資料整理——Oracle基本概念、術語（Glossary from Oracle Concepts）——第十二部分
阿新 • • 發佈：2018-12-08
“Oracle資料庫的物理檔案是儲存在磁碟上的資料檔案、控制檔案和日誌檔案的總稱。資料檔案和日誌檔案是資料庫中最重要的檔案。資料庫由若干個表空間組成，表空間由表組成，表由段組成，段由區間組成，區間由資料塊組成。那麼，資料在資料檔案中是如何組織的呢？要了解這些內容我們首先必須理解什麼是表空間（tablespace）、段（segment）、區（extent）、塊（block），這些都是oracle資料庫在資料檔案中組織資料的基本單元。”
| 概念 | 中文 | 描述 |
| query transformer | 查詢轉換元件 | An optimizer component that decides whether it can rewrite the original SQL statement into a semantically equivalent SQL statement with a lower cost. |
| R | R語言 | A language and environment for statistical computing and graphics. |
| range partitioning | 範圍分割槽 | A type of partitioning in which the database maps rows to partitions based on ranges of values of the partitioning key. Range partitioning is the most common type of partitioning and is often used with dates. |
| read committed isolation level | 讀已提交隔離級別 | An isolation level that guarantees that a query executed by a transaction sees only data committed before the query—not the transaction—began. |
| read consistency | 讀一致性 | A consistent view of data seen by a user. For example, in statement-level read consistency the set of data seen by a SQL statement remains constant throughout statement execution. See also data concurrency; data consistency. |
| read-only database | 只讀資料庫 | A database that is available for queries only and cannot be modified. |
| read-only isolation level | 只讀隔離級別 | An isolation level that is similar to the serializable isolation level, with one exception: read-only transactions do not permit data to be modified in the transaction unless the user is SYS. |
| real-time redo transport | 實時重做傳輸 | The continuous transfer of redo changes from the SGA of a protected database to a Recovery Appliance. Real-time redo transport enables RMAN to provide a recovery point objective near 0. Typically, RMAN can recover to within a second of the time when the failure occurred. Protected databases write redo entries directly from the SGA to the Recovery Appliance as they are generated. |
| recoverable error | 可恢復錯誤 | A class of errors that arise because of an external system failure, independently of the application session logic that is executing. Recoverable errors occur following planned and unplanned outages of networks, nodes, storage, and databases. An example of a nonrecoverable error is submission of invalid data values. |
| recoverer process (RECO) | RECO（恢復程序） | In a distributed database, the background process that automatically resolves failures in distributed transactions. |
| Recovery Appliance | 恢復機 | Shortened name for Zero Data Loss Recovery Appliance. Recovery Appliance is an Oracle Engineered System specifically designed to protect Oracle databases. Integrated with RMAN, it enables a centralized, incremental-forever backup strategy for hundreds to thousands of databases across the enterprise, using cloud-scale, fully fault-tolerant hardware and storage. |
| Recovery Appliance Backup Module | 恢復機備份模組 | An Oracle-supplied SBT library that RMAN uses to send backups of protected databases over the network to the Recovery Appliance. The library must be installed in each Oracle home used by a protected database. The module functions as an SBT media management library that RMAN references when allocating or configuring a channel for backup to the Recovery Appliance. RMAN performs all backups to the Recovery Appliance, and all restores of complete backup sets, using this module. |
| Recovery Appliance metadata database | 恢復機元資料資料庫 | The Oracle database that runs inside of the Recovery Appliance. This database stores configuration data such as user definitions, protection policy definitions, and client database definitions. The metadata database also stores backup metadata, including the contents of the delta store. |
| Recovery Appliance storage location | 恢復機儲存位置 | A set of Oracle ASM disk groups within Recovery Appliance that stores backups. A storage location can be shared among multiple protected databases. Every Recovery Appliance contains the default Recovery Appliance storage location named DELTA. |
| recovery catalog | 恢復目錄 | A centralized backup repository located in an Oracle database. The recovery catalog contains metadata about RMAN backups. |
