这个Enabled只能对FBI索引使用。 C:ALTER INDEX UNUSABLE; 注意:如果一个查询中使用到了这个索引,但是这个FBI索引的状态是DISABLED,但是优化器选择了使用这个索引,那么将会返回一个Oracle错误。 例子: ORA error: ERROR at line 1: ORA-30554: function-based index MYUSER.FBI is disabled. 而且,一旦这个FBI索引的...
expression specified in the index, and the hidden generated column is then indexed. This function adds a hidden generated column to the Create_list, and updates the key specification to point to this new column. The generated column is given a name that is a hash of the key name and the ...
Function-Based Index on numeric Column 3369 Nicola Pascelupo March 25, 2011 07:28AM Re: Function-Based Index on numeric Column; num LIKE '123%' 1140 Rick James March 26, 2011 10:34AM Sorry, you can't reply to this topic. It has been closed. ...
, now the indexis used. rewritingthe querywas the typicalsuggestion. Quite a simple solution but not all the times was possible to change the application code for manyvalid reasons. So, what to do then? What is a Function-based Index? A function-based index is an indexing ...
Oracle8i的很重要的一个新特性就是增加了function-based index这种索引类型(后面简称为FBI)。有了这个特性后,Oracle DBA就可以在索引中使用函数或者表达式了。这些函数可以使Oracle自己的函数,也可以使用户自己的PL/SQL函数等。DBA在SQL语句调优的过程中遇到的一个很常见的问题就是,如何优化那些在WHERE子句中使用了函数...
7)基于函数的索引Function-based 2.索引结构 1)B-tree: 适合与大量的增、删、改(OLTP); 不能用包含OR操作符的查询; 适合高基数的列(唯一值多) 2)典型的树状结构; 每个结点都是数据块; 大多都是物理上一层、两层或三层不定,逻辑上三层; 叶子块数据是排序的,从左向右递增; ...
InnoDB存储引擎中的主键索引(primary key)又叫做聚集索引(clustered index)。因为InnoDB的数据文件本身要按主键聚集,所以InnoDB要求表必须有主键(MyISAM可以没有),如果没有显式指定,则MySQL系统会自动选择一个可以唯一标识数据记录的列作为主键,如果不存在这种列,则MySQL自动为InnoDB表生成一个隐含字段作为主键,这个字段长...
log-bin=/path/logs/mysql-binlog全局静态参数。打开二进制日志功能,在复制(replication)配置中,作为MASTER主服务器必须打开此项。如果需要从最后的备份中做基于时间点的恢复,也同样需要二进制日志。默认在datadir下。这样设置后相当于,制定了log_bin_basename和log_bin_index的配置。
A multiple-column index can be considered a sorted array, the rows of which contain values that are created by concatenating the values of the indexed columns. 联合索引是多列按照次序一列一列比较大小,拿idx_book_id_hero_name这个联合索引来说,先比较book_id,book_id小的排在左边,book_id大的排在...
I understand that there are no function based indexes but there are alternatives like generated columns. But, I wanted to check if there is a possibility to add an index on (col1 + offset) without adding a new column ?? Thanks in advance ...