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前言 何为PostgreSQL? PostgreSQL简史 格式约定 更多信息 臭虫汇报指导 I. 教程 章1. 从头开始 1.1. 安装 1.2. 体系基本概念 1.3. 创建一个数据库 1.4. 访问数据库 章2. SQL语言 2.1. 介绍 2.2. 概念 2.3. 创建新表 2.4. 向表中添加行 2.5. 查询一个表 2.6. 表间链接 2.7. 聚集函数 2.8. 更新 2.9. 删除 章3. 高级特性 3.1. 介绍 3.2. 视图 3.3. 外键 3.4. 事务 3.5. 窗口函数 3.6. 继承 3.7. 结论 II. SQL语言 章4. SQL语法 4.1. 词法结构 4.2. 值表达式 4.3. 调用函数 章5. 数据定义 5.1. 表的基本概念 5.2. 缺省值 5.3. 约束 5.4. 系统字段 5.5. 修改表 5.6. 权限 5.7. 模式 5.8. 继承 5.9. 分区 5.10. 其它数据库对象 5.11. 依赖性跟踪 章 6. 数据操作 6.1. 插入数据 6.2. 更新数据 6.3. 删除数据 章7. 查询 7.1. 概述 7.2. 表表达式 7.3. 选择列表 7.4. 组合查询 7.5. 行排序 7.6. LIMIT和OFFSET 7.7. VALUES列表 7.8. WITH的查询(公用表表达式) 章8. 数据类型 8.1. 数值类型 8.2. 货币类型 8.3. 字符类型 8.4. 二进制数据类型 8.5. 日期/时间类型 8.6. 布尔类型 8.7. 枚举类型 8.8. 几何类型 8.9. 网络地址类型 8.10. 位串类型 8.11. 文本搜索类型 8.12. UUID类型 8.13. XML类型 8.14. 数组 8.15. 复合类型 8.16. 对象标识符类型 8.17. 伪类型 章 9. 函数和操作符 9.1. 逻辑操作符 9.2. 比较操作符 9.3. 数学函数和操作符 9.4. 字符串函数和操作符 9.5. 二进制字符串函数和操作符 9.6. 位串函数和操作符 9.7. 模式匹配 9.8. 数据类型格式化函数 9.9. 时间/日期函数和操作符 9.10. 支持枚举函数 9.11. 几何函数和操作符 9.12. 网络地址函数和操作符 9.13. 文本检索函数和操作符 9.14. XML函数 9.15. 序列操作函数 9.16. 条件表达式 9.17. 数组函数和操作符 9.18. 聚合函数 9.19. 窗口函数 9.20. 子查询表达式 9.21. 行和数组比较 9.22. 返回集合的函数 9.23. 系统信息函数 9.24. 系统管理函数 9.25. 触发器函数 章10. 类型转换 10.3. 函数 10.2. 操作符 10.1. 概述 10.4. 值存储 10.5. UNION 章11. 索引 11.1. 介绍 11.2. 索引类型 11.3. 多字段索引 11.4. 索引和ORDER BY 11.5. 组合多个索引 11.6. 唯一索引 11.7. 表达式上的索引 11.8. 部分索引 11.9. 操作类和操作簇 11.10. 检查索引的使用 章12. Full Text Search 12.1. Introduction 12.2. Tables and Indexes 12.3. Controlling Text Search 12.4. Additional Features 12.5. Parsers 12.6. Dictionaries 12.7. Configuration Example 12.8. Testing and Debugging Text Search 12.9. GiST and GIN Index Types 12.10. psql Support 12.11. Limitations 12.12. Migration from Pre-8.3 Text Search 章13. 并发控制 13.1. 介绍 13.2. 事务隔离 13.3. 明确锁定 13.4. 应用层数据完整性检查 13.5. 锁和索引 章14. 性能提升技巧 14.1. 使用EXPLAIN 14.2. 规划器使用的统计信息 14.3. 用明确的JOIN语句控制规划器 14.4. 向数据库中添加记录 14.5. 非持久性设置 III. 服务器管理 章15. 安装指导 15.1. 简版 15.2. 要求 15.3. 获取源码 15.4. 升级 15.5. 安装过程 15.6. 安装后的设置 15.7. 支持的平台 15.8. 特殊平台的要求 章16. Installation from Source Code on Windows 16.1. Building with Visual C++ or the Platform SDK 16.2. Building libpq with Visual C++ or Borland C++ 章17. 服务器安装和操作 17.1. PostgreSQL用户帐户 17.2. 创建数据库集群 17.3. 启动数据库服务器 17.4. 管理内核资源 17.5. 关闭服务 17.6. 防止服务器欺骗 17.7. 加密选项 17.8. 用SSL进行安全的TCP/IP连接 17.9. Secure TCP/IP Connections with SSH Tunnels 章18. 服务器配置 18.1. 设置参数 18.2. 文件位置 18.3. 连接和认证 18.4. 资源消耗 18.5. 预写式日志 18.6. 查询规划 18.7. 错误报告和日志 18.8. 运行时统计 18.9. 自动清理 18.10. 客户端连接缺省 18.12. 版本和平台兼容性 18.11. 锁管理 18.13. 预置选项 18.14. 自定义的选项 18.15. 开发人员选项 18.16. 短选项 章19. 用户认证 19.1. pg_hba.conf 文件 19.2. 用户名映射 19.3. 认证方法 19.4. 用户认证 章20. 数据库角色和权限 20.1. 数据库角色 20.2. 角色属性 20.3. 权限 20.4. 角色成员 20.5. 函数和触发器 章21. 管理数据库 21.1. 概述 21.2. 创建一个数据库 21.3. 临时库 21.4. 数据库配置 21.5. 删除数据库 21.6. 表空间 章22. 本土化 22.1. 区域支持 22.2. 字符集支持 章23. 日常数据库维护工作 23.1. Routine Vacuuming日常清理 23.2. 经常重建索引 23.3. 日志文件维护 章24. 备份和恢复 24.1. SQL转储 24.2. 文件系统级别的备份 24.3. 在线备份以及即时恢复(PITR) 24.4. 版本间迁移 章25. 高可用性与负载均衡,复制 25.1. 不同解决方案的比较 25.2. 日志传送备份服务器 25.3. 失效切换 25.4. 日志传送的替代方法 25.5. 热备 章26. 恢复配置 26.1. 归档恢复设置 26.2. 恢复目标设置 26.3. 备服务器设置 章27. 监控数据库的活动 27.1. 标准Unix工具 27.2. 统计收集器 27.3. 查看锁 27.4. 动态跟踪 章28. 监控磁盘使用情况 28.1. 判断磁盘的使用量 28.2. 磁盘满导致的失效 章29. 可靠性和预写式日志 29.1. 可靠性 29.2. 预写式日志(WAL) 29.3. 异步提交 29.4. WAL配置 29.5. WAL内部 章30. Regression Tests 30.1. Running the Tests 30.2. Test Evaluation 30.3. Variant Comparison Files 30.4. Test Coverage Examination IV. 客户端接口 章31. libpq-C库 31.1. 数据库联接函数 31.2. 连接状态函数 31.3. 命令执行函数 31.4. 异步命令处理 31.5. 取消正在处理的查询 31.6. 捷径接口 31.7. 异步通知 31.8. 与COPY命令相关的函数 31.9. Control Functions 控制函数 31.10. 其他函数 31.11. 注意信息处理 31.12. 事件系统 31.13. 环境变量 31.14. 口令文件 31.15. 连接服务的文件 31.16. LDAP查找连接参数 31.17. SSL支持 31.18. 在多线程程序里的行为 31.19. 制作libpq程序 31.20. 例子程序 章32. 大对象 32.1. 介绍 32.2. 实现特点 32.3. 客户端接口 32.4. 服务器端函数 32.5. 例子程序 章33. ECPG - Embedded SQL in C 33.1. The Concept 33.2. Connecting to the Database Server 33.3. Closing a Connection 33.4. Running SQL Commands 33.5. Choosing a Connection 33.6. Using Host Variables 33.7. Dynamic SQL 33.8. pgtypes library 33.9. Using Descriptor Areas 33.10. Informix compatibility mode 33.11. Error Handling 33.12. Preprocessor directives 33.13. Processing Embedded SQL Programs 33.14. Library Functions 33.15. Internals 章34. 信息模式 34.1. 关于这个模式 34.2. 数据类型 34.3. information_schema_catalog_name 34.4. administrable_role_authorizations 34.5. applicable_roles 34.6. attributes 34.7. check_constraint_routine_usage 34.8. check_constraints 34.9. column_domain_usage 34.10. column_privileges 34.11. column_udt_usage 34.12. 字段 34.13. constraint_column_usage 34.14. constraint_table_usage 34.15. data_type_privileges 34.16. domain_constraints 34.18. domains 34.17. domain_udt_usage 34.19. element_types 34.20. enabled_roles 34.21. foreign_data_wrapper_options 34.22. foreign_data_wrappers 34.23. foreign_server_options 34.24. foreign_servers 34.25. key_column_usage 34.26. parameters 34.27. referential_constraints 34.28. role_column_grants 34.29. role_routine_grants 34.30. role_table_grants 34.31. role_usage_grants 34.32. routine_privileges 34.33. routines 34.34. schemata 34.35. sequences 34.36. sql_features 34.37. sql_implementation_info 34.38. sql_languages 34.39. sql_packages 34.40. sql_parts 34.41. sql_sizing 34.42. sql_sizing_profiles 34.43. table_constraints 34.44. table_privileges 34.45. tables 34.46. triggered_update_columns 34.47. 触发器 34.48. usage_privileges 34.49. user_mapping_options 34.50. user_mappings 34.51. view_column_usage 34.52. view_routine_usage 34.53. view_table_usage 34.54. 视图 V. 服务器端编程 章35. 扩展SQL 35.1. 扩展性是如何实现的 35.2. PostgreSQL类型系统 35.3. User-Defined Functions 35.4. Query Language (SQL) Functions 35.5. Function Overloading 35.6. Function Volatility Categories 35.7. Procedural Language Functions 35.8. Internal Functions 35.9. C-Language Functions 35.10. User-Defined Aggregates 35.11. User-Defined Types 35.12. User-Defined Operators 35.13. Operator Optimization Information 35.14. Interfacing Extensions To Indexes 35.15. 用C++扩展 章36. 触发器 36.1. 触发器行为概述 36.3. 用 C 写触发器 36.2. 数据改变的可视性 36.4. 一个完整的例子 章37. 规则系统 37.1. The Query Tree 37.2. 视图和规则系统 37.3. 在INSERT,UPDATE和DELETE上的规则 37.4. 规则和权限 37.5. 规则和命令状态 37.6. 规则与触发器得比较 章38. Procedural Languages 38.1. Installing Procedural Languages 章39. PL/pgSQL - SQL过程语言 39.1. 概述 39.2. PL/pgSQL的结构 39.3. 声明 39.4. 表达式 39.5. 基本语句 39.6. 控制结构 39.7. 游标 39.8. 错误和消息 39.9. 触发器过程 39.10. PL/pgSQL Under the Hood 39.11. 开发PL/pgSQL的一些提示 39.12. 