PostgreSQL 正體中文使用手冊
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  • 簡介
  • 前言
    • 1. 什麼是 PostgreSQL?
    • 2. PostgreSQL 沿革
    • 3. 慣例
    • 4. 其他參考資訊
    • 5. 問題回報指南
  • I. 新手教學
    • 1. 入門指南
      • 1.1. 安裝
      • 1.2. 基礎架構
      • 1.3. 建立一個資料庫
      • 1.4. 存取一個資料庫
    • 2. SQL 查詢語言
      • 2.1. 簡介
      • 2.2. 概念
      • 2.3. 創建一個新的資料表
      • 2.4. 資料列是資料表的組成單位
      • 2.5. 資料表的查詢
      • 2.6. 交叉查詢
      • 2.7. 彙總查詢
      • 2.8. 更新資料
      • 2.9. 刪除資料
    • 3. 先進功能
      • 3.1. 簡介
      • 3.2. 檢視表(View)
      • 3.3. 外部索引鍵
      • 3.4. 交易安全
      • 3.5. 窗函數
      • 3.6. 繼承
      • 3.7. 結論
  • II. SQL 查詢語言
    • 4. SQL 語法
      • 4.1. 語法結構
      • 4.2. 參數表示式
      • 4.3. 函數呼叫
    • 5. 定義資料結構
      • 5.1. 認識資料表
      • 5.2. 預設值
      • 5.3. Generated Columns
      • 5.4. 限制條件
      • 5.5. 系統欄位
      • 5.6. 表格變更
      • 5.7. 權限
      • 5.8. 資料列安全原則
      • 5.9. Schemas
      • 5.10. 繼承
      • 5.11. 分割資料表
      • 5.12. 外部資料
      • 5.13. 其他資料庫物件
      • 5.14. 相依性追蹤
    • 6. 資料處理
      • 6.1. 新增資料
      • 6.2. 更新資料
      • 6.3. 刪除資料
      • 6.4. 修改並回傳資料
    • 7. 資料查詢
      • 7.1. 概觀
      • 7.2. 資料表表示式
      • 7.3. 取得資料列表
      • 7.4. 合併查詢結果
      • 7.5. 資料排序
      • 7.6. LIMIT 和 OFFSET
      • 7.7. VALUES 列舉資料
      • 7.8. WITH Querys(Common Table Expressions)
    • 8. 資料型別
      • 8.1. 數字型別
      • 8.2. 貨幣型別
      • 8.3. 字串型別
      • 8.4. 位元組型別(bytea)
      • 8.5. 日期時間型別
      • 8.6. 布林型別
      • 8.7. 列舉型別
      • 8.8. 地理資訊型別
      • 8.9. 網路資訊型別
      • 8.10. 位元字串型別
      • 8.11. 全文檢索型別
      • 8.12. UUID 型別
      • 8.13. XML 型別
      • 8.14. JSON 型別
      • 8.15. 陣列
      • 8.16. 複合型別
      • 8.17. 範圍型別
      • 8.18. Domain Types
      • 8.19. 物件指標型別
      • 8.20. pg_lsn 型別
      • 8.21. 概念型別
    • 9. 函式及運算子
      • 9.1. 邏輯運算子
      • 9.2. 比較函式及運算子
      • 9.3. 數學函式及運算子
      • 9.4. 字串函式及運算子
      • 9.5. 位元字串函式及運算子
      • 9.6. 二元字串函式及運算子
      • 9.7. 特徵比對
      • 9.8. 型別轉換函式
      • 9.9 日期時間函式及運算子
      • 9.10. 列舉型別函式
      • 9.11. 地理資訊函式及運算子
      • 9.12. 網路位址函式及運算子
      • 9.13. 文字檢索函式及運算子
      • 9.14. UUID Functions
      • 9.15. XML 函式
      • 9.16. JSON 函式及運算子
      • 9.17. 序列函式
      • 9.18. 條件表示式
      • 9.19. 陣列函式及運算子
      • 9.20. 範圍函式及運算子
      • 9.21. 彙總函數
      • 9.22. Window 函式
      • 9.23. 子查詢
      • 9.24. 資料列與陣列的比較運算
      • 9.25. 集合回傳函式
      • 9.26. 系統資訊函數
      • 9.27. 系統管理函式
      • 9.28. 觸發函式
      • 9.29. 事件觸發函式
      • 9.30. Statistics Information Functions
    • 10. 型別轉換
      • 10.1. 概觀
      • 10.2. 運算子
      • 10.3. 函式
      • 10.4. 資料儲存轉換規則
      • 10.5. UNION、CASE 等相關結構
      • 10.6. SELECT 輸出規則
    • 11. 索引(Index)
      • 11.1. 簡介
      • 11.2. 索引型別
      • 11.3. 多欄位索引
      • 11.4. 索引與 ORDER BY
      • 11.5. 善用多個索引
      • 11.6. 唯一值索引
      • 11.7. 表示式索引
      • 11.8. 部份索引(partial index)
      • 11.9. Index-Only Scans and Covering Indexes
      • 11.10. 運算子物件及家族
      • 11.11. 索引與排序規則
      • 11.12. 檢查索引運用
    • 12. 全文檢索
      • 12.1. 簡介
      • 12.2. 查詢與索引
      • 12.3. 細部控制
      • 12.4. 延伸功能
      • 12.5. 斷詞
      • 12.6. 字典
      • 12.7. 組態範例
      • 12.8. 測試與除錯
      • 12.9. GIN 及 GiST 索引型別
      • 12.10. psql支援
      • 12.11. 功能限制
    • 13. 一致性管理(MVCC)
      • 13.1. 簡介
      • 13.2. 交易隔離
      • 13.3. 鎖定模式
      • 13.4. 在應用端檢視資料一致性
      • 13.5. 特別注意
      • 13.6. 鎖定與索引
    • 14. 效能技巧
      • 14.1. 善用 EXPLAIN
      • 14.2. 統計資訊
      • 14.3. 使用確切的 JOIN 方式
      • 14.4. 快速建立資料庫內容
      • 14.5. 風險性彈性設定
    • 15. 平行查詢
      • 15.1. 如何運作?
      • 15.2. 啓用時機?
      • 15.3. 平行查詢計畫
      • 15.4. 平行查詢的安全性
  • III. 系統管理
    • 16. Installation from Binaries
    • 17. 用原始碼安裝
      • 16.1. Short Version
      • 16.2. Requirements
      • 16.3. Getting The Source
      • 16.4. 安裝流程
      • 16.5. Post-Installation Setup
      • 16.6. Supported Platforms
      • 16.7. 平台相關的注意事項
    • 18. 用原始碼在 Windows 上安裝
      • 17.1. Building with Visual C++ or the Microsoft Windows SDK
    • 19. 服務配置與維運
      • 18.1. PostgreSQL 使用者帳號
      • 18.2. Creating a Database Cluster
      • 18.3. Starting the Database Server
      • 18.4. 核心資源管理
      • 18.5. Shutting Down the Server
      • 18.6. Upgrading a PostgreSQL Cluster
      • 18.7. Preventing Server Spoofing
      • 18.8. Encryption Options
      • 18.9. Secure TCP/IP Connections with SSL
      • 18.10. Secure TCP/IP Connections with GSSAPI Encryption
      • 18.11. Secure TCP/IP Connections with SSH Tunnels
      • 18.12. 在 Windows 註冊事件日誌
    • 20. 服務組態設定
      • 19.1. Setting Parameters
      • 19.2. File Locations
      • 19.3. 連線與認證
      • 19.4. 資源配置
      • 19.5. Write Ahead Log
      • 19.6. 複寫(Replication)
      • 19.7. 查詢規畫
      • 19.8. 錯誤回報與日誌記錄
      • 19.9. 執行階段統計資訊
