The PostgreSQL Global Development Group · 8.5. Date/Time Types.....126 8.5.1. Date/Time...

PostgreSQL 9.6.0 Documentation

The PostgreSQL Global Development Group

PostgreSQL 9.6.0 Documentationby The PostgreSQL Global Development GroupCopyright © 1996-2016 The PostgreSQL Global Development Group

Legal Notice

PostgreSQL is Copyright © 1996-2016 by the PostgreSQL Global Development Group.

Postgres95 is Copyright © 1994-5 by the Regents of the University of California.

Permission to use, copy, modify, and distribute this software and its documentation for any purpose, without fee, and without a writtenagreement is hereby granted, provided that the above copyright notice and this paragraph and the following two paragraphs appear in allcopies.

IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL,INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWAREAND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OFSUCH DAMAGE.

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Table of ContentsPreface ...........................................................................................................................................lxviii

1. What is PostgreSQL? ........................................................................................................lxviii2. A Brief History of PostgreSQL...........................................................................................lxix

2.1. The Berkeley POSTGRES Project .........................................................................lxix2.2. Postgres95...............................................................................................................lxix2.3. PostgreSQL.............................................................................................................. lxx

3. Conventions.......................................................................................................................... lxx4. Further Information.............................................................................................................lxxi5. Bug Reporting Guidelines...................................................................................................lxxi

5.1. Identifying Bugs ....................................................................................................lxxii5.2. What to Report ......................................................................................................lxxii5.3. Where to Report Bugs .......................................................................................... lxxiv

I. Tutorial ............................................................................................................................................. 11. Getting Started ........................................................................................................................ 1

1.1. Installation .................................................................................................................. 11.2. Architectural Fundamentals........................................................................................ 11.3. Creating a Database.................................................................................................... 21.4. Accessing a Database ................................................................................................. 3

2. The SQL Language ................................................................................................................. 52.1. Introduction ................................................................................................................ 52.2. Concepts ..................................................................................................................... 52.3. Creating a New Table ................................................................................................. 52.4. Populating a Table With Rows ................................................................................... 62.5. Querying a Table ........................................................................................................ 72.6. Joins Between Tables.................................................................................................. 92.7. Aggregate Functions................................................................................................. 112.8. Updates ..................................................................................................................... 122.9. Deletions................................................................................................................... 13

3. Advanced Features ................................................................................................................ 143.1. Introduction .............................................................................................................. 143.2. Views ........................................................................................................................ 143.3. Foreign Keys............................................................................................................. 143.4. Transactions.............................................................................................................. 153.5. Window Functions.................................................................................................... 173.6. Inheritance ................................................................................................................ 203.7. Conclusion................................................................................................................ 21

II. The SQL Language...................................................................................................................... 224. SQL Syntax ........................................................................................................................... 24

4.1. Lexical Structure....................................................................................................... 244.1.1. Identifiers and Key Words............................................................................ 244.1.2. Constants...................................................................................................... 26

4.1.2.1. String Constants .............................................................................. 264.1.2.2. String Constants with C-style Escapes............................................ 264.1.2.3. String Constants with Unicode Escapes.......................................... 284.1.2.4. Dollar-quoted String Constants ....................................................... 284.1.2.5. Bit-string Constants......................................................................... 294.1.2.6. Numeric Constants .......................................................................... 294.1.2.7. Constants of Other Types ................................................................ 30

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4.1.3. Operators...................................................................................................... 314.1.4. Special Characters........................................................................................ 314.1.5. Comments .................................................................................................... 324.1.6. Operator Precedence .................................................................................... 32

4.2. Value Expressions..................................................................................................... 334.2.1. Column References...................................................................................... 344.2.2. Positional Parameters................................................................................... 344.2.3. Subscripts..................................................................................................... 354.2.4. Field Selection ............................................................................................. 354.2.5. Operator Invocations.................................................................................... 364.2.6. Function Calls .............................................................................................. 364.2.7. Aggregate Expressions................................................................................. 374.2.8. Window Function Calls................................................................................ 394.2.9. Type Casts .................................................................................................... 414.2.10. Collation Expressions ................................................................................ 414.2.11. Scalar Subqueries....................................................................................... 424.2.12. Array Constructors..................................................................................... 424.2.13. Row Constructors....................................................................................... 444.2.14. Expression Evaluation Rules ..................................................................... 45