从OraclePL/SQL 进行移植 章40. PL/Tcl - Tcl Procedural Language 40.1. Overview 40.2. PL/Tcl Functions and Arguments 40.3. Data Values in PL/Tcl 40.4. Global Data in PL/Tcl 40.5. Database Access from PL/Tcl 40.6. Trigger Procedures in PL/Tcl 40.7. Modules and the unknown command 40.8. Tcl Procedure Names 章41. PL/Perl - Perl Procedural Language 41.1. PL/Perl Functions and Arguments 41.2. Data Values in PL/Perl 41.3. Built-in Functions 41.4. Global Values in PL/Perl 41.6. PL/Perl Triggers 41.5. Trusted and Untrusted PL/Perl 41.7. PL/Perl Under the Hood 章42. PL/Python - Python Procedural Language 42.1. Python 2 vs. Python 3 42.2. PL/Python Functions 42.3. Data Values 42.4. Sharing Data 42.5. Anonymous Code Blocks 42.6. Trigger Functions 42.7. Database Access 42.8. Utility Functions 42.9. Environment Variables 章43. Server Programming Interface 43.1. Interface Functions Spi-spi-connect Spi-spi-finish Spi-spi-push Spi-spi-pop Spi-spi-execute Spi-spi-exec Spi-spi-execute-with-args Spi-spi-prepare Spi-spi-prepare-cursor Spi-spi-prepare-params Spi-spi-getargcount Spi-spi-getargtypeid Spi-spi-is-cursor-plan Spi-spi-execute-plan Spi-spi-execute-plan-with-paramlist Spi-spi-execp Spi-spi-cursor-open Spi-spi-cursor-open-with-args Spi-spi-cursor-open-with-paramlist Spi-spi-cursor-find Spi-spi-cursor-fetch Spi-spi-cursor-move Spi-spi-scroll-cursor-fetch Spi-spi-scroll-cursor-move Spi-spi-cursor-close Spi-spi-saveplan 43.2. Interface Support Functions Spi-spi-fname Spi-spi-fnumber Spi-spi-getvalue Spi-spi-getbinval Spi-spi-gettype Spi-spi-gettypeid Spi-spi-getrelname Spi-spi-getnspname 43.3. Memory Management Spi-spi-palloc Spi-realloc Spi-spi-pfree Spi-spi-copytuple Spi-spi-returntuple Spi-spi-modifytuple Spi-spi-freetuple Spi-spi-freetupletable Spi-spi-freeplan 43.4. Visibility of Data Changes 43.5. Examples VI. 参考手册 I. SQL命令 Sql-abort Sql-alteraggregate Sql-alterconversion Sql-alterdatabase Sql-alterdefaultprivileges Sql-alterdomain Sql-alterforeigndatawrapper Sql-alterfunction Sql-altergroup Sql-alterindex Sql-alterlanguage Sql-alterlargeobject Sql-alteroperator Sql-alteropclass Sql-alteropfamily Sql-alterrole Sql-alterschema Sql-altersequence Sql-alterserver Sql-altertable Sql-altertablespace Sql-altertsconfig Sql-altertsdictionary Sql-altertsparser Sql-altertstemplate Sql-altertrigger Sql-altertype Sql-alteruser Sql-alterusermapping Sql-alterview Sql-analyze Sql-begin Sql-checkpoint Sql-close Sql-cluster Sql-comment Sql-commit Sql-commit-prepared Sql-copy Sql-createaggregate Sql-createcast Sql-createconstraint Sql-createconversion Sql-createdatabase Sql-createdomain Sql-createforeigndatawrapper Sql-createfunction Sql-creategroup Sql-createindex Sql-createlanguage Sql-createoperator Sql-createopclass Sql-createopfamily Sql-createrole Sql-createrule Sql-createschema Sql-createsequence Sql-createserver Sql-createtable Sql-createtableas Sql-createtablespace Sql-createtsconfig Sql-createtsdictionary Sql-createtsparser Sql-createtstemplate Sql-createtrigger Sql-createtype Sql-createuser Sql-createusermapping Sql-createview Sql-deallocate Sql-declare Sql-delete Sql-discard Sql-do Sql-dropaggregate Sql-dropcast Sql-dropconversion Sql-dropdatabase Sql-dropdomain Sql-dropforeigndatawrapper Sql-dropfunction Sql-dropgroup Sql-dropindex Sql-droplanguage Sql-dropoperator Sql-dropopclass Sql-dropopfamily Sql-drop-owned Sql-droprole Sql-droprule Sql-dropschema Sql-dropsequence Sql-dropserver Sql-droptable Sql-droptablespace Sql-droptsconfig Sql-droptsdictionary Sql-droptsparser Sql-droptstemplate Sql-droptrigger Sql-droptype Sql-dropuser Sql-dropusermapping Sql-dropview Sql-end Sql-execute Sql-explain Sql-fetch Sql-grant Sql-insert Sql-listen Sql-load Sql-lock Sql-move Sql-notify Sql-prepare Sql-prepare-transaction Sql-reassign-owned Sql-reindex Sql-release-savepoint Sql-reset Sql-revoke Sql-rollback Sql-rollback-prepared Sql-rollback-to Sql-savepoint Sql-select Sql-selectinto Sql-set Sql-set-constraints Sql-set-role Sql-set-session-authorization Sql-set-transaction Sql-show Sql-start-transaction Sql-truncate Sql-unlisten Sql-update Sql-vacuum Sql-values II. 客户端应用程序 App-clusterdb App-createdb App-createlang App-createuser App-dropdb App-droplang App-dropuser App-ecpg App-pgconfig App-pgdump App-pg-dumpall App-pgrestore App-psql App-reindexdb App-vacuumdb III. PostgreSQL服务器应用程序 App-initdb App-pgcontroldata App-pg-ctl App-pgresetxlog App-postgres App-postmaster VII. 内部 章44. PostgreSQL内部概览 44.1. 查询路径 44.2. 连接是如何建立起来的 44.3. 分析器阶段 44.4. ThePostgreSQL规则系统 44.5. 规划器/优化器 44.6. 执行器 章45. 系统表 45.1. 概述 45.2. pg_aggregate 45.3. pg_am 45.4. pg_amop 45.5. pg_amproc 45.6. pg_attrdef 45.7. pg_attribute 45.8. pg_authid 45.9. pg_auth_members 45.10. pg_cast 45.11. pg_class 45.12. pg_constraint 45.13. pg_conversion 45.14. pg_database 45.15. pg_db_role_setting 45.16. pg_default_acl 45.17. pg_depend 45.18. pg_description 45.19. pg_enum 45.20. pg_foreign_data_wrapper 45.21. pg_foreign_server 45.22. pg_index 45.23. pg_inherits 45.24. pg_language 45.25. pg_largeobject 45.26. pg_largeobject_metadata 45.27. pg_namespace 45.28. pg_opclass 45.29. pg_operator 45.30. pg_opfamily 45.31. pg_pltemplate 45.32. pg_proc 45.33. pg_rewrite 45.34. pg_shdepend 45.35. pg_shdescription 45.36. pg_statistic 45.37. pg_tablespace 45.38. pg_trigger 45.39. pg_ts_config 45.40. pg_ts_config_map 45.41. pg_ts_dict 45.42. pg_ts_parser 45.43. pg_ts_template 45.44. pg_type 45.45. pg_user_mapping 45.46. System Views 45.47. pg_cursors 45.48. pg_group 45.49. pg_indexes 45.50. pg_locks 45.51. pg_prepared_statements 45.52. pg_prepared_xacts 45.53. pg_roles 45.54. pg_rules 45.55. pg_settings 45.56. pg_shadow 45.57. pg_stats 45.58. pg_tables 45.59. pg_timezone_abbrevs 45.60. pg_timezone_names 45.61. pg_user 45.62. pg_user_mappings 45.63. pg_views 章46. Frontend/Backend Protocol 46.1. Overview 46.2. Message Flow 46.3. Streaming Replication Protocol 46.4. Message Data Types 46.5. Message Formats 46.6. Error and Notice Message Fields 46.7. Summary of Changes since Protocol 2.0 47. PostgreSQL Coding Conventions 47.1. Formatting 47.2. Reporting Errors Within the Server 47.3. Error Message Style Guide 章48. Native Language Support 48.1. For the Translator 48.2. For the Programmer 章49. Writing A Procedural Language Handler 章50. Genetic Query Optimizer 50.1. Query Handling as a Complex Optimization Problem 50.2. Genetic Algorithms 50.3. Genetic Query Optimization (GEQO) in PostgreSQL 50.4. Further Reading 章51. 索引访问方法接口定义 51.1. 索引的系统表记录 51.2. 索引访问方法函数 51.3. 索引扫描 51.4. 索引锁的考量 51.5. 索引唯一性检查 51.6. 索引开销估计函数 章52. GiST Indexes 52.1. Introduction 52.2. Extensibility 52.3. Implementation 52.4. Examples 52.5. Crash Recovery 章53. GIN Indexes 53.1. Introduction 53.2. Extensibility 53.3. Implementation 53.4. GIN tips and tricks 53.5. Limitations 53.6. Examples 章54. 数据库物理存储 54.1. 数据库文件布局 54.2. TOAST 54.3. 自由空间映射 54.4. 可见映射 54.5. 数据库分页文件 章55. BKI后端接口 55.1. BKI 文件格式 55.2. BKI命令 55.3. 系统初始化的BKI文件的结构 55.4. 例子 章56. 规划器如何使用统计信息 56.1. 行预期的例子 VIII. 附录 A. PostgreSQL错误代码 B. 日期/时间支持 B.1. 日期/时间输入解析 B.2. 日期/时间关键字 B.3. 日期/时间配置文件 B.4. 日期单位的历史 C. SQL关键字 D. SQL Conformance D.1. Supported Features D.2. Unsupported Features E. 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E.5. Release 9.0