| recovery window goal | 恢復視窗目標 | The time interval within which a protected database must be recoverable to satisfy business requirements. For each protected database in a protection policy, the Recovery Appliance attempts to ensure that the oldest backup on disk is able to support a point-in-time recovery to any time within the specified interval (for example, the past 7 days), counting backward from the current time. |
| recursive SQL | 遞迴SQL | SQL that the database executes in the background to obtain space for database objects. You can think of recursive SQL as "side effect" SQL. |
| redo log | 重做日誌 | A set of files that protect altered database data in memory that has not been written to the data files. The redo log can consist of two parts: the online redo log and the archived redo log. |
| redo log buffer | 重做日誌快取 | Memory structure in the SGA that stores redo entries—a log of changes made to the database. The database writes the redo entries stored in the redo log buffers to an online redo log file, which the database uses when instance recovery is necessary. |
| redo record | 重做記錄 | A record in the online redo log that holds a group of change vectors, each of which describes a change made to a data block. Each redo log file consists of redo records. |
| redo thread | 重做執行緒 | The redo generated by a database instance. |
| referenced key | 引用鍵 | In a foreign key relationship, the primary or unique key to which the foreign key refers. For example, in the common schema, the employees.department_id column is a foreign key, and the departments.department_id column is the referenced key. |
| referenced object | 引用物件 | In a schema object dependency, the object that is referenced by another object's definition. For example, if the definition of object A references object B, then B is a referenced object for A. |
| referential integrity | 引用完整性 | A rule defined on a key in one table that guarantees that the values in that key match the values in a key in a related table (the referenced value). |
| relation | 關係 | A set of tuples. |
| relational database | 關係資料庫 | A database that conforms to the relational model, storing data in a set of simple relations. |
| RDBMS (relational database management system) | 關係型資料庫管理系統 | A management system that moves data into a relational database, stores the data, and retrieves it so that applications can manipulate it. |
| replay context | 重播上下文 | In Application Continuity, opaque information that the database returns to the client driver during normal application run time. |
| replication | 複製 | The process of sharing database objects and data at multiple databases. |
| reserved pool | 保留池 | A memory area in the shared pool that Oracle Database can use to allocate large contiguous chunks of memory. |
| result set | 結果集 | The set of data retrieved from execution of a SELECT statement. |
| reverse key index | 反向鍵索引 | A type of B-tree index that physically reverses the bytes of each index key while keeping the column order. For example, if the index key is 20, and if the two bytes stored for this key in hexadecimal are C1,15 in a standard B-tree index, then a reverse key index stores the bytes as 15,C1. |
| right outer join | 右外連線 | The result of a right outer join for table A and B contains all records of the right table B, even if the join condition does not match a record in the left table A. For example, if you perform a right outer join of employees (left) to departments (right), and if some departments contain no employees, then the query returns rows from departments with no matches in employees. |
| RMAN (Recovery Manager) | RMAN (Recovery Manager) | An Oracle Database utility that backs up, restores, and recovers Oracle databases. |
| role | 角色 | A set of privileges that can be granted to database users or to other roles. |
| CDB root | CDB根 | In a multitenant container database (CDB), a collection of schemas, schema objects, and nonschema objects to which all PDBs belong. Every CDB has exactly one root container, which stores the system metadata required to manage PDBs. All PDBs belong to the CDB root. |
| row | 行 | A set of column information corresponding to a single record in a table. The database stores rows in data blocks. |
| row chaining | 行鏈 | A situation in which Oracle Database must store a row in a series or chain of blocks because it is too large to fit into a single block. |
| row lock | 行級鎖 | A lock on a single row of table. A transaction acquires a row lock for each row modified by an INSERT, UPDATE, DELETE, MERGE, or SELECT ... FOR UPDATE statement. |