ORA普通索引本地索引实例oracle索引类型normal 一:索引分类1、b-tree索引Oracle数据中最常见的索引,就是b-tree索引,create index创建的normal就是b-tree索引。详见 。 2、bitmap位图索引位图索引经常应用于列数据只有几个枚举值的情况,位图索引适合只有几个固定值的列,如性别、婚姻状况、行政区等等,而身份证号这种类...
ALTERINDEX索引名 REBUILD ONLINE vsALTERINDEX索引名 REBUILD; alter index rebuild online实质上是扫描表而不是扫描现有的索引块来实现索引的重建. alter index rebuild 只扫描现有的索引块来实现索引的重建。 rebuild index online在执行期间不会阻塞DML操作,但在开始和结束阶段,需要请求模式为4的TM锁。因此,如果在r...
INDEX_TYPEString索引的类型(NORMAL、BITMAP、FUNCTION-BASED NORMAL、FUNCTION-BASED BITMAP 或 DOMAIN)。 TABLE_OWNERString索引对象的所有者。 TABLE_NAME字符串索引对象的名称。 TABLE_TYPE字符串索引对象的类型(例如 TABLE、CLUSTER)。 UNIQUENESSString索引是 UNIQUE 还是 NONUNIQUE。
Enhancements for Bitmap IndexesSeveral changes enhance query performance when bitmap indexes are used. One of these changes lifts a restriction whereby the use of the ALTER TABLE statement could invalidate a bitmap index. A new feature introduces two new ALTER TABLE statement options: ...
Create BITMAP index indexname on tablename(columnname[columnname…]) (5)函数索引。 Create index indexname on tablename(functionname(columnname)) 注意:创建索引后分析要索引才能起作用。 五种索引的使用场所: (1)BTree索引。 常规索引,多用于oltp系统,快速定位行,应建立于高cardinality列(即列的唯一值除...
create index enable_for_is_null_i on tab ( indexed_column, 1 );Another benefit of bitmaps is it's easy to compress all those ones and zeros. So a bitmap index is typically smaller than the same B-tree index.For example, using a table of Olympic medal winners. Creating indexes on ed...
non-unique index generally Inlist iterator and union all. Nested loop joins Single table, Multi-column index (access/filter, and skip scan) Index-only query (range scan, full scan, fast full scan, index joins) Bitmap access (with multiple bitmaps per key value) Bitmap and / or / minu...
8-24 Using the Index Advisor to recommend indexes... 8-24 Prepare for executing the Index Advisor ... 8-25 Capture the data used for generating index recommendations ... 8-26 Retrieve index recommendations and data
SQL> create bitmap index bowie_kid_fk_i on bowie_kid(dad_id); Index created. SQL> create index bowie_kid_fk2_i on bowie_kid(dad_id) invisible; Index created. Oracle Database 12c allows us to now create multiple indexes on the same column list, providing only one index is visible...
To identify the best possible execution path for SQL statements, the cost-based optimizer (CBO) (introduced in Oracle 7) augments bitmap indexes, function-based indexes, hash joins, and index-organized tables with statistics to select the best access plan based on the cost of various alternative...