Release Date: 2010-09-20

E.5.1. Overview

This release of PostgreSQL adds features that have been requested for years, such as easy-to-use replication, a mass permission-changing facility, and anonymous code blocks. While past major releases have been conservative in their scope, this release shows a bold new desire to provide facilities that new and existing users of PostgreSQL will embrace. This has all been done with few incompatibilities. Major enhancements include:

  • Built-in replication based on log shipping. This advance consists of two features: Streaming Replication, allowing continuous archive (WAL) files to be streamed over a network connection to a standby server, and Hot Standby, allowing continuous archive standby servers to execute read-only queries. The net effect is to support a single master with multiple read-only slave servers.

  • Easier database object permissions management. GRANT/REVOKE IN SCHEMA supports mass permissions changes on existing objects, while ALTER DEFAULT PRIVILEGES allows control of privileges for objects created in the future. Large objects (BLOBs) now support permissions management as well.

  • Broadly enhanced stored procedure support. The DO statement supports ad-hoc or "anonymous" code blocks. Functions can now be called using named parameters. PL/pgSQL is now installed by default, and PL/Perl and PL/Python have been enhanced in several ways, including support for Python3.

  • Full support for 64-bit Windows .

  • More advanced reporting queries, including additional windowing options (PRECEDING and FOLLOWING) and the ability to control the order in which values are fed to aggregate functions.

  • New trigger features, including SQL-standard-compliant per-column triggers and conditional trigger execution.

  • Deferrable unique constraints. Mass updates to unique keys are now possible without trickery.

  • Exclusion constraints. These provide a generalized version of unique constraints, allowing enforcement of complex conditions.

  • New and enhanced security features, including RADIUS authentication, LDAP authentication improvements, and a new contrib module passwordcheck for testing password strength.

  • New high-performance implementation of the LISTEN/NOTIFY feature. Pending events are now stored in a memory-based queue rather than a table. Also, a "payload" string can be sent with each event, rather than transmitting just an event name as before.

  • New implementation of VACUUM FULL. This command now rewrites the entire table and indexes, rather than moving individual rows to compact space. It is substantially faster in most cases, and no longer results in index bloat.

  • New contrib module pg_upgrade to support in-place upgrades from 8.3 or 8.4 to 9.0.

  • Multiple performance enhancements for specific types of queries, including elimination of unnecessary joins. This helps optimize some automatically-generated queries, such as those produced by object-relational mappers (ORMs).

  • EXPLAIN enhancements. The output is now available in JSON, XML, or YAML format, and includes buffer utilization and other data not previously available.

  • hstore improvements, including new functions and greater data capacity.

The above items are explained in more detail in the sections below.

E.5.2. Migration to Version 9.0

A dump/restore using pg_dump, or use of pg_upgrade, is required for those wishing to migrate data from any previous release.

Version 9.0 contains a number of changes that selectively break backwards compatibility in order to support new features and code quality improvements. In particular, users who make extensive use of PL/pgSQL, Point-In-Time Recovery (PITR), or Warm Standby should test their applications because of slight user-visible changes in those areas. Observe the following incompatibilities:

E.5.2.1. Server Settings

  • Remove server parameter add_missing_from, which was defaulted to off for many years (Tom Lane)

  • Remove server parameter regex_flavor, which was defaulted to advanced for many years (Tom Lane)

  • archive_mode now only affects archive_command; a new setting, wal_level, affects the contents of the write-ahead log (Heikki Linnakangas)

  • log_temp_files now uses default file size units of kilobytes (Robert Haas)

E.5.2.2. Queries

  • When querying a parent table, do not do any separate permission checks on child tables scanned as part of the query (Peter Eisentraut)

    The SQL standard specifies this behavior, and it is also much more convenient in practice than the former behavior of checking permissions on each child as well as the parent.

E.5.2.3. Data Types

  • bytea output now appears in hex format by default (Peter Eisentraut)

    The server parameter bytea_output can be used to select the traditional output format if needed for compatibility.

  • Array input now considers only plain ASCII whitespace characters to be potentially ignorable; it will never ignore non-ASCII characters, even if they are whitespace according to some locales (Tom Lane)

    This avoids some corner cases where array values could be interpreted differently depending on the server's locale settings.