      • 19.10. 自動資料庫清理
      • 20.11. 用戶端連線預設參數
      • 19.12. 交易鎖定管理
      • 19.13. 版本與平台的相容性
      • 19.14. Error Handling
      • 19.15. 預先配置的參數
      • 19.16. Customized Options
      • 19.17. Developer Options
      • 19.18. Short Options
    • 21. 使用者認證
      • 20.1. 設定檔:pg_hba.conf
      • 20.2. User Name Maps
      • 20.3. Authentication Methods
      • 20.4. Trust Authentication
      • 20.5. Password Authentication
      • 20.6. GSSAPI Authentication
      • 20.7. SSPI Authentication
      • 20.8. Ident Authentication
      • 20.9. Peer Authentication
      • 20.10. LDAP Authentication
      • 20.11. RADIUS Authentication
      • 20.12. Certificate Authentication
      • 20.13. PAM Authentication
    • 22. 資料庫角色
      • 22.1. Database Roles
      • 22.2. Role Attributes
      • 22.3. Role Membership
      • 22.4. 移除角色
      • 22.5. Default Roles
      • 22.6. Function Security
    • 23. Managing Databases
      • 22.1. Overview
      • 22.2. Creating a Database
      • 22.3. 樣版資料庫
      • 22.4. Database Configuration
      • 22.5. Destroying a Database
      • 22.6. Tablespaces
    • 24. 語系
      • 23.1. 語系支援
      • 23.2. Collation Support
      • 23.3. 字元集支援
    • 25. 例行性資料庫維護工作
      • 25.1. 例行性資料清理
      • 25.2. 定期重建索引
      • 25.3. Log 檔案維護
    • 26. 備份及還原
      • 25.1. SQL Dump
      • 25.2. 檔案系統層級備份
      • 25.3. Continuous Archiving and Point-in-Time Recovery (PITR)
    • 27. High Availability, Load Balancing, and Replication
      • 26.1. 比較不同的解決方案
      • 26.2. 日誌轉送備用伺服器 Log-Shipping Standby Servers
      • 26.3. Failover
      • 26.4. Alternative Method for Log Shipping
      • 26.5. Hot Standby
    • 28. 監控資料庫活動
      • 27.1. Standard Unix Tools
      • 27.2. 統計資訊收集器
      • 27.3. Viewing Locks
      • 27.4. Progress Reporting
      • 27.5. Dynamic Tracing
    • 29. 監控磁碟使用情況
      • 28.1. 瞭解磁碟使用情形
      • 28.2. 磁碟空間不足錯誤
    • 30. 高可靠度及預寫日誌
      • 29.1. 可靠度
      • 29.2. Write-Ahead Logging(WAL)
      • 29.3. Asynchronous Commit
      • 29.4. WAL Configuration
      • 29.5. WAL Internals
    • 31. 邏輯複寫(Logical Replication)
      • 30.1. 發佈(Publication)
      • 30.2. 訂閱(Subscription)
      • 30.3. 衝突處理
      • 30.4. 限制
      • 30.5. 架構
      • 30.6. 監控
      • 30.7. 安全性
      • 30.8. 系統設定
      • 30.9. 快速設定
    • 32. Just-in-Time Compilation(JIT)
      • 31.1. What is JIT compilation?
      • 31.2. When to JIT?
      • 31.3. Configuration
      • 31.4. Extensibility
    • 33. 迴歸測試
      • 32.1. Running the Tests
      • 32.2. Test Evaluation
      • 32.3. Variant Comparison Files
      • 32.4. TAP Tests
      • 32.5. Test Coverage Examination
  • IV. 用戶端介面
    • 33. libpq - C Library
      • 33.1. 資料庫連線控制函數
      • 33.2. 連線狀態函數
      • 33.3. Command Execution Functions
      • 33.4. Asynchronous Command Processing
      • 33.5. Retrieving Query Results Row-By-Row
      • 33.6. Canceling Queries in Progress
      • 33.7. The Fast-Path Interface
      • 33.8. Asynchronous Notification
      • 33.9. Functions Associated with the COPY Command
      • 33.10. Control Functions
      • 33.11. Miscellaneous Functions
      • 33.12. Notice Processing
      • 33.13. Event System
      • 33.14. 環境變數
      • 33.15. 密碼檔
      • 33.16. The Connection Service File
      • 33.17. LDAP Lookup of Connection Parameters
      • 33.18. SSL Support
      • 33.19. Behavior in Threaded Programs
      • 33.20. Building libpq Programs
      • 33.21. Example Programs
    • 34. Large Objects
      • 35.1. Introduction
      • 35.2. Implementation Features
      • 35.3. Client Interfaces
      • 35.4. Server-side Functions
      • 35.5. Example Program
    • 35. ECPG - Embedded SQL in C
      • 35.1. The Concept
      • 35.2. Managing Database Connections
      • 35.3. Running SQL Commands
      • 35.4. Using Host Variables
      • 35.5. Dynamic SQL
      • 35.6. pgtypes Library
      • 35.7. Using Descriptor Areas
      • 35.8. Error Handling
      • 35.9. Preprocessor Directives
      • 35.10. Processing Embedded SQL Programs
      • 35.11. Library Functions
      • 35.12. Large Objects
      • 35.13. C++ Applications
      • 35.14. Embedded SQL Commands
      • 35.15. Informix Compatibility Mode
      • 35.16. Internals
    • 36. The Information Schema
      • 36.1. The Schema
      • 36.2. Data Types
      • 36.3. information_schema_catalog_name
      • 36.4. administrable_role_authorizations
      • 36.5. applicable_roles
      • 36.6. attributes
      • 36.7. character_sets
      • 36.8. check_constraint_routine_usage
      • 36.9. check_constraints
      • 36.10. collations
      • 36.11. collation_character_set_applicability
      • 36.12. column_domain_usage
