Function-based index 可以很巧妙地帮助我们实现“不一般”的unique index, 但是如果没有注意function-based index对于该index对应的function的要求,很有可能会触发ORA-01802这个错误。 本文尝试去阐述这个错误是如何触发的,以及如果去解决。 OK, let’s get down to business. 记得Tom大叔的力作《Oracle编程艺术》中提...
In this tutorial, you will learn how to use the Oracle function-based index to speed up queries that consist of functions.
函数索引(Function-based indexes)只有在where条件使用了与索引中相同的基于相同列的函数时才起作用。duzz$scott@orcl>set autotrace on duzz$scott@orcl>create table t1 as select * from dept; Table created. Elapsed: 00:00:00.01 duzz$scott@orcl>create index loc_idx on t1(upper(loc)); Index crea...
Oracle Database - Enterprise Edition - Version 12.2.0.1 and later: After Partitioning Table Using 'ALTER TABLE MODIFY PARTITION' Statement, FUNCTION-BASED Index Gets
Because 'DECODE(status, 'C', null, status)' has been set in the Function-Based Index 'T1_STATUS_FN', you, certainly, create the virtual column 'virtual_status' with 'DECODE(status, 'C', null, status)' and Oracle will show this error: 'ORA-54015: Duplicate column expression was speci...
Oracle PL/SQL之函数索引(Function-based indexes)使用示例,函数索引(Function-basedindexes)只有在where条件使用了与索引中相同的基于相同列的函数时才起作用。duzz$scott@orcl>setautotraceonduzz$scott@orcl>createtablet1asselect*fromdept;Tablecreated.Elapsed:0
the optimizer can elect to use the previous result. The function result should not depend on the state of session variables or schema objects. Otherwise, results might vary across calls. Only DETERMINISTIC functions can be called from a function-based index or a materialized view that has query...
链接:https://www.eygle.com/archives/2006/01/create_function_based_index.html 留言版上的第2330号问题是: 在oralce中给自建函数创建索引,结果不成功。 source:Create Index IDX_T_SP_TWOTYPESTAT_0_f On T_SP_TWOTYPESTAT_0(f_dateadd(yearmonth,12,2)); ...
A nonunique index can be used to enforce a primary key or unique constraint. In Oracle8i indexes can be rebuilt without locking the table. The DROP COLUMN option of the ALTER TABLE command is restartable. The MOVE option of the ALTER TABLE command retains the constraints of the table. Data...
1. 解释什么是Oracle中的Function-Based Normal索引 Function-Based Normal索引(基于函数的普通索引)是Oracle数据库中一种特殊的索引类型,它允许用户根据列上的函数或表达式的结果来创建索引。这种索引类型不同于传统的基于单列或多列的索引,因为它不直接对表中的列值进行索引,而是对列值经过特定函数处理后的结果进行...