  • Improve standards compliance of SIMILAR TO patterns and SQL-style substring() patterns (Tom Lane)

    This includes treating ? and {...} as pattern metacharacters, while they were simple literal characters before; that corresponds to new features added in SQL:2008. Also, ^ and $ are now treated as simple literal characters; formerly they were treated as metacharacters, as if the pattern were following POSIX rather than SQL rules. Also, in SQL-standard substring(), use of parentheses for nesting no longer interferes with capturing of a substring. Also, processing of bracket expressions (character classes) is now more standards-compliant.

  • Reject negative length values in 3-parameter substring() for bit strings, per the SQL standard (Tom Lane)

  • Make date_trunc truncate rather than round when reducing precision of fractional seconds (Tom Lane)

    The code always acted this way for integer-based dates/times. Now float-based dates/times behave similarly.

E.5.2.4. Object Renaming

  • Tighten enforcement of column name consistency during RENAME when a child table inherits the same column from multiple unrelated parents (KaiGai Kohei)

  • No longer automatically rename indexes and index columns when the underlying table columns are renamed (Tom Lane)

    Administrators can still rename such indexes and columns manually. This change will require an update of the JDBC driver, and possibly other drivers, so that unique indexes are correctly recognized after a rename.

  • CREATE OR REPLACE FUNCTION can no longer change the declared names of function parameters (Pavel Stehule)

    In order to avoid creating ambiguity in named-parameter calls, it is no longer allowed to change the aliases for input parameters in the declaration of an existing function (although names can still be assigned to previously unnamed parameters). You now have to DROP and recreate the function to do that.

E.5.2.5. PL/pgSQL

  • PL/pgSQL now throws an error if a variable name conflicts with a column name used in a query (Tom Lane)

    The former behavior was to bind ambiguous names to PL/pgSQL variables in preference to query columns, which often resulted in surprising misbehavior. Throwing an error allows easy detection of ambiguous situations. Although it's recommended that functions encountering this type of error be modified to remove the conflict, the old behavior can be restored if necessary via the configuration parameter plpgsql.variable_conflict, or via the per-function option #variable_conflict.

  • PL/pgSQL no longer allows variable names that match certain SQL reserved words (Tom Lane)

    This is a consequence of aligning the PL/pgSQL parser to match the core SQL parser more closely. If necessary, variable names can be double-quoted to avoid this restriction.

  • PL/pgSQL now requires columns of composite results to match the expected type modifier as well as base type (Pavel Stehule, Tom Lane)

    For example, if a column of the result type is declared as NUMERIC(30,2), it is no longer acceptable to return a NUMERIC of some other precision in that column. Previous versions neglected to check the type modifier and would thus allow result rows that didn't actually conform to the declared restrictions.

  • PL/pgSQL now treats selection into composite fields more consistently (Tom Lane)

    Formerly, a statement like SELECT ... INTO rec.fld FROM ... was treated as a scalar assignment even if the record field fld was of composite type. Now it is treated as a record assignment, the same as when the INTO target is a regular variable of composite type. So the values to be assigned to the field's subfields should be written as separate columns of the SELECT list, not as a ROW(...) construct as in previous versions.

    If you need to do this in a way that will work in both 9.0 and previous releases, you can write something like rec.fld := ROW(...) FROM ....

  • Remove PL/pgSQL's RENAME declaration (Tom Lane)

    Instead of RENAME, use ALIAS, which can now create an alias for any variable, not only dollar sign parameter names (such as $1) as before.

E.5.2.6. Other Incompatibilities

  • Deprecate use of => as an operator name (Robert Haas)

    Future versions of PostgreSQL will probably reject this operator name entirely, in order to support the SQL-standard notation for named function parameters. For the moment, it is still allowed, but a warning is emitted when such an operator is defined.

  • Remove support for platforms that don't have a working 64-bit integer data type (Tom Lane)

    It is believed all still-supported platforms have working 64-bit integer data types.

E.5.3. Changes

Version 9.0 has an unprecedented number of new major features, and over 200 enhancements, improvements, new commands, new functions, and other changes.

E.5.3.1. Server

E.5.3.1.1. Continuous Archiving and Streaming Replication

PostgreSQL's existing standby-server capability has been expanded both to support read-only queries on standby servers and to greatly reduce the lag between master and standby servers. For many users, this will be a useful and low-administration form of replication, either for high availability or for horizontal scalability.

  • Allow a standby server to accept read-only queries (Simon Riggs, Heikki Linnakangas)

    This feature is called Hot Standby. There are new postgresql.conf and recovery.conf settings to control this feature, as well as extensive documentation.

  • Allow write-ahead log (WAL) data to be streamed to a standby server (Fujii Masao, Heikki Linnakangas)

    This feature is called Streaming Replication. Previously WAL data could be sent to standby servers only in units of entire WAL files (normally 16 megabytes each). Streaming Replication eliminates this inefficiency and allows updates on the master to be propagated to standby servers with very little delay. There are new postgresql.conf and recovery.conf settings to control this feature, as well as extensive documentation.

  • Add pg_last_xlog_receive_location() and pg_last_xlog_replay_location(), which can be used to monitor standby server WAL activity (Simon Riggs, Fujii Masao, Heikki Linnakangas)

E.5.3.1.2. Performance

  • Allow per-tablespace values to be set for sequential and random page cost estimates (seq_page_cost/random_page_cost) via ALTER TABLESPACE ... SET/RESET (Robert Haas)

  • Improve performance and reliability of EvalPlanQual rechecks in join queries (Tom Lane)

    UPDATE, DELETE, and SELECT FOR UPDATE/SHARE queries that involve joins will now behave much better when encountering freshly-updated rows.

  • Improve performance of TRUNCATE when the table was created or truncated earlier in the same transaction (Tom Lane)

  • Improve performance of finding inheritance child tables (Tom Lane)

E.5.3.1.3. Optimizer

  • Remove unnecessary outer joins (Robert Haas)

    Outer joins where the inner side is unique and not referenced above the join are unnecessary and are therefore now removed. This will accelerate many automatically generated queries, such as those created by object-relational mappers (ORMs).

  • Allow IS NOT NULL restrictions to use indexes (Tom Lane)

    This is particularly useful for finding MAX()/MIN() values in indexes that contain many null values.

  • Improve the optimizer's choices about when to use materialize nodes, and when to use sorting versus hashing for DISTINCT (Tom Lane)

  • Improve the optimizer's equivalence detection for expressions involving boolean <> operators (Tom Lane)

E.5.3.1.4. GEQO

  • Use the same random seed every time GEQO plans a query (Andres Freund)

    While the Genetic Query Optimizer (GEQO) still selects random plans, it now always selects the same random plans for identical queries, thus giving more consistent performance. You can modify geqo_seed to experiment with alternative plans.

  • Improve GEQO plan selection (Tom Lane)

    This avoids the rare error "failed to make a valid plan", and should also improve planning speed.

E.5.3.1.5. Optimizer Statistics

  • Improve ANALYZE to support inheritance-tree statistics (Tom Lane)

    This is particularly useful for partitioned tables. However, autovacuum does not yet automatically re-analyze parent tables when child tables change.

  • Improve autovacuum's detection of when re-analyze is necessary (Tom Lane)

  • Improve optimizer's estimation for greater/less-than comparisons (Tom Lane)

    When looking up statistics for greater/less-than comparisons, if the comparison value is in the first or last histogram bucket, use an index (if available) to fetch the current actual column minimum or maximum. This greatly improves the accuracy of estimates for comparison values near the ends of the data range, particularly if the range is constantly changing due to addition of new data.

  • Allow setting of number-of-distinct-values statistics using ALTER TABLE (Robert Haas)

    This allows users to override the estimated number or percentage of distinct values for a column. This statistic is normally computed by ANALYZE, but the estimate can be poor, especially on tables with very large numbers of rows.

E.5.3.1.6. Authentication

  • Add support for RADIUS (Remote Authentication Dial In User Service) authentication (Magnus Hagander)

  • Allow LDAP (Lightweight Directory Access Protocol) authentication to operate in "search/bind" mode (Robert Fleming, Magnus Hagander)

    This allows the user to be looked up first, then the system uses the DN (Distinguished Name) returned for that user.

  • Add samehost and samenet designations to pg_hba.conf (Stef Walter)

    These match the server's IP address and subnet address respectively.

  • Pass trusted SSL root certificate names to the client so the client can return an appropriate client certificate (Craig Ringer)

E.5.3.1.7. Monitoring

  • Add the ability for clients to set an application name, which is displayed in pg_stat_activity (Dave Page)

    This allows administrators to characterize database traffic and troubleshoot problems by source application.