      • 36.13. column_options
      • 36.14. column_privileges
      • 36.16. column_udt_usage
      • 36.17. columns
      • 36.18. constraint_column_usage
      • 37.18. constraint_table_usage
      • 37.19. data_type_privileges
      • 37.20. domain_constraints
      • 37.21. domain_udt_usage
      • 37.22. domains
      • 37.23. element_types
      • 37.24. enabled_roles
      • 37.25. foreign_data_wrapper_options
      • 37.26. foreign_data_wrappers
      • 37.27. foreign_server_options
      • 37.28. foreign_servers
      • 37.29. foreign_table_options
      • 37.30. foreign_tables
      • 36.32. key_column_usage
      • 36.33. parameters
      • 36.34. referential_constraints
      • 37.34. role_column_grants
      • 37.35. role_routine_grants
      • 36.37. role_table_grants
      • 37.37. role_udt_grants
      • 37.38. role_usage_grants
      • 37.39. routine_privileges
      • 37.40. routines
      • 36.42. schemata
      • 37.42. sequences
      • 37.43. sql_features
      • 37.44. sql_implementation_info
      • 37.45. sql_languages
      • 37.46. sql_packages
      • 37.47. sql_parts
      • 37.48. sql_sizing
      • 37.49. sql_sizing_profiles
      • 36.51. table_constraints
      • 36.49. table_privileges
      • 37.52. tables
      • 37.53. transforms
      • 37.54. triggered_update_columns
      • 37.55. triggers
      • 37.56. udt_privileges
      • 37.57. usage_privileges
      • 37.58. user_defined_types
      • 37.59. user_mapping_options
      • 37.60. user_mappings
      • 37.61. view_column_usage
      • 37.62. view_routine_usage
      • 37.63. view_table_usage
      • 37.64. views
  • V. 資料庫程式設計
    • 38. SQL 延伸功能
      • 38.1. How Extensibility Works
      • 37.2. The PostgreSQL Type System
      • 37.3. 使用者自訂函數
      • 37.4. User-defined Procedures
      • 37.5. Query Language (SQL) Functions
      • 37.6. Function Overloading
      • 37.7. 函數易變性類別
      • 37.8. Procedural Language Functions
      • 37.9. Internal Functions
      • 37.10. C-Language Functions
      • 37.11. Function Optimization Information
      • 37.12. User-defined Aggregates
      • 37.13. User-defined Types
      • 37.14. User-defined Operators
      • 37.15. Operator Optimization Information
      • 38.16. Interfacing Extensions To Indexes
      • 37.17. 封裝相關物件到延伸功能中
      • 37.18. Extension Building Infrastructure
    • 38. Triggers
      • 38.1. Overview of Trigger Behavior
      • 38.2. Visibility of Data Changes
      • 38.3. Writing Trigger Functions in C
      • 38.4. A Complete Trigger Example
    • 39. Event Triggers (事件觸發)
      • 39.1. Overview of Event Trigger Behavior
      • 39.2. Event Trigger Firing Matrix
      • 39.3. Writing Event Trigger Functions in C
      • 39.4. A Complete Event Trigger Example
    • 40. 規則系統
      • 40.1. The Query Tree
      • 40.2. Views and the Rule System
      • 40.3. Materialized Views
      • 40.4. Rules on INSERT, UPDATE, and DELETE
      • 40.5. 規則及權限
      • 40.6. Rules and Command Status
      • 40.7. Rules Versus Triggers
    • 41. Procedural Languages(程序語言)
      • 41.1. Installing Procedural Languages
      • 41.2. Structure of PL/pgSQL
      • 41.5. Basic Statements
      • 41.11. 深入了解 PL/pgSQL
    • 42. PL/pgSQL - SQL Procedural Language
      • 42.1. Overview
      • 42.2. Structure of PL/pgSQL
      • 42.3. Declarations
      • 42.4. Expressions
      • 42.5. 基本語法
      • 42.6. Control Structures
    • 43. PL/Tcl - Tcl Procedural Language
    • 44. PL/Perl — Perl Procedural Language
    • 45. PL/Python - Python Procedural Language
      • 45.1. Python 2 vs. Python 3
      • 45.2. PL/Python Functions
      • 45.3. Data Values
      • 45.4. Sharing Data
      • 45.5. Anonymous Code Blocks
      • 45.6. Trigger Functions
      • 45.7. Database Access
      • 45.8. Explicit Subtransactions
      • 45.9. Transaction Management
      • 45.10. Utility Functions
      • 45.11. Environment Variables
    • 46. Server Programming Interface
    • 47. Background Worker Processes
    • 48. Logical Decoding
      • 48.1. Logical Decoding Examples
      • 48.2. Logical Decoding Concepts
      • 48.3. Streaming Replication Protocol Interface
      • 48.4. Logical Decoding SQL Interface
      • 48.5. System Catalogs Related to Logical Decoding
      • 48.6. Logical Decoding Output Plugins
      • 48.7. Logical Decoding Output Writers
      • 48.8. Synchronous Replication Support for Logical Decoding
    • 49. Replication Progress Tracking
  • VI. 參考資訊
    • I. SQL 指令
      • ALTER DATABASE
      • ALTER DEFAULT PRIVILEGES
      • ALTER EXTENSION
      • ALTER FUNCTION
      • ALTER INDEX
