CREATEORREPLACEFUNCTIONwhale.to_char(timestampwithouttimezone,text)RETURNStextLANGUAGEinternal immutable STRICTNOTFENCED SHIPPABLEAS$function$timestamp_to_char$function$; 然后用常规的方式去创建函数索引,就会自动使用到whale下的这个函数了。当然,使用不当造成本文中oracle出现的那个异常数据,只能由开发人员自己负责...
6.使用in 尽管In写法要比exists简单一些,exists一般来说性能要比In要高的多 用In还是用Exists的时机 当in的集合比较小的时候,或者用Exists无法用到选择性高的索引的时候,用In要好,否则就要用Exists 例:select count(*) from person_info where xb in (select xb_id from dic_sex); Select count(*) from ...
In this tutorial, you will learn how to use the Oracle function-based index to speed up queries that consist of functions.
first argument– a list value to search second argument– value for which to search third argument– (optional) starting index This function returns either the ordinal position of a list element that matches a given value or -1 (the given value is not in the list). Example 1 The following...
function-based indexes, 10-28, 20-7 local, 20-10 managing, 20-1 non-existent referenced objects and, 20-8 on non-existence of other objects, 20-9 Oracle Forms triggers and, 20-13 privileges and, 20-6 remote objects and, 20-10 shared pool and, 20-10 deployment template...
Oracle-index索引解读 Oracle-分区表解读 Oracle-锁解读 Oracle-等待事件解读 Oracle-procedure/cursor解读 索引是数据库对象之一,用于加快数据的检索 索引是建立在表上的可选对象;索引的关键在于通过一组排序后的索引键来取代默认的全表扫描检索方式,索引直接指向包含所查询值的行的位置,减少磁盘I/O,,从而提高检索效率...
Oracle-index索引解读 Oracle-分区表解读 Oracle-锁解读 Oracle-等待事件解读 Oracle-procedure/cursor解读 索引是数据库对象之一,用于加快数据的检索 索引是建立在表上的可选对象;索引的关键在于通过一组排序后的索引键来取代默认的全表扫描检索方式,索引直接指向包含所查询值的行的位置,减少磁盘I/O,,从而提高检索效率...
MySQL从8.0.13开始支持functional index。Functional index类似于ORACLE的Function-Based Indexes。该索引可以根据将索引定义的表达式的值按照索引顺序存到索引里,进而减少表达式的计算,加速查询。 下面我们看一下如何创建一个functional index: CREATE TABLE t1 (col1 INT, col2 INT, INDEX func_index ((ABS(col1))...
This function returns TRUE if all indexes specified were cleaned up and FALSE if one or more indexes could not be cleaned up. Syntax DBMS_REPAIR.ONLINE_INDEX_CLEAN ( object_id IN BINARY_INTEGER DEFAULT ALL_INDEX_ID, wait_for_lock IN BINARY_INTEGER DEFAULT LOCK_WAIT) ...
type ALTER_FUNCTION:"LC"."SXXXT" created with compilationwarnings ORA-39082: Object type VIEW"LC"."WH_XXXXXXXXXXTORY" created with compilation warnings ORA-39082: Objecttype TRIGGER:"LC"."GXXXXXXXXXESS_SEQ" created with compilation warnings 编译告警一般这些对象在源库就已经是INVALID状态了...