  • Add a SQLSTATE option (%e) to log_line_prefix (Guillaume Smet)

    This allows users to compile statistics on errors and messages by error code number.

  • Write to the Windows event log in UTF16 encoding (Itagaki Takahiro)

    Now there is true multilingual support for PostgreSQL log messages on Windows.

E.5.3.1.8. Statistics Counters

  • Add pg_stat_reset_shared('bgwriter') to reset the cluster-wide shared statistics for the background writer (Greg Smith)

  • Add pg_stat_reset_single_table_counters() and pg_stat_reset_single_function_counters() to allow resetting the statistics counters for individual tables and functions (Magnus Hagander)

E.5.3.1.9. Server Settings

  • Allow setting of configuration parameters based on database/role combinations (Alvaro Herrera)

    Previously only per-database and per-role settings were possible, not combinations. All role and database settings are now stored in the new pg_db_role_setting system catalog. A new psql command \drds shows these settings. The legacy system views pg_roles, pg_shadow, and pg_user do not show combination settings, and therefore no longer completely represent the configuration for a user or database.

  • Add server parameter bonjour, which controls whether a Bonjour-enabled server advertises itself via Bonjour (Tom Lane)

    The default is off, meaning it does not advertise. This allows packagers to distribute Bonjour-enabled builds without worrying that individual users might not want the feature.

  • Add server parameter enable_material, which controls the use of materialize nodes in the optimizer (Robert Haas)

    The default is on. When off, the optimizer will not add materialize nodes purely for performance reasons, though they will still be used when necessary for correctness.

  • Change server parameter log_temp_files to use default file size units of kilobytes (Robert Haas)

    Previously this setting was interpreted in bytes if no units were specified.

  • Log changes of parameter values when postgresql.conf is reloaded (Peter Eisentraut)

    This lets administrators and security staff audit changes of database settings, and is also very convenient for checking the effects of postgresql.conf edits.

  • Properly enforce superuser permissions for custom server parameters (Tom Lane)

    Non-superusers can no longer issue ALTER ROLE/DATABASE SET for parameters that are not currently known to the server. This allows the server to correctly check that superuser-only parameters are only set by superusers. Previously, the SET would be allowed and then ignored at session start, making superuser-only custom parameters much less useful than they should be.

E.5.3.2. Queries

  • Perform SELECT FOR UPDATE/SHARE processing after applying LIMIT, so the number of rows returned is always predictable (Tom Lane)

    Previously, changes made by concurrent transactions could cause a SELECT FOR UPDATE to unexpectedly return fewer rows than specified by its LIMIT. FOR UPDATE in combination with ORDER BY can still produce surprising results, but that can be corrected by placing FOR UPDATE in a subquery.

  • Allow mixing of traditional and SQL-standard LIMIT/OFFSET syntax (Tom Lane)

  • Extend the supported frame options in window functions (Hitoshi Harada)

    Frames can now start with CURRENT ROW, and the ROWS n PRECEDING/FOLLOWING options are now supported.

  • Make SELECT INTO and CREATE TABLE AS return row counts to the client in their command tags (Boszormenyi Zoltan)

    This can save an entire round-trip to the client, allowing result counts and pagination to be calculated without an additional COUNT query.

E.5.3.2.1. Unicode Strings

  • Support Unicode surrogate pairs (dual 16-bit representation) in U& strings and identifiers (Peter Eisentraut)

  • Support Unicode escapes in E'...' strings (Marko Kreen)

E.5.3.3. Object Manipulation

  • Speed up CREATE DATABASE by deferring flushes to disk (Andres Freund, Greg Stark)

  • Allow comments on columns of tables, views, and composite types only, not other relation types such as indexes and TOAST tables (Tom Lane)

  • Allow the creation of enumerated types containing no values (Bruce Momjian)

  • Let values of columns having storage type MAIN remain on the main heap page unless the row cannot fit on a page (Kevin Grittner)

    Previously MAIN values were forced out to TOAST tables until the row size was less than one-quarter of the page size.

E.5.3.3.1. ALTER TABLE

  • Implement IF EXISTS for ALTER TABLE DROP COLUMN and ALTER TABLE DROP CONSTRAINT (Andres Freund)

  • Allow ALTER TABLE commands that rewrite tables to skip WAL logging (Itagaki Takahiro)

    Such operations either produce a new copy of the table or are rolled back, so WAL archiving can be skipped, unless running in continuous archiving mode. This reduces I/O overhead and improves performance.

  • Fix failure of ALTER TABLE table ADD COLUMN col serial when done by non-owner of table (Tom Lane)

E.5.3.3.2. CREATE TABLE

  • Add support for copying COMMENTS and STORAGE settings in CREATE TABLE ... LIKE commands (Itagaki Takahiro)

  • Add a shortcut for copying all properties in CREATE TABLE ... LIKE commands (Itagaki Takahiro)

  • Add the SQL-standard CREATE TABLE ... OF type command (Peter Eisentraut)

    This allows creation of a table that matches an existing composite type. Additional constraints and defaults can be specified in the command.

E.5.3.3.3. Constraints

  • Add deferrable unique constraints (Dean Rasheed)

    This allows mass updates, such as UPDATE tab SET col = col + 1, to work reliably on columns that have unique indexes or are marked as primary keys. If the constraint is specified as DEFERRABLE it will be checked at the end of the statement, rather than after each row is updated. The constraint check can also be deferred until the end of the current transaction, allowing such updates to be spread over multiple SQL commands.

  • Add exclusion constraints (Jeff Davis)

    Exclusion constraints generalize uniqueness constraints by allowing arbitrary comparison operators, not just equality. They are created with the CREATE TABLE CONSTRAINT ... EXCLUDE clause. The most common use of exclusion constraints is to specify that column entries must not overlap, rather than simply not be equal. This is useful for time periods and other ranges, as well as arrays. This feature enhances checking of data integrity for many calendaring, time-management, and scientific applications.

  • Improve uniqueness-constraint violation error messages to report the values causing the failure (Itagaki Takahiro)

    For example, a uniqueness constraint violation might now report Key (x)=(2) already exists.

E.5.3.3.4. Object Permissions

  • Add the ability to make mass permission changes across a whole schema using the new GRANT/REVOKE IN SCHEMA clause (Petr Jelinek)

    This simplifies management of object permissions and makes it easier to utilize database roles for application data security.

  • Add ALTER DEFAULT PRIVILEGES command to control privileges of objects created later (Petr Jelinek)

    This greatly simplifies the assignment of object privileges in a complex database application. Default privileges can be set for tables, views, sequences, and functions. Defaults may be assigned on a per-schema basis, or database-wide.

  • Add the ability to control large object (BLOB) permissions with GRANT/REVOKE (KaiGai Kohei)

    Formerly, any database user could read or modify any large object. Read and write permissions can now be granted and revoked per large object, and the ownership of large objects is tracked.

E.5.3.4. Utility Operations

  • Make LISTEN/NOTIFY store pending events in a memory queue, rather than in a system table (Joachim Wieland)

    This substantially improves performance, while retaining the existing features of transactional support and guaranteed delivery.

  • Allow NOTIFY to pass an optional "payload" string to listeners (Joachim Wieland)

    This greatly improves the usefulness of LISTEN/NOTIFY as a general-purpose event queue system.

  • Allow CLUSTER on all per-database system catalogs (Tom Lane)

    Shared catalogs still cannot be clustered.

E.5.3.4.1. COPY

  • Accept COPY ... CSV FORCE QUOTE * (Itagaki Takahiro)

    Now * can be used as shorthand for "all columns" in the FORCE QUOTE clause.

  • Add new COPY syntax that allows options to be specified inside parentheses (Robert Haas, Emmanuel Cecchet)

    This allows greater flexibility for future COPY options. The old syntax is still supported, but only for pre-existing options.

E.5.3.4.2. EXPLAIN

  • Allow EXPLAIN to output in XML, JSON, or YAML format (Robert Haas, Greg Sabino Mullane)

    The new output formats are easily machine-readable, supporting the development of new tools for analysis of EXPLAIN output.

  • Add new BUFFERS option to report query buffer usage during EXPLAIN ANALYZE (Itagaki Takahiro)

    This allows better query profiling for individual queries. Buffer usage is no longer reported in the output for log_statement_stats and related settings.