      • ALTER LANGUAGE
      • ALTER MATERIALIZED VIEW
      • ALTER POLICY
      • ALTER PUBLICATION
      • ALTER ROLE
      • ALTER RULE
      • ALTER SCHEMA
      • ALTER SEQUENCE
      • ALTER STATISTICS
      • ALTER SUBSCRIPTION
      • ALTER SYSTEM
      • ALTER TABLE
      • ALTER TABLESPACE
      • ALTER TRIGGER
      • ALTER TYPE
      • ALTER USER
      • ALTER VIEW
      • ANALYZE
      • CLUSTER
      • COMMENT
      • COMMIT PREPARED
      • COPY
      • CREATE ACCESS METHOD
      • CREATE CAST
      • CREATE DATABASE
      • CREATE EVENT TRIGGER
      • CREATE EXTENSION
      • CREATE FOREIGN TABLE
      • CREATE FOREIGN DATA WRAPPER
      • CREATE FUNCTION
      • CREATE INDEX
      • CREATE LANGUAGE
      • CREATE MATERIALIZED VIEW
      • CREATE DOMAIN
      • CREATE POLICY
      • CREATE PROCEDURE
      • CREATE PUBLICATION
      • CREATE ROLE
      • CREATE RULE
      • CREATE SCHEMA
      • CREATE SEQUENCE
      • CREATE SERVER
      • CREATE STATISTICS
      • CREATE SUBSCRIPTION
      • CREATE TABLE
      • CREATE TABLE AS
      • CREATE TABLESPACE
      • CREATE TRANSFORM
      • CREATE TRIGGER
      • CREATE TYPE
      • CREATE USER
      • CREATE USER MAPPING
      • CREATE VIEW
      • DEALLOCATE
      • DELETE
      • DO
      • DROP ACCESS METHOD
      • DROP DATABASE
      • DROP EXTENSION
      • DROP FUNCTION
      • DROP INDEX
      • DROP LANGUAGE
      • DROP MATERIALIZED VIEW
      • DROP OWNED
      • DROP POLICY
      • DROP PUBLICATION
      • DROP ROLE
      • DROP RULE
      • DROP SCHEMA
      • DROP SEQUENCE
      • DROP STATISTICS
      • DROP SUBSCRIPTION
      • DROP TABLE
      • DROP TABLESPACE
      • DROP TRANSFORM
      • DROP TRIGGER
      • DROP TYPE
      • DROP USER
      • DROP VIEW
      • EXECUTE
      • EXPLAIN
      • GRANT
      • IMPORT FOREIGN SCHEMA
      • INSERT
      • LISTEN
      • LOAD
      • NOTIFY
      • PREPARE
      • PREPARE TRANSACTION
      • REASSIGN OWNED
      • REFRESH MATERIALIZED VIEW
      • REINDEX
      • RESET
      • REVOKE
      • ROLLBACK PREPARED
      • SECURITY LABEL
      • SELECT
      • SELECT INTO
      • SET
      • SET CONSTRAINTS
      • SET ROLE
      • SET SESSION AUTHORIZATION
      • SET TRANSACTION
      • SHOW
      • TRUNCATE
      • UNLISTEN
      • UPDATE
      • VACUUM
      • VALUES
    • II. PostgreSQL 用戶端工具
      • createdb
      • createuser
      • dropdb
      • dropuser
      • oid2name
      • pgbench
      • pg_basebackup
      • pg_dump
      • pg_dumpall
      • pg_isready
      • pg_receivewal
      • pg_recvlogical
      • pg_restore
      • pg_verifybackup
      • psql
      • vacuumdb
    • III. PostgreSQL 伺服器應用程式
      • initdb
      • pg_archivecleanup
      • pg_ctl
      • pg_standby
      • pg_test_timing
      • pg_upgrade
      • postgres
  • VII. 資料庫進階
    • 50. PostgreSQL 的內部架構
      • 50.1. 處理查詢語句的流程
      • 50.2. How Connections Are Established
      • 50.3. The Parser Stage
      • 50.4. The PostgreSQL Rule System
      • 50.5. Planner/Optimizer
      • 50.6. Executor
    • 51. 系統目錄
      • 51.3. pg_am
      • 51.7. pg_attribute
      • 51.8. pg_authid
      • 51.9. pg_auth_members
      • 51.10. pg_cast
      • 51.11 pg_class
      • 51.12. pg_collation
      • 51.13. pg_constraint
      • 51.15 pg_database
      • 51.21. pg_event_trigger
      • 51.22. pg_extension
      • 51.26 pg_index
      • 51.29. pg_language
      • 51.32. pg_namespace
      • 51.33. pg_opclass
      • 51.38. pg_policy
      • 51.39. pg_proc
      • 51.44. pg_rewrite
      • 51.49. pg_statistic
      • 51.50. pg_statistic_ext
      • 51.52. pg_subscription
      • 51.53. pg_subscription_rel
      • 51.54. pg_tablespace
      • 51.56. pg_trigger
      • 51.62. pg_type
      • 51.66. pg_available_extensions
      • 51.67. pg_available_extension_versions
      • 51.71. pg_hba_file_rules
      • 51.72. pg_indexes
      • 51.73. pg_locks
      • 51.77. pg_prepared_xacts
      • 51.79. pg_replication_origin_status
      • 51.80. pg_replication_slots
      • 51.82 pg_roles
      • 51.85. pg_settings
      • 51.87. pg_shmem_allocations
      • 51.88. pg_stats
      • 51.90. pg_tables
      • 51.93. pg_user
      • 51.95. pg_views
    • 52. Frontend/Backend Protocol
      • 52.1. Overview
      • 52.2. Message Flow
      • 52.3. SASL Authentication
      • 52.4. Streaming Replication Protocol
      • 52.5. Logical Streaming Replication Protocol
      • 52.6. Message Data Types
      • 52.7. Message Formats
      • 52.8. Error and Notice Message Fields
      • 52.9. Logical Replication Message Formats
      • 52.10. Summary of Changes since Protocol 2.0
