DBMS | PJNF (Project-Join Normal Form): In this tutorial, we will learn about the PJNF (Project-Join Normal Form), Properties of 5NF with the help of examples.
对于自定义查询(ad hoc query)或相似的应用,使用位图索引(bitmap index)能够显著地提高查询性能。查询的 WHERE 子句中的 AND 和 OR 条件直接对位图(bitmap)进行布尔运算(Boolean operation)得到一个位图结果集(resulting bitmap),而无需将所有的位图转换为 ROWID。如果布尔操作后的结果集较小,那么查询就能够迅速得...
(data_object_id); Indexcreated SQL>execdbms_stats.gather_table_stats(user,'T',cascade= true); PL/SQLproceduresuccessfullycompleted 2,volumecomparison Inpreparation,wewillsetthevalueforthesameindexcolumn, trytoavoidbecauseofthedifferenceofexternalcauses.Below wecheckinthedatadictionaryinformationcapacity. ...
(identified by operation id): --- 2 - Access (Object _ id = 1000) 统计信息 --- 528 recursive calls 0 dB Block gets Consistent Gets 87 11 physical Reads Redo size 0 1200 bytes sent via SQL * net to Client 376字节通过网络从客户端收到的 2 SQL*Net切换到/从客户端 4类(记忆) 0类(...
唯一性索引（UniqueIndex）与普通索引（NormalIndex）差异（上） 个人分类：oracle工作机制 索引是我们经常使用的一种数据库搜索优化手段。适当的业务操作场景使用适当的索引方案可以显著的提升系统整体性能和用户体验。在Oracle中，索引有包括很多类型。不同类型的索引适应不同的系统环境和访问场景。其中，唯一性索引Uniqu...
BCNF in DBMS: Boyce-Codd Normal Form with DBMS Overview, DBMS vs Files System, DBMS Architecture, Three schema Architecture, DBMS Language, DBMS Keys, DBMS Generalization, DBMS Specialization, Relational Model concept, SQL Introduction, Advantage of SQL,
For a table to be in the Second Normal form, it should be in the First Normal form and it should not have Partial Dependency. Partial Dependency exists, when for a composite primary key, any attribute in the table depends only on a part of the primary key and not on the complete prima...
First Normal form is the first step of normalization. In this tutorial we will have an example to explain how you can update you table to follow the First Normal Form or 1NF. This is the beginning of Database Normalization process.
The ORA-00000 normal, successful completion in Oracle means there is no error in SQL Queries or whatever transactions performed are successful. You can simply ignore this message. As per Oracle error message guide, Cause: An operation has completed normally, having met no exceptions. ...
SQL> exec dbms_stats.gather_table_stats(user,'T',cascade => true); PL/SQL procedure successfully completed SQL> col object_name for a20; SQL> select object_name, object_id from dba_objects where object_name in ('IDX_T_NORMALID','IDX_T_UNIQUEID'); ...