  • Add hash usage information to EXPLAIN output (Robert Haas)

  • Add new EXPLAIN syntax that allows options to be specified inside parentheses (Robert Haas)

    This allows greater flexibility for future EXPLAIN options. The old syntax is still supported, but only for pre-existing options.

E.5.3.4.3. VACUUM

  • Change VACUUM FULL to rewrite the entire table and rebuild its indexes, rather than moving individual rows around to compact space (Itagaki Takahiro, Tom Lane)

    The previous method was usually slower and caused index bloat. Note that the new method will use more disk space transiently during VACUUM FULL; potentially as much as twice the space normally occupied by the table and its indexes.

  • Add new VACUUM syntax that allows options to be specified inside parentheses (Itagaki Takahiro)

    This allows greater flexibility for future VACUUM options. The old syntax is still supported, but only for pre-existing options.

E.5.3.4.4. Indexes

  • Allow an index to be named automatically by omitting the index name in CREATE INDEX (Tom Lane)

  • By default, multicolumn indexes are now named after all their columns; and index expression columns are now named based on their expressions (Tom Lane)

  • Reindexing shared system catalogs is now fully transactional and crash-safe (Tom Lane)

    Formerly, reindexing a shared index was only allowed in standalone mode, and a crash during the operation could leave the index in worse condition than it was before.

  • Add point_ops operator class for GiST (Teodor Sigaev)

    This feature permits GiST indexing of point columns. The index can be used for several types of queries such as point <@ polygon (point is in polygon). This should make many PostGIS queries faster.

  • Use red-black binary trees for GIN index creation (Teodor Sigaev)

    Red-black trees are self-balancing. This avoids slowdowns in cases where the input is in nonrandom order.

E.5.3.5. Data Types

  • Allow bytea values to be written in hex notation (Peter Eisentraut)

    The server parameter bytea_output controls whether hex or traditional format is used for bytea output. Libpq's PQescapeByteaConn() function automatically uses the hex format when connected to PostgreSQL 9.0 or newer servers. However, pre-9.0 libpq versions will not correctly process hex format from newer servers.

    The new hex format will be directly compatible with more applications that use binary data, allowing them to store and retrieve it without extra conversion. It is also significantly faster to read and write than the traditional format.

  • Allow server parameter extra_float_digits to be increased to 3 (Tom Lane)

    The previous maximum extra_float_digits setting was 2. There are cases where 3 digits are needed to dump and restore float4 values exactly. pg_dump will now use the setting of 3 when dumping from a server that allows it.

  • Tighten input checking for int2vector values (Caleb Welton)

E.5.3.5.1. Full Text Search

  • Add prefix support in synonym dictionaries (Teodor Sigaev)

  • Add filtering dictionaries (Teodor Sigaev)

    Filtering dictionaries allow tokens to be modified then passed to subsequent dictionaries.

  • Allow underscores in email-address tokens (Teodor Sigaev)

  • Use more standards-compliant rules for parsing URL tokens (Tom Lane)

E.5.3.6. Functions

  • Allow function calls to supply parameter names and match them to named parameters in the function definition (Pavel Stehule)

    For example, if a function is defined to take parameters a and b, it can be called with func(a := 7, b := 12) or func(b := 12, a := 7).

  • Support locale-specific regular expression processing with UTF-8 server encoding (Tom Lane)

    Locale-specific regular expression functionality includes case-insensitive matching and locale-specific character classes. Previously, these features worked correctly for non-ASCII characters only if the database used a single-byte server encoding (such as LATIN1). They will still misbehave in multi-byte encodings other than UTF-8.

  • Add support for scientific notation in to_char() ( EEEE specification) (Pavel Stehule, Brendan Jurd)

  • Make to_char() honor FM (fill mode) in Y, YY, and YYY specifications (Bruce Momjian, Tom Lane)

    It was already honored by YYYY.

  • Fix to_char() to output localized numeric and monetary strings in the correct encoding on Windows (Hiroshi Inoue, Itagaki Takahiro, Bruce Momjian)

  • Correct calculations of "overlaps" and "contains" operations for polygons (Teodor Sigaev)

    The polygon && (overlaps) operator formerly just checked to see if the two polygons' bounding boxes overlapped. It now does a more correct check. The polygon @> and <@ (contains/contained by) operators formerly checked to see if one polygon's vertexes were all contained in the other; this can wrongly report "true" for some non-convex polygons. Now they check that all line segments of one polygon are contained in the other.

E.5.3.6.1. Aggregates

  • Allow aggregate functions to use ORDER BY (Andrew Gierth)

    For example, this is now supported: array_agg(a ORDER BY b). This is useful with aggregates for which the order of input values is significant, and eliminates the need to use a nonstandard subquery to determine the ordering.

  • Multi-argument aggregate functions can now use DISTINCT (Andrew Gierth)

  • Add the string_agg() aggregate function to combine values into a single string (Pavel Stehule)

  • Aggregate functions that are called with DISTINCT are now passed NULL values if the aggregate transition function is not marked as STRICT (Andrew Gierth)

    For example, agg(DISTINCT x) might pass a NULL x value to agg(). This is more consistent with the behavior in non-DISTINCT cases.

E.5.3.6.2. Bit Strings

  • Add get_bit() and set_bit() functions for bit strings, mirroring those for bytea (Leonardo F)

  • Implement OVERLAY() (replace) for bit strings and bytea (Leonardo F)

E.5.3.6.3. Object Information Functions

  • Add pg_table_size() and pg_indexes_size() to provide a more user-friendly interface to the pg_relation_size() function (Bernd Helmle)

  • Add has_sequence_privilege() for sequence permission checking (Abhijit Menon-Sen)

  • Update the information_schema views to conform to SQL:2008 (Peter Eisentraut)

  • Make the information_schema views correctly display maximum octet lengths for char and varchar columns (Peter Eisentraut)

  • Speed up information_schema privilege views (Joachim Wieland)

E.5.3.6.4. Function and Trigger Creation

  • Support execution of anonymous code blocks using the DO statement (Petr Jelinek, Joshua Tolley, Hannu Valtonen)

    This allows execution of server-side code without the need to create and delete a temporary function definition. Code can be executed in any language for which the user has permissions to define a function.

  • Implement SQL-standard-compliant per-column triggers (Itagaki Takahiro)

    Such triggers are fired only when the specified column(s) are affected by the query, e.g. appear in an UPDATE's SET list.

  • Add the WHEN clause to CREATE TRIGGER to allow control over whether a trigger is fired (Itagaki Takahiro)

    While the same type of check can always be performed inside the trigger, doing it in an external WHEN clause can have performance benefits.

E.5.3.7. Server-Side Languages

  • Add the OR REPLACE clause to CREATE LANGUAGE (Tom Lane)

    This is helpful to optionally install a language if it does not already exist, and is particularly helpful now that PL/pgSQL is installed by default.

E.5.3.7.1. PL/pgSQL Server-Side Language

  • Install PL/pgSQL by default (Bruce Momjian)

    The language can still be removed from a particular database if the administrator has security or performance concerns about making it available.

  • Improve handling of cases where PL/pgSQL variable names conflict with identifiers used in queries within a function (Tom Lane)

    The default behavior is now to throw an error when there is a conflict, so as to avoid surprising behaviors. This can be modified, via the configuration parameter plpgsql.variable_conflict or the per-function option #variable_conflict, to allow either the variable or the query-supplied column to be used. In any case PL/pgSQL will no longer attempt to substitute variables in places where they would not be syntactically valid.

  • Make PL/pgSQL use the main lexer, rather than its own version (Tom Lane)

    This ensures accurate tracking of the main system's behavior for details such as string escaping. Some user-visible details, such as the set of keywords considered reserved in PL/pgSQL, have changed in consequence.

  • Avoid throwing an unnecessary error for an invalid record reference (Tom Lane)

    An error is now thrown only if the reference is actually fetched, rather than whenever the enclosing expression is reached. For example, many people have tried to do this in triggers:

    if TG_OP = 'INSERT' and NEW.col1 = ... then

    This will now actually work as expected.

  • Improve PL/pgSQL's ability to handle row types with dropped columns (Pavel Stehule)

  • Allow input parameters to be assigned values within PL/pgSQL functions (Steve Prentice)

    Formerly, input parameters were treated as being declared CONST, so the function's code could not change their values. This restriction has been removed to simplify porting of functions from other DBMSes that do not impose the equivalent restriction. An input parameter now acts like a local variable initialized to the passed-in value.