    • 53. PostgreSQL 程式撰寫慣例
      • 53.1. Formatting
      • 53.2. Reporting Errors Within the Server
      • 53.3. Error Message Style Guide
      • 53.4. Miscellaneous Coding Conventions
    • 54. Native Language Support
      • 54.1. For the Translator
      • 54.2. For the Programmer
    • 55. 撰寫程序語言的處理程序
    • 56. Writing a Foreign Data Wrapper
      • 56.1. Foreign Data Wrapper Functions
      • 56.2. Foreign Data Wrapper Callback Routines
      • 56.3. Foreign Data Wrapper Helper Functions
      • 56.4. Foreign Data Wrapper Query Planning
      • 56.5. Row Locking in Foreign Data Wrappers
    • 59. Genetic Query Optimizer
      • 59.1. Query Handling as a Complex Optimization Problem
      • 59.2. Genetic Algorithms
      • 59.3. Genetic Query Optimization (GEQO) in PostgreSQL
      • 59.4. Further Reading
    • 60. Table Access Method Interface Definition
    • 61. Index Access Method Interface Definition
    • 62. Generic WAL Records
    • 64. B-Tree Indexes
      • 64.1. Introduction
      • 64.2. Behavior of B-Tree Operator Classes
      • 64.3. B-Tree Support Functions
      • 64.4. Implementation
    • 64. GiST Indexes
      • 64.1. Introduction
      • 64.2. Built-in Operator Classes
      • 64.3. Extensibility
      • 64.4. Implementation
      • 64.5. Examples
    • 65. SP-GiST Indexes
      • 65.1. Introduction
      • 65.2. Built-in Operator Classes
      • 65.3. Extensibility
      • 65.4. Implementation
      • 65.5. Examples
    • 66. GIN 索引
      • 66.1. 簡介
      • 66.2. 內建運算子類
      • 66.3. 延伸介面
      • 66.4. 實作說明
      • 66.5. GIN 小巧技
      • 66.6. 限制
      • 66.7. 範例
    • 67. BRIN Indexes
      • 67.1. Introduction
      • 67.2. Built-in Operator Classes
      • 67.3. Extensibility
    • 68. 資料庫實體儲存格式
      • 68.1. Database File Layout
      • 68.2. TOAST
      • 68.3. Free Space Map
      • 68.4 可視性映射表(Visibility Map)
      • 68.5. The Initialization Fork
      • 68.6. Database Page Layout
    • 69. System Catalog Declarations and Initial Contents
    • 70. 查詢計畫如何使用統計資訊
      • 70.1. Row Estimation Examples
      • 70.2. 多元統計資訊範例
      • 70.3. Planner Statistics and Security
    • 71. Backup Manifest Format
  • VIII. 附錄
    • A. PostgreSQL 錯誤代碼
    • B. 日期時間格式支援
      • B.1. 日期時間解譯流程
      • B.2. 日期時間慣用字
      • B.3. 日期時間設定檔
      • B.4. 日期時間的沿革
    • C. SQL 關鍵字
    • D. SQL 相容性
      • D.1. Supported Features
      • D.2. Unsupported Features
      • D.3. XML Limits and Conformance to SQL/XML
    • E. 版本資訊
      • E.1. Release 14
    • F. 延伸支援模組
      • F.1. adminpack
      • F.2. amcheck
      • F.3. auth_delay
      • F.4. auto_explain
      • F.5. bloom
      • F.6. btree_gin
      • F.10. dblink
        • dblink_connect
        • dblink_connect_u
        • dblink_disconnect
        • dblink
        • dblink_exec
        • dblink_open
        • dblink_fetch
        • dblink_close
        • dblink_get_connections
        • dblink_error_message
        • dblink_send_query
        • dblink_is_busy
        • dblink_get_notify
        • dblink_get_result
        • dblink_cancel_query
        • dblink_get_pkey
        • dblink_build_sql_insert
        • dblink_build_sql_delete
        • dblink_build_sql_update
      • F.13. earthdistance
      • F.14. file_fdw
      • F.16. hstore
      • F.24. pg_buffercache
      • F.29. pg_stat_statements
      • F.30. pgstattuple
      • F.31. pg_trgm
      • F.32. pg_visibility
      • F.33. postgres_fdw
      • F.35. sepgsql
      • F.38. tablefunc
      • F.40. test_decoding
      • F.41. tsm_system_rows
      • F.42. tsm_system_time
      • F.44. uuid-ossp
    • G. Additional Supplied Programs
      • G.1. Client Applications
        • oid2name
        • vacuumlo
      • G.2. Server Applications
        • pg_standby
    • H. 外部專案
      • H.1. 用戶端介面
      • H.2. Administration Tools
      • H.3. Procedural Languages
      • H.4. Extensions
    • I. The Source Code Repository
      • I.1. Getting The Source via Git
    • J. 文件取得
    • K. PostgreSQL Limits
    • L. 縮寫字
    • M. Glossary
    • N. 色彩支援
      • N.1. When Color is Used
      • N.2. Configuring the Colors
  • 參考書目
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  • F.33.1. FDW Options of postgres_fdw
  • F.33.1.1. Connection Options
  • F.33.1.2. Object Name Options
  • F.33.1.3. Cost Estimation Options
  • F.33.1.4. Remote Execution Options
  • F.33.1.5. Updatability Options
  • F.33.1.6. Importing Options
  • F.33.2. Connection Management
  • F.33.3. Transaction Management
  • F.33.4. Remote Query Optimization
  • F.33.5. Remote Query Execution Environment
  • F.33.6. Cross-Version Compatibility
  • F.33.7. 範例
  • F.33.8. 作者

