Comparison of Logical Rowids with Physical Rowids
Logical rowids are similar to the physical rowids in the following ways:
Logical rowids are accessible through the ROWID pseudocolumn.
You can use the ROWID pseudocolumn to select logical rowids from an index-organized table. The
SELECT ROWID statement returns an opaque structure, which internally consists of the table's primary
key and the physical guess (if any) for the row, along with some control information.
You can access a row using predicates of the form WHERE ROWID = value, where value is the opaque
structure returned by SELECT ROWID.
Access through the logical rowid is the fastest way to get to a specific row, although it can
require more than one block access.
A row's logical rowid does not change as long as the primary key value does not change. This is less
stable than the physical rowid, which stays immutable through all updates to the row.
Logical rowids can be stored in a column of the UROWID datatype
One difference between physical and logical rowids is that logical rowids cannot be used to see how
a table is organized.
Note:
An opaque type is one whose internal structure is not known to the database. The database provides
storage for the type. The type designer can provide access to the contents of the type by
implementing functions, typically 3GL routines.
來自 “ ITPUB部落格 ” ,連結:http://blog.itpub.net/10599713/viewspace-983302/,如需轉載,請註明出處,否則將追究法律責任。
相關文章
- Restricted RowidsREST
- BITMAP CONVERSION TO ROWIDS
- bitmap conversion from rowids
- Rowids in Non-Oracle DatabasesOracleDatabase
- BITMAP CONVERSION FROM ROWIDS 適用場景
- oracle sql hint提示_BITMAP CONVERSION FROM ROWIDSOracleSQL
- 執行計劃出現BITMAP CONVERSION TO ROWIDS的解釋!
- oracle10g data guard role transition_physical_logical_switchover_failoverOracleAI
- 沒有備份的情況下如何處理logical & physical corrupt blockBloC
- Oracle 9i Logical Standby與Physical standby歸檔恢復區別Oracle
- 物理Standby資料庫及邏輯Standby資料庫(Physical Standby & Logical Standby)資料庫
- oracle ocp 19c考題8,科目082考試題-logical and physical database structuresOracleDatabaseStruct
- Comparison of Spring and EJB3Spring
- trait in rust, and comparison with interface in javaAIRustJava
- ALL, ANY and SOME Comparison Conditions in SQLSQL
- Samza文件翻譯 : Comparison Introduction
- Comparison of Read Committed and Serializable Isolation (321)MIT
- Physical Storage StructuresStruct
- Physical Database LimitsDatabaseMIT
- Oracle physical standbyOracle
- Oracle Physical Database LimitsOracleDatabaseMIT
- 配置Oracle physical DataGuardOracle
- DataGuard:Physical Standby Switchover
- 建立 Logical Standby DatabaseDatabase
- manage logical standby databaseDatabase
- buffer cache logical structure!Struct
- DataGuard:Logical Standby Switchover
- ISO C++ forbids comparison between pointer and integer [-fpermissive]C++ORB
- Effective STL: Item 21: Always have comparison functions return (轉)Function
- Dataguard Physical Standy Switchover
- physical data guard 的原理
- DataGuard:Physical Standby FailoverAI
- How to Optimize PostgreSQL Logical ReplicationSQL
- 1.1 Logical Structure of Database ClusterStructDatabase
- 75 logical thinking questionsThinking
- DataGuard:Logical Standby FailoverAI
- 監控Logical standby databaseDatabase
- rust-quiz:011-function-pointer-comparison.rsRustUIFunction