  • Improve error location reporting in PL/pgSQL (Tom Lane)

  • Add count and ALL options to MOVE FORWARD/BACKWARD in PL/pgSQL (Pavel Stehule)

  • Allow PL/pgSQL's WHERE CURRENT OF to use a cursor variable (Tom Lane)

  • Allow PL/pgSQL's OPEN cursor FOR EXECUTE to use parameters (Pavel Stehule, Itagaki Takahiro)

    This is accomplished with a new USING clause.

E.5.3.7.2. PL/Perl Server-Side Language

  • Add new PL/Perl functions: quote_literal(), quote_nullable(), quote_ident(), encode_bytea(), decode_bytea(), looks_like_number(), encode_array_literal(), encode_array_constructor() (Tim Bunce)

  • Add server parameter plperl.on_init to specify a PL/Perl initialization function (Tim Bunce)

    plperl.on_plperl_init and plperl.on_plperlu_init are also available for initialization that is specific to the trusted or untrusted language respectively.

  • Support END blocks in PL/Perl (Tim Bunce)

    END blocks do not currently allow database access.

  • Allow use strict in PL/Perl (Tim Bunce)

    Perl strict checks can also be globally enabled with the new server parameter plperl.use_strict.

  • Allow require in PL/Perl (Tim Bunce)

    This basically tests to see if the module is loaded, and if not, generates an error. It will not allow loading of modules that the administrator has not preloaded via the initialization parameters.

  • Allow use feature in PL/Perl if Perl version 5.10 or later is used (Tim Bunce)

  • Verify that PL/Perl return values are valid in the server encoding (Andrew Dunstan)

E.5.3.7.3. PL/Python Server-Side Language

  • Add Unicode support in PL/Python (Peter Eisentraut)

    Strings are automatically converted from/to the server encoding as necessary.

  • Improve bytea support in PL/Python (Caleb Welton)

    Bytea values passed into PL/Python are now represented as binary, rather than the PostgreSQL bytea text format. Bytea values containing null bytes are now also output properly from PL/Python. Passing of boolean, integer, and float values was also improved.

  • Support arrays as parameters and return values in PL/Python (Peter Eisentraut)

  • Improve mapping of SQL domains to Python types (Peter Eisentraut)

  • Add Python 3 support to PL/Python (Peter Eisentraut)

    The new server-side language is called plpython3u. This cannot be used in the same session with the Python 2 server-side language.

  • Improve error location and exception reporting in PL/Python (Peter Eisentraut)

E.5.3.8. Client Applications

  • Add an --analyze-only option to vacuumdb, to analyze without vacuuming (Bruce Momjian)

E.5.3.8.1. psql

  • Add support for quoting/escaping the values of psql variables as SQL strings or identifiers (Pavel Stehule, Robert Haas)

    For example, :'var' will produce the value of var quoted and properly escaped as a literal string, while :"var" will produce its value quoted and escaped as an identifier.

  • Ignore a leading UTF-8-encoded Unicode byte-order marker in script files read by psql (Itagaki Takahiro)

    This is enabled when the client encoding is UTF-8. It improves compatibility with certain editors, mostly on Windows, that insist on inserting such markers.

  • Fix psql --file - to properly honor --single-transaction (Bruce Momjian)

  • Avoid overwriting of psql's command-line history when two psql sessions are run concurrently (Tom Lane)

  • Improve psql's tab completion support (Itagaki Takahiro)

  • Show \timing output when it is enabled, regardless of "quiet" mode (Peter Eisentraut)

E.5.3.8.1.1. psql Display

  • Improve display of wrapped columns in psql (Roger Leigh)

    This behavior is now the default. The previous formatting is available by using \pset linestyle old-ascii.

  • Allow psql to use fancy Unicode line-drawing characters via \pset linestyle unicode (Roger Leigh)

E.5.3.8.1.2. psql \d Commands

  • Make \d show child tables that inherit from the specified parent (Damien Clochard)

    \d shows only the number of child tables, while \d+ shows the names of all child tables.

  • Show definitions of index columns in \d index_name (Khee Chin)

    The definition is useful for expression indexes.

  • Show a view's defining query only in \d+, not in \d (Peter Eisentraut)

    Always including the query was deemed overly verbose.

E.5.3.8.2. pg_dump

  • Make pg_dump/pg_restore --clean also remove large objects (Itagaki Takahiro)

  • Fix pg_dump to properly dump large objects when standard_conforming_strings is enabled (Tom Lane)

    The previous coding could fail when dumping to an archive file and then generating script output from pg_restore.

  • pg_restore now emits large-object data in hex format when generating script output (Tom Lane)

    This could cause compatibility problems if the script is then loaded into a pre-9.0 server. To work around that, restore directly to the server, instead.

  • Allow pg_dump to dump comments attached to columns of composite types (Taro Minowa (Higepon))

  • Make pg_dump --verbose output the pg_dump and server versions in text output mode (Jim Cox, Tom Lane)

    These were already provided in custom output mode.

  • pg_restore now complains if any command-line arguments remain after the switches and optional file name (Tom Lane)

    Previously, it silently ignored any such arguments.

E.5.3.8.3. pg_ctl

  • Allow pg_ctl to be used safely to start the postmaster during a system reboot (Tom Lane)

    Previously, pg_ctl's parent process could have been mistakenly identified as a running postmaster based on a stale postmaster lock file, resulting in a transient failure to start the database.

  • Give pg_ctl the ability to initialize the database (by invoking initdb) (Zdenek Kotala)

E.5.3.9. Development Tools

E.5.3.9.1. libpq

  • Add new libpq functions PQconnectdbParams() and PQconnectStartParams() (Guillaume Lelarge)

    These functions are similar to PQconnectdb() and PQconnectStart() except that they accept a null-terminated array of connection options, rather than requiring all options to be provided in a single string.

  • Add libpq functions PQescapeLiteral() and PQescapeIdentifier() (Robert Haas)

    These functions return appropriately quoted and escaped SQL string literals and identifiers. The caller is not required to pre-allocate the string result, as is required by PQescapeStringConn().

  • Add support for a per-user service file (.pg_service.conf), which is checked before the site-wide service file (Peter Eisentraut)

  • Properly report an error if the specified libpq service cannot be found (Peter Eisentraut)

  • Add TCP keepalive settings in libpq (Tollef Fog Heen, Fujii Masao, Robert Haas)

    Keepalive settings were already supported on the server end of TCP connections.

  • Avoid extra system calls to block and unblock SIGPIPE in libpq, on platforms that offer alternative methods (Jeremy Kerr)

  • When a .pgpass-supplied password fails, mention where the password came from in the error message (Bruce Momjian)

  • Load all SSL certificates given in the client certificate file (Tom Lane)

    This improves support for indirectly-signed SSL certificates.

E.5.3.9.2. ecpg

  • Add SQLDA (SQL Descriptor Area) support to ecpg (Boszormenyi Zoltan)

  • Add the DESCRIBE [ OUTPUT ] statement to ecpg (Boszormenyi Zoltan)

  • Add an ECPGtransactionStatus function to return the current transaction status (Bernd Helmle)

  • Add the string data type in ecpg Informix-compatibility mode (Boszormenyi Zoltan)

  • Allow ecpg to use new and old variable names without restriction (Michael Meskes)

  • Allow ecpg to use variable names in free() (Michael Meskes)

  • Make ecpg_dynamic_type() return zero for non-SQL3 data types (Michael Meskes)

    Previously it returned the negative of the data type OID. This could be confused with valid type OIDs, however.

  • Support long long types on platforms that already have 64-bit long (Michael Meskes)

E.5.3.9.2.1. ecpg Cursors

  • Add out-of-scope cursor support in ecpg's native mode (Boszormenyi Zoltan)

    This allows DECLARE to use variables that are not in scope when OPEN is called. This facility already existed in ecpg's Informix-compatibility mode.

  • Allow dynamic cursor names in ecpg (Boszormenyi Zoltan)

  • Allow ecpg to use noise words FROM and IN in FETCH and MOVE (Boszormenyi Zoltan)

E.5.3.10. Build Options

  • Enable client thread safety by default (Bruce Momjian)

    The thread-safety option can be disabled with configure --disable-thread-safety.

  • Add support for controlling the Linux out-of-memory killer (Alex Hunsaker, Tom Lane)

    Now that /proc/self/oom_adj allows disabling of the Linux out-of-memory (OOM) killer, it's recommendable to disable OOM kills for the postmaster. It may then be desirable to re-enable OOM kills for the postmaster's child processes. The new compile-time option LINUX_OOM_ADJ allows the killer to be reactivated for child processes.