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  1. VIII. 附錄
  2. F. 延伸支援模組

F.33. postgres_fdw

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Last updated 3 years ago

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postgres_fdw 模組提供了外部資料封裝器 postgres_fdw,可用於存取儲存在外部 PostgreSQL 伺服器中的資料。

此模組提供的功能與舊版 dblink 模組的功能基本上是重疊的。但是 postgres_fdw 提供了更直覺且符合標準的語法來存取遠端資料表,並且在許多情況下可以提供更好的效能。

要準備使用 postgres_fdw 進行遠端存取:

  1. 使用 安裝 postgres_fdw 延伸功能。

  2. 使用 CREATE SERVER 建立一個外部伺服器物件,設定您要連線的每個遠端資料庫。將連線資訊(使用者名稱和密碼除外)指定為 SERVER 物件的選項。

  3. 使用 為要存取每個外部伺服器的每個資料庫使用者建立一個使用者對應。指定用作使用者對應的使用者和密碼選項的遠端使用者名稱和密碼。

  4. 使用 或 為要存取的每個遠端資料表建立一個外部資料表。外部資料表的欄位必須與引用的遠端資料表相符。但是,如果您指定正確的遠端名稱作為外部資料表物件的選項,則可以使用與遠端資料不同的資料表名稱和欄位名稱。

現在,您只需要從外部資料表中執行 SELECT 即可存取儲存在遠端的基本資料表中的資料。您還可以使用 INSERT、UPDATE 或 DELETE 來修改遠端資料表。 (當然,您在 USER MAPPING 中所指定的遠端使用者必須具有執行這些操作的權限。)

請注意,postgres_fdw 目前不支援帶有 ON CONFLICT DO UPDATE 子句的 INSERT 語句。但是,支援 ON CONFLICT DO NOTHING 子句,唯一性衝突處理宣告將會被忽略。還要注意,postgres_fdw 支援在分割資料表上執行的 UPDATE 語句所呼叫的資料遷移,但是目前不能處理以下情況:選擇將插入資料的遠端分割區也剛好是後續要 UPDATE 的目標分割區。

通常建議使用與遠端資料表欄位完全相同的資料型別和排序規則來宣告外部資料表的欄位。儘管 postgres_fdw 目前相當寬容地根據需要執行資料型別轉換,但是當型別或排序規則不符合時,由於遠端伺服器對 WHERE 子句的解釋與本機伺服器的解釋略有不同,因此可能會出現令人驚訝的語義結果。

請注意,與基本遠端資料表相比,可以用更少的欄位或不同的欄位順序宣告一個外部資料表。欄位與遠端資料表的對應是按名稱而不是位置進行的。

F.33.1. FDW Options of postgres_fdw

F.33.1.1. Connection Options

A foreign server using the postgres_fdw foreign data wrapper can have the same options that libpq accepts in connection strings, as described in , except that these options are not allowed or have special handling:

  • user, password and sslpassword (specify these in a user mapping, instead, or use a service file)

  • client_encoding (this is automatically set from the local server encoding)

  • fallback_application_name (always set to postgres_fdw)

  • sslkey and sslcert - these may appear in either or both a connection and a user mapping. If both are present, the user mapping setting overrides the connection setting.

Only superusers may create or modify user mappings with the sslcert or sslkey settings.

Only superusers may connect to foreign servers without password authentication, so always specify the password option for user mappings belonging to non-superusers.

A superuser may override this check on a per-user-mapping basis by setting the user mapping option password_required 'false', e.g.,

ALTER USER MAPPING FOR some_non_superuser SERVER loopback_nopw
OPTIONS (ADD password_required 'false');

To prevent unprivileged users from exploiting the authentication rights of the unix user the postgres server is running as to escalate to superuser rights, only the superuser may set this option on a user mapping.

Care is required to ensure that this does not allow the mapped user the ability to connect as superuser to the mapped database per CVE-2007-3278 and CVE-2007-6601. Don't set password_required=false on the public role. Keep in mind that the mapped user can potentially use any client certificates, .pgpass, .pg_service.conf etc in the unix home directory of the system user the postgres server runs as. They can also use any trust relationship granted by authentication modes like peer or ident authentication.

F.33.1.2. Object Name Options

These options can be used to control the names used in SQL statements sent to the remote PostgreSQL server. These options are needed when a foreign table is created with names different from the underlying remote table's names.

schema_name

This option, which can be specified for a foreign table, gives the schema name to use for the foreign table on the remote server. If this option is omitted, the name of the foreign table's schema is used.

table_name

This option, which can be specified for a foreign table, gives the table name to use for the foreign table on the remote server. If this option is omitted, the foreign table's name is used.

column_name

This option, which can be specified for a column of a foreign table, gives the column name to use for the column on the remote server. If this option is omitted, the column's name is used.