4.3. Calling Functions...................................................................................................... 474.3.1. Using Positional Notation ............................................................................ 474.3.2. Using Named Notation ................................................................................ 484.3.3. Using Mixed Notation.................................................................................. 48

5. Data Definition ...................................................................................................................... 505.1. Table Basics.............................................................................................................. 505.2. Default Values .......................................................................................................... 515.3. Constraints ................................................................................................................ 52

5.3.1. Check Constraints ........................................................................................ 525.3.2. Not-Null Constraints.................................................................................... 545.3.3. Unique Constraints....................................................................................... 555.3.4. Primary Keys................................................................................................ 565.3.5. Foreign Keys ................................................................................................ 565.3.6. Exclusion Constraints .................................................................................. 59

5.4. System Columns....................................................................................................... 595.5. Modifying Tables...................................................................................................... 61

5.5.1. Adding a Column......................................................................................... 615.5.2. Removing a Column .................................................................................... 625.5.3. Adding a Constraint ..................................................................................... 625.5.4. Removing a Constraint ................................................................................ 625.5.5. Changing a Column’s Default Value............................................................ 635.5.6. Changing a Column’s Data Type ................................................................. 635.5.7. Renaming a Column .................................................................................... 635.5.8. Renaming a Table ........................................................................................ 63

5.6. Privileges .................................................................................................................. 645.7. Row Security Policies............................................................................................... 645.8. Schemas.................................................................................................................... 69

5.8.1. Creating a Schema ....................................................................................... 705.8.2. The Public Schema ...................................................................................... 715.8.3. The Schema Search Path.............................................................................. 715.8.4. Schemas and Privileges................................................................................ 725.8.5. The System Catalog Schema ....................................................................... 725.8.6. Usage Patterns.............................................................................................. 73

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5.8.7. Portability..................................................................................................... 735.9. Inheritance ................................................................................................................ 74

5.9.1. Caveats ......................................................................................................... 775.10. Partitioning ............................................................................................................. 77

5.10.1. Overview.................................................................................................... 775.10.2. Implementing Partitioning ......................................................................... 785.10.3. Managing Partitions ................................................................................... 815.10.4. Partitioning and Constraint Exclusion ....................................................... 825.10.5. Alternative Partitioning Methods............................................................... 835.10.6. Caveats ....................................................................................................... 84

5.11. Foreign Data ........................................................................................................... 845.12. Other Database Objects .......................................................................................... 855.13. Dependency Tracking............................................................................................. 85

6. Data Manipulation................................................................................................................. 876.1. Inserting Data ........................................................................................................... 876.2. Updating Data........................................................................................................... 886.3. Deleting Data............................................................................................................ 89

7. Queries .................................................................................................................................. 907.1. Overview .................................................................................................................. 907.2. Table Expressions ..................................................................................................... 90

7.2.1. The FROM Clause.......................................................................................... 917.2.1.1. Joined Tables ................................................................................... 917.2.1.2. Table and Column Aliases............................................................... 957.2.1.3. Subqueries ....................................................................................... 967.2.1.4. Table Functions ............................................................................... 967.2.1.5. LATERAL Subqueries ....................................................................... 98

7.2.2. The WHERE Clause........................................................................................ 997.2.3. The GROUP BY and HAVING Clauses......................................................... 1007.2.4. GROUPING SETS, CUBE, and ROLLUP ....................................................... 1027.2.5. Window Function Processing .................................................................... 104

7.3. Select Lists.............................................................................................................. 1047.3.1. Select-List Items ........................................................................................ 1057.3.2. Column Labels ........................................................................................... 1057.3.3. DISTINCT .................................................................................................. 106

7.4. Combining Queries................................................................................................. 1067.5. Sorting Rows .......................................................................................................... 1077.6. LIMIT and OFFSET................................................................................................. 1087.7. VALUES Lists .......................................................................................................... 1087.8. WITH Queries (Common Table Expressions) ......................................................... 109