E.5.3.10.1. Makefiles

  • New Makefile targets world, install-world, and installcheck-world (Andrew Dunstan)

    These are similar to the existing all, install, and installcheck targets, but they also build the HTML documentation, build and test contrib, and test server-side languages and ecpg.

  • Add data and documentation installation location control to PGXS Makefiles (Mark Cave-Ayland)

  • Add Makefile rules to build the PostgreSQL documentation as a single HTML file or as a single plain-text file (Peter Eisentraut, Bruce Momjian)

E.5.3.10.2. Windows

  • Support compiling on 64-bit Windows and running in 64-bit mode (Tsutomu Yamada, Magnus Hagander)

    This allows for large shared memory sizes on Windows.

  • Support server builds using Visual Studio 2008 (Magnus Hagander)

E.5.3.11. Source Code

  • Distribute prebuilt documentation in a subdirectory tree, rather than as tar archive files inside the distribution tarball (Peter Eisentraut)

    For example, the prebuilt HTML documentation is now in doc/src/sgml/html/; the manual pages are packaged similarly.

  • Make the server's lexer reentrant (Tom Lane)

    This was needed for use of the lexer by PL/pgSQL.

  • Improve speed of memory allocation (Tom Lane, Greg Stark)

  • User-defined constraint triggers now have entries in pg_constraint as well as pg_trigger (Tom Lane)

    Because of this change, pg_constraint.pgconstrname is now redundant and has been removed.

  • Add system catalog columns pg_constraint.conindid and pg_trigger.tgconstrindid to better document the use of indexes for constraint enforcement (Tom Lane)

  • Allow multiple conditions to be communicated to backends using a single operating system signal (Fujii Masao)

    This allows new features to be added without a platform-specific constraint on the number of signal conditions.

  • Improve source code test coverage, including contrib, PL/Python, and PL/Perl (Peter Eisentraut, Andrew Dunstan)

  • Remove the use of flat files for system table bootstrapping (Tom Lane, Alvaro Herrera)

    This improves performance when using many roles or databases, and eliminates some possible failure conditions.

  • Automatically generate the initial contents of pg_attribute for "bootstrapped" catalogs (John Naylor)

    This greatly simplifies changes to these catalogs.

  • Split the processing of INSERT/UPDATE/DELETE operations out of execMain.c (Marko Tiikkaja)

    Updates are now executed in a separate ModifyTable node. This change is necessary infrastructure for future improvements.

  • Simplify translation of psql's SQL help text (Peter Eisentraut)

  • Reduce the lengths of some file names so that all file paths in the distribution tarball are less than 100 characters (Tom Lane)

    Some decompression programs have problems with longer file paths.

  • Add a new ERRCODE_INVALID_PASSWORD SQLSTATE error code (Bruce Momjian)

  • With authors' permissions, remove the few remaining personal source code copyright notices (Bruce Momjian)

    The personal copyright notices were insignificant but the community occasionally had to answer questions about them.

  • Add new documentation section about running PostgreSQL in non-durable mode to improve performance (Bruce Momjian)

  • Restructure the HTML documentation Makefile rules to make their dependency checks work correctly, avoiding unnecessary rebuilds (Peter Eisentraut)

  • Use DocBook XSL stylesheets for man page building, rather than Docbook2X (Peter Eisentraut)

    This changes the set of tools needed to build the man pages.

  • Improve PL/Perl code structure (Tim Bunce)

  • Improve error context reports in PL/Perl (Alexey Klyukin)

E.5.3.11.1. New Build Requirements

Note that these requirements do not apply when building from a distribution tarball, since tarballs include the files that these programs are used to build.

  • Require Autoconf 2.63 to build configure (Peter Eisentraut)

  • Require Flex 2.5.31 or later to build from a CVS checkout (Tom Lane)

  • Require Perl version 5.8 or later to build from a CVS checkout (John Naylor, Andrew Dunstan)

E.5.3.11.2. Portability

  • Use a more modern API for Bonjour (Tom Lane)

    Bonjour support now requires OS X 10.3 or later. The older API has been deprecated by Apple.

  • Add spinlock support for the SuperH architecture (Nobuhiro Iwamatsu)

  • Allow non-GCC compilers to use inline functions if they support them (Kurt Harriman)

  • Remove support for platforms that don't have a working 64-bit integer data type (Tom Lane)

  • Restructure use of LDFLAGS to be more consistent across platforms (Tom Lane)

    LDFLAGS is now used for linking both executables and shared libraries, and we add on LDFLAGS_EX when linking executables, or LDFLAGS_SL when linking shared libraries.

E.5.3.11.3. Server Programming

  • Make backend header files safe to include in C++ (Kurt Harriman, Peter Eisentraut)

    These changes remove keyword conflicts that previously made C++ usage difficult in backend code. However, there are still other complexities when using C++ for backend functions. extern "C" { } is still necessary in appropriate places, and memory management and error handling are still problematic.

  • Add AggCheckCallContext() for use in detecting if a C function is being called as an aggregate (Hitoshi Harada)

  • Change calling convention for SearchSysCache() and related functions to avoid hard-wiring the maximum number of cache keys (Robert Haas)

    Existing calls will still work for the moment, but can be expected to break in 9.1 or later if not converted to the new style.

  • Require calls of fastgetattr() and heap_getattr() backend macros to provide a non-NULL fourth argument (Robert Haas)

  • Custom typanalyze functions should no longer rely on VacAttrStats.attr to determine the type of data they will be passed (Tom Lane)

    This was changed to allow collection of statistics on index columns for which the storage type is different from the underlying column data type. There are new fields that tell the actual datatype being analyzed.

E.5.3.11.4. Server Hooks

  • Add parser hooks for processing ColumnRef and ParamRef nodes (Tom Lane)

  • Add a ProcessUtility hook so loadable modules can control utility commands (Itagaki Takahiro)

E.5.3.11.5. Binary Upgrade Support

  • Add contrib/pg_upgrade to support in-place upgrades (Bruce Momjian)

    This avoids the requirement of dumping/reloading the database when upgrading to a new major release of PostgreSQL, thus reducing downtime by orders of magnitude. It supports upgrades to 9.0 from PostgreSQL 8.3 and 8.4.

  • Add support for preserving relation relfilenode values during binary upgrades (Bruce Momjian)

  • Add support for preserving pg_type and pg_enum OIDs during binary upgrades (Bruce Momjian)

  • Move data files within tablespaces into PostgreSQL-version-specific subdirectories (Bruce Momjian)

    This simplifies binary upgrades.

E.5.3.12. Contrib

  • Add multithreading option (-j) to contrib/pgbench (Itagaki Takahiro)

    This allows multiple CPUs to be used by pgbench, reducing the risk of pgbench itself becoming the test bottleneck.

  • Add \shell and \setshell meta commands to contrib/pgbench (Michael Paquier)

  • New features for contrib/dict_xsyn (Sergey Karpov)

    The new options are matchorig, matchsynonyms, and keepsynonyms.

  • Add full text dictionary contrib/unaccent (Teodor Sigaev)

    This filtering dictionary removes accents from letters, which makes full-text searches over multiple languages much easier.

  • Add dblink_get_notify() to contrib/dblink (Marcus Kempe)

    This allows asynchronous notifications in dblink.

  • Improve contrib/dblink's handling of dropped columns (Tom Lane)

    This affects dblink_build_sql_insert() and related functions. These functions now number columns according to logical not physical column numbers.

  • Greatly increase contrib/hstore's data length limit, and add B-tree and hash support so GROUP BY and DISTINCT operations are possible on hstore columns (Andrew Gierth)

    New functions and operators were also added. These improvements make hstore a full-function key-value store embedded in PostgreSQL.

  • Add contrib/passwordcheck to support site-specific password strength policies (Laurenz Albe)

    The source code of this module should be modified to implement site-specific password policies.

  • Add contrib/pg_archivecleanup tool (Simon Riggs)

    This is designed to be used in the archive_cleanup_command server parameter, to remove no-longer-needed archive files.

  • Add query text to contrib/auto_explain output (Andrew Dunstan)

  • Add buffer access counters to contrib/pg_stat_statements (Itagaki Takahiro)

  • Update contrib/start-scripts/linux to use /proc/self/oom_adj to disable the Linux out-of-memory (OOM) killer (Alex Hunsaker, Tom Lane)

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