F.33.1.3. Cost Estimation Options

postgres_fdw retrieves remote data by executing queries against remote servers, so ideally the estimated cost of scanning a foreign table should be whatever it costs to be done on the remote server, plus some overhead for communication. The most reliable way to get such an estimate is to ask the remote server and then add something for overhead — but for simple queries, it may not be worth the cost of an additional remote query to get a cost estimate. So postgres_fdw provides the following options to control how cost estimation is done:

use_remote_estimate

This option, which can be specified for a foreign table or a foreign server, controls whether postgres_fdw issues remote EXPLAIN commands to obtain cost estimates. A setting for a foreign table overrides any setting for its server, but only for that table. The default is false.

fdw_startup_cost

This option, which can be specified for a foreign server, is a numeric value that is added to the estimated startup cost of any foreign-table scan on that server. This represents the additional overhead of establishing a connection, parsing and planning the query on the remote side, etc. The default value is 100.

fdw_tuple_cost

This option, which can be specified for a foreign server, is a numeric value that is used as extra cost per-tuple for foreign-table scans on that server. This represents the additional overhead of data transfer between servers. You might increase or decrease this number to reflect higher or lower network delay to the remote server. The default value is 0.01.

F.33.1.4. Remote Execution Options

By default, only WHERE clauses using built-in operators and functions will be considered for execution on the remote server. Clauses involving non-built-in functions are checked locally after rows are fetched. If such functions are available on the remote server and can be relied on to produce the same results as they do locally, performance can be improved by sending such WHERE clauses for remote execution. This behavior can be controlled using the following option:

extensions

This option is a comma-separated list of names of PostgreSQL extensions that are installed, in compatible versions, on both the local and remote servers. Functions and operators that are immutable and belong to a listed extension will be considered shippable to the remote server. This option can only be specified for foreign servers, not per-table.

When using the extensions option, it is the user's responsibility that the listed extensions exist and behave identically on both the local and remote servers. Otherwise, remote queries may fail or behave unexpectedly.

fetch_size

This option specifies the number of rows postgres_fdw should get in each fetch operation. It can be specified for a foreign table or a foreign server. The option specified on a table overrides an option specified for the server. The default is 100.

F.33.1.5. Updatability Options

By default all foreign tables using postgres_fdw are assumed to be updatable. This may be overridden using the following option:updatable

This option controls whether postgres_fdw allows foreign tables to be modified using INSERT, UPDATE and DELETE commands. It can be specified for a foreign table or a foreign server. A table-level option overrides a server-level option. The default is true.

Of course, if the remote table is not in fact updatable, an error would occur anyway. Use of this option primarily allows the error to be thrown locally without querying the remote server. Note however that the information_schema views will report a postgres_fdw foreign table to be updatable (or not) according to the setting of this option, without any check of the remote server.

F.33.1.6. Importing Options

Importing behavior can be customized with the following options (given in the IMPORT FOREIGN SCHEMA command):

import_collate

This option controls whether column COLLATE options are included in the definitions of foreign tables imported from a foreign server. The default is true. You might need to turn this off if the remote server has a different set of collation names than the local server does, which is likely to be the case if it's running on a different operating system.

import_default

This option controls whether column DEFAULT expressions are included in the definitions of foreign tables imported from a foreign server. The default is false. If you enable this option, be wary of defaults that might get computed differently on the local server than they would be on the remote server; nextval() is a common source of problems. The IMPORT will fail altogether if an imported default expression uses a function or operator that does not exist locally.

import_not_null

This option controls whether column NOT NULL constraints are included in the definitions of foreign tables imported from a foreign server. The default is true.

Tables or foreign tables which are partitions of some other table are automatically excluded. Partitioned tables are imported, unless they are a partition of some other table. Since all data can be accessed through the partitioned table which is the root of the partitioning hierarchy, this approach should allow access to all the data without creating extra objects.

F.33.2. Connection Management

postgres_fdw establishes a connection to a foreign server during the first query that uses a foreign table associated with the foreign server. This connection is kept and re-used for subsequent queries in the same session. However, if multiple user identities (user mappings) are used to access the foreign server, a connection is established for each user mapping.

F.33.3. Transaction Management

During a query that references any remote tables on a foreign server, postgres_fdw opens a transaction on the remote server if one is not already open corresponding to the current local transaction. The remote transaction is committed or aborted when the local transaction commits or aborts. Savepoints are similarly managed by creating corresponding remote savepoints.

The remote transaction uses SERIALIZABLE isolation level when the local transaction has SERIALIZABLE isolation level; otherwise it uses REPEATABLE READ isolation level. This choice ensures that if a query performs multiple table scans on the remote server, it will get snapshot-consistent results for all the scans. A consequence is that successive queries within a single transaction will see the same data from the remote server, even if concurrent updates are occurring on the remote server due to other activities. That behavior would be expected anyway if the local transaction uses SERIALIZABLE or REPEATABLE READ isolation level, but it might be surprising for a READ COMMITTED local transaction. A future PostgreSQL release might modify these rules.

Note that it is currently not supported by postgres_fdw to prepare the remote transaction for two-phase commit.

F.33.4. Remote Query Optimization

postgres_fdw attempts to optimize remote queries to reduce the amount of data transferred from foreign servers. This is done by sending query WHERE clauses to the remote server for execution, and by not retrieving table columns that are not needed for the current query. To reduce the risk of misexecution of queries, WHERE clauses are not sent to the remote server unless they use only data types, operators, and functions that are built-in or belong to an extension that's listed in the foreign server's extensions option. Operators and functions in such clauses must be IMMUTABLE as well. For an UPDATE or DELETE query, postgres_fdw attempts to optimize the query execution by sending the whole query to the remote server if there are no query WHERE clauses that cannot be sent to the remote server, no local joins for the query, no row-level local BEFORE or AFTER triggers or stored generated columns on the target table, and no CHECK OPTION constraints from parent views. In UPDATE, expressions to assign to target columns must use only built-in data types, IMMUTABLE operators, or IMMUTABLE functions, to reduce the risk of misexecution of the query.