7.8.1. SELECT in WITH......................................................................................... 1097.8.2. Data-Modifying Statements in WITH ......................................................... 113

8. Data Types........................................................................................................................... 1158.1. Numeric Types........................................................................................................ 116

8.1.1. Integer Types.............................................................................................. 1178.1.2. Arbitrary Precision Numbers ..................................................................... 1178.1.3. Floating-Point Types .................................................................................. 1198.1.4. Serial Types................................................................................................ 120

8.2. Monetary Types ...................................................................................................... 1218.3. Character Types ...................................................................................................... 1228.4. Binary Data Types .................................................................................................. 124

8.4.1. bytea Hex Format..................................................................................... 1248.4.2. bytea Escape Format................................................................................ 124

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8.5. Date/Time Types..................................................................................................... 1268.5.1. Date/Time Input ......................................................................................... 128

8.5.1.1. Dates.............................................................................................. 1288.5.1.2. Times ............................................................................................. 1298.5.1.3. Time Stamps.................................................................................. 1308.5.1.4. Special Values ............................................................................... 131

8.5.2. Date/Time Output ...................................................................................... 1318.5.3. Time Zones ................................................................................................ 1328.5.4. Interval Input.............................................................................................. 1348.5.5. Interval Output ........................................................................................... 136

8.6. Boolean Type.......................................................................................................... 1368.7. Enumerated Types .................................................................................................. 137

8.7.1. Declaration of Enumerated Types.............................................................. 1378.7.2. Ordering ..................................................................................................... 1388.7.3. Type Safety ................................................................................................ 1388.7.4. Implementation Details.............................................................................. 139

8.8. Geometric Types..................................................................................................... 1398.8.1. Points ......................................................................................................... 1408.8.2. Lines........................................................................................................... 1408.8.3. Line Segments............................................................................................ 1408.8.4. Boxes.......................................................................................................... 1418.8.5. Paths........................................................................................................... 1418.8.6. Polygons..................................................................................................... 1418.8.7. Circles ........................................................................................................ 142

8.9. Network Address Types.......................................................................................... 1428.9.1. inet ........................................................................................................... 1428.9.2. cidr ........................................................................................................... 1438.9.3. inet vs. cidr............................................................................................ 1438.9.4. macaddr .................................................................................................... 143

8.10. Bit String Types .................................................................................................... 1448.11. Text Search Types................................................................................................. 145

8.11.1. tsvector ................................................................................................ 1458.11.2. tsquery .................................................................................................. 146

8.12. UUID Type ........................................................................................................... 1478.13. XML Type ............................................................................................................ 148

8.13.1. Creating XML Values .............................................................................. 1488.13.2. Encoding Handling .................................................................................. 1498.13.3. Accessing XML Values............................................................................ 150

8.14. JSON Types .......................................................................................................... 1508.14.1. JSON Input and Output Syntax................................................................ 1528.14.2. Designing JSON documents effectively .................................................. 1538.14.3. jsonb Containment and Existence.......................................................... 1538.14.4. jsonb Indexing........................................................................................ 155

8.15. Arrays ................................................................................................................... 1578.15.1. Declaration of Array Types...................................................................... 1578.15.2. Array Value Input..................................................................................... 1588.15.3. Accessing Arrays ..................................................................................... 1598.15.4. Modifying Arrays..................................................................................... 1618.15.5. Searching in Arrays.................................................................................. 1648.15.6. Array Input and Output Syntax................................................................ 165

8.16. Composite Types .................................................................................................. 1668.16.1. Declaration of Composite Types.............................................................. 167

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8.16.2. Composite Value Input............................................................................. 1688.16.3. Accessing Composite Types .................................................................... 1688.16.4. Modifying Composite Types.................................................................... 1698.16.5. Composite Type Input and Output Syntax............................................... 169

