Database Concepts for a discussion of indexes Oracle Database Reference for more information about the limits related to index size ALTER INDEX and DROP INDEX Prerequisites To create an index in your own schema, one of the following conditions must be true: The table or cluster to...
But first, let’s delve into the different types of indexes available in Oracle Database.How to Choose the Index TypeOracle Database offers many different types of index to improve your SQL. One of the key decisions you need to make is whether to go with a bitmap or B-tree index....
(XMLIndex_parameters_clauseについては、『Oracle XML DB開発者ガイド』を参照してください。) local_XMLIndex_clause::= 図「local_xmlindex_clause.gif」の説明 global_partitioned_index::= 図「global_partitioned_index.gif」の説明 (index_partitioning_clause::=、individual_hash_partitions::=、hash_...
SQL 语法 普通租户(Oracle 模式) SQL 语句 DDL CREATE INDEX 更新时间:2023-11-10 11:56:11 编辑 描述 该语句用来创建索引。索引是创建在表上的,对数据库表中一列或多列的值进行排序的一种结构。其作用主要在于提高查询的速度,降低数据库系统的性能开销。
SQL 型 V4.2.0 参考指南 SQL 参考 SQL 语法 普通租户(Oracle 模式) SQL 语句 DDL CREATE INDEX 更新时间:2023-11-10 11:51:07 描述 该语句用来创建索引。索引是创建在表上的,对数据库表中一列或多列的值进行排序的一种结构。其作用主要在于提高查询的速度,降低数据库系统的性能开销。
2、创建索引时并行度可能会等于parallel*2,这是因为oracle产生了两组query slave set,一组用来扫描表,一组用来创建索引; 3、如果数据泵带有sqlfile参数,得到的sql文本中并行度会显示为1,但是在实际导入时是可以并行创建的; 4、导出时未并行导出,导入时只要指定parallel参数同样可以并行创建索引; ...
One more parameter used in the CREATE INDEX statement is COMPUTE STATISTICS. It is an optional parameter telling Oracle to collect the statistics during index creation. Further, this stats data would serve when choosing the “plan of execution” of SQL statements. However, since Oracle 10, the ...