When postgres_fdw encounters a join between foreign tables on the same foreign server, it sends the entire join to the foreign server, unless for some reason it believes that it will be more efficient to fetch rows from each table individually, or unless the table references involved are subject to different user mappings. While sending the JOIN clauses, it takes the same precautions as mentioned above for the WHERE clauses.

The query that is actually sent to the remote server for execution can be examined using EXPLAIN VERBOSE.

F.33.5. Remote Query Execution Environment

postgres_fdw likewise establishes remote session settings for various parameters:

These are less likely to be problematic than search_path, but can be handled with function SET options if the need arises.

It is not recommended that you override this behavior by changing the session-level settings of these parameters; that is likely to cause postgres_fdw to malfunction.

F.33.6. Cross-Version Compatibility

postgres_fdw can be used with remote servers dating back to PostgreSQL 8.3. Read-only capability is available back to 8.1. A limitation however is that postgres_fdw generally assumes that immutable built-in functions and operators are safe to send to the remote server for execution, if they appear in a WHERE clause for a foreign table. Thus, a built-in function that was added since the remote server's release might be sent to it for execution, resulting in “function does not exist” or a similar error. This type of failure can be worked around by rewriting the query, for example by embedding the foreign table reference in a sub-SELECT with OFFSET 0 as an optimization fence, and placing the problematic function or operator outside the sub-SELECT.

F.33.7. 範例

這是使用 postgres_fdw 建立一個外部資料表的範例。 首先安裝延伸功能:

CREATE EXTENSION postgres_fdw;
CREATE SERVER foreign_server
        FOREIGN DATA WRAPPER postgres_fdw
        OPTIONS (host '192.83.123.89', port '5432', dbname 'foreign_db');
CREATE USER MAPPING FOR local_user
        SERVER foreign_server
        OPTIONS (user 'foreign_user', password 'password');
CREATE FOREIGN TABLE foreign_table (
        id integer NOT NULL,
        data text
)
        SERVER foreign_server
        OPTIONS (schema_name 'some_schema', table_name 'some_table');

F.33.8. 作者

When use_remote_estimate is true, postgres_fdw obtains row count and cost estimates from the remote server and then adds fdw_startup_cost and fdw_tuple_cost to the cost estimates. When use_remote_estimate is false, postgres_fdw performs local row count and cost estimation and then adds fdw_startup_cost and fdw_tuple_cost to the cost estimates. This local estimation is unlikely to be very accurate unless local copies of the remote table's statistics are available. Running on the foreign table is the way to update the local statistics; this will perform a scan of the remote table and then calculate and store statistics just as though the table were local. Keeping local statistics can be a useful way to reduce per-query planning overhead for a remote table — but if the remote table is frequently updated, the local statistics will soon be obsolete.

postgres_fdw is able to import foreign table definitions using . This command creates foreign table definitions on the local server that match tables or views present on the remote server. If the remote tables to be imported have columns of user-defined data types, the local server must have compatible types of the same names.

Note that constraints other than NOT NULL will never be imported from the remote tables. Although PostgreSQL does support CHECK constraints on foreign tables, there is no provision for importing them automatically, because of the risk that a constraint expression could evaluate differently on the local and remote servers. Any such inconsistency in the behavior of a CHECK constraint could lead to hard-to-detect errors in query optimization. So if you wish to import CHECK constraints, you must do so manually, and you should verify the semantics of each one carefully. For more detail about the treatment of CHECK constraints on foreign tables, see .

In the remote sessions opened by postgres_fdw, the parameter is set to just pg_catalog, so that only built-in objects are visible without schema qualification. This is not an issue for queries generated by postgres_fdw itself, because it always supplies such qualification. However, this can pose a hazard for functions that are executed on the remote server via triggers or rules on remote tables. For example, if a remote table is actually a view, any functions used in that view will be executed with the restricted search path. It is recommended to schema-qualify all names in such functions, or else attach SET search_path options (see ) to such functions to establish their expected search path environment.

is set to UTC

is set to ISO

is set to postgres

is set to 3 for remote servers 9.0 and newer and is set to 2 for older versions

然後使用 建立一個外部伺服器。在此範例中,我們希望連線到主機 192.83.123.89 上連接埠為 5432 的 PostgreSQL 伺服器。該伺服器建立連線的資料庫,在遠端伺服器上的名稱為 foreign_db:

還需要使用 定義的使用者對應,以標示將在遠端伺服器上所使用的角色:

現在可以用 建立一個外部資料表。在此範例中,我們希望存取遠端伺服器上名為 some_schema.some_table 的資料表。它在本機的名稱將為 foreign_table:

在 CREATE FOREIGN TABLE 中宣告的欄位資料型別和其他屬性必須與實際遠端的資料表相符。欄位名稱也必須相符,除非您將 column_name 選項附加到各個欄位以表示它們在遠端資料表中的命名方式。在許多情況下,使用 優於手動建構外部資料表定義。

Shigeru Hanada <>

CREATE EXTENSION
CREATE USER MAPPING
CREATE FOREIGN TABLE
IMPORT FOREIGN SCHEMA
Section 33.1.2
ANALYZE
IMPORT FOREIGN SCHEMA
CREATE FOREIGN TABLE
search_path
CREATE FUNCTION
TimeZone
DateStyle
IntervalStyle
extra_float_digits
CREATE SERVER
CREATE USER MAPPING
CREATE FOREIGN TABLE
IMPORT FOREIGN SCHEMA
shigeru.hanada@gmail.com