8.17. Range Types ......................................................................................................... 1708.17.1. Built-in Range Types ............................................................................... 1718.17.2. Examples.................................................................................................. 1718.17.3. Inclusive and Exclusive Bounds .............................................................. 1718.17.4. Infinite (Unbounded) Ranges................................................................... 1728.17.5. Range Input/Output.................................................................................. 1728.17.6. Constructing Ranges ................................................................................ 1738.17.7. Discrete Range Types .............................................................................. 1738.17.8. Defining New Range Types ..................................................................... 1748.17.9. Indexing ................................................................................................... 1758.17.10. Constraints on Ranges............................................................................ 175

8.18. Object Identifier Types ......................................................................................... 1768.19. pg_lsn Type........................................................................................................... 1788.20. Pseudo-Types........................................................................................................ 178

9. Functions and Operators ..................................................................................................... 1809.1. Logical Operators ................................................................................................... 1809.2. Comparison Functions and Operators .................................................................... 1809.3. Mathematical Functions and Operators.................................................................. 1839.4. String Functions and Operators .............................................................................. 187

9.4.1. format....................................................................................................... 2029.5. Binary String Functions and Operators .................................................................. 2049.6. Bit String Functions and Operators ........................................................................ 2069.7. Pattern Matching .................................................................................................... 207

9.7.1. LIKE ........................................................................................................... 2079.7.2. SIMILAR TO Regular Expressions ............................................................ 2089.7.3. POSIX Regular Expressions ...................................................................... 209

9.7.3.1. Regular Expression Details ........................................................... 2139.7.3.2. Bracket Expressions ...................................................................... 2159.7.3.3. Regular Expression Escapes.......................................................... 2169.7.3.4. Regular Expression Metasyntax.................................................... 2189.7.3.5. Regular Expression Matching Rules ............................................. 2209.7.3.6. Limits and Compatibility .............................................................. 2219.7.3.7. Basic Regular Expressions ............................................................ 222

9.8. Data Type Formatting Functions ............................................................................ 2229.9. Date/Time Functions and Operators....................................................................... 229

9.9.1. EXTRACT, date_part ............................................................................... 2349.9.2. date_trunc .............................................................................................. 2389.9.3. AT TIME ZONE.......................................................................................... 2399.9.4. Current Date/Time ..................................................................................... 2399.9.5. Delaying Execution.................................................................................... 241

9.10. Enum Support Functions ...................................................................................... 2429.11. Geometric Functions and Operators ..................................................................... 2439.12. Network Address Functions and Operators.......................................................... 2479.13. Text Search Functions and Operators ................................................................... 2499.14. XML Functions .................................................................................................... 254

9.14.1. Producing XML Content.......................................................................... 2559.14.1.1. xmlcomment ............................................................................... 2559.14.1.2. xmlconcat ................................................................................. 255

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9.14.1.3. xmlelement ............................................................................... 2569.14.1.4. xmlforest ................................................................................. 2579.14.1.5. xmlpi .......................................................................................... 2589.14.1.6. xmlroot...................................................................................... 2589.14.1.7. xmlagg ........................................................................................ 258

9.14.2. XML Predicates ....................................................................................... 2599.14.2.1. IS DOCUMENT ............................................................................. 2599.14.2.2. XMLEXISTS ................................................................................. 2599.14.2.3. xml_is_well_formed .............................................................. 260

9.14.3. Processing XML ...................................................................................... 2619.14.4. Mapping Tables to XML.......................................................................... 262

9.15. JSON Functions and Operators ............................................................................ 2659.16. Sequence Manipulation Functions ....................................................................... 2749.17. Conditional Expressions....................................................................................... 277

9.17.1. CASE ......................................................................................................... 2779.17.2. COALESCE ................................................................................................ 2789.17.3. NULLIF..................................................................................................... 2799.17.4. GREATEST and LEAST.............................................................................. 279

9.18. Array Functions and Operators ............................................................................ 2799.19. Range Functions and Operators............................................................................ 2839.20. Aggregate Functions............................................................................................. 2859.21. Window Functions................................................................................................ 2949.22. Subquery Expressions .......................................................................................... 296

9.22.1. EXISTS..................................................................................................... 2969.22.2. IN ............................................................................................................. 2969.22.3. NOT IN..................................................................................................... 2979.22.4. ANY/SOME ................................................................................................. 2979.22.5. ALL ........................................................................................................... 2989.22.6. Single-row Comparison ........................................................................... 298

9.23. Row and Array Comparisons ............................................................................... 2999.23.1. IN ............................................................................................................. 2999.23.2. NOT IN..................................................................................................... 2999.23.3. ANY/SOME (array) ..................................................................................... 3009.23.4. ALL (array) ............................................................................................... 3009.23.5. Row Constructor Comparison.................................................................. 3009.23.6. Composite Type Comparison................................................................... 301

9.24. Set Returning Functions ....................................................................................... 3029.25. System Information Functions ............................................................................. 3059.26. System Administration Functions ........................................................................ 320

9.26.1. Configuration Settings Functions............................................................. 3219.26.2. Server Signaling Functions ...................................................................... 3219.26.3. Backup Control Functions ....................................................................... 3229.26.4. Recovery Control Functions .................................................................... 3259.26.5. Snapshot Synchronization Functions....................................................... 3269.26.6. Replication Functions .............................................................................. 3279.26.7. Database Object Management Functions................................................. 3319.26.8. Index Maintenance Functions .................................................................. 3349.26.9. Generic File Access Functions................................................................. 3349.26.10. Advisory Lock Functions....................................................................... 335

9.27. Trigger Functions ................................................................................................. 3389.28. Event Trigger Functions ....................................................................................... 338

9.28.1. Capturing Changes at Command End...................................................... 338

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9.28.2. Processing Objects Dropped by a DDL Command ................................. 3399.28.3. Handling a Table Rewrite Event .............................................................. 340

10. Type Conversion................................................................................................................ 34210.1. Overview .............................................................................................................. 34210.2. Operators .............................................................................................................. 34310.3. Functions .............................................................................................................. 34710.4. Value Storage........................................................................................................ 35010.5. UNION, CASE, and Related Constructs.................................................................. 351

11. Indexes .............................................................................................................................. 35311.1. Introduction .......................................................................................................... 35311.2. Index Types........................................................................................................... 35411.3. Multicolumn Indexes............................................................................................ 35611.4. Indexes and ORDER BY......................................................................................... 35711.5. Combining Multiple Indexes ................................................................................ 35811.6. Unique Indexes ..................................................................................................... 35911.7. Indexes on Expressions ........................................................................................ 35911.8. Partial Indexes ...................................................................................................... 36011.9. Operator Classes and Operator Families .............................................................. 36211.10. Indexes and Collations........................................................................................ 36411.11. Index-Only Scans ............................................................................................... 36411.12. Examining Index Usage...................................................................................... 366

12. Full Text Search ................................................................................................................ 36812.1. Introduction .......................................................................................................... 368

12.1.1. What Is a Document?............................................................................... 36912.1.2. Basic Text Matching ................................................................................ 36912.1.3. Configurations.......................................................................................... 371

12.2. Tables and Indexes................................................................................................ 37212.2.1. Searching a Table ..................................................................................... 37212.2.2. Creating Indexes ...................................................................................... 373

12.3. Controlling Text Search........................................................................................ 37412.3.1. Parsing Documents .................................................................................. 37412.3.2. Parsing Queries ........................................................................................ 37512.3.3. Ranking Search Results ........................................................................... 37712.3.4. Highlighting Results ................................................................................ 379

12.4. Additional Features .............................................................................................. 38012.4.1. Manipulating Documents......................................................................... 38012.4.2. Manipulating Queries............................................................................... 381

12.4.2.1. Query Rewriting .......................................................................... 38212.4.3. Triggers for Automatic Updates .............................................................. 38412.4.4. Gathering Document Statistics ................................................................ 385

12.5. Parsers................................................................................................................... 38612.6. Dictionaries........................................................................................................... 387

12.6.1. Stop Words............................................................................................... 38812.6.2. Simple Dictionary .................................................................................... 38912.6.3. Synonym Dictionary ................................................................................ 39012.6.4. Thesaurus Dictionary ............................................................................... 392

12.6.4.1. Thesaurus Configuration ............................................................. 39312.6.4.2. Thesaurus Example ..................................................................... 393

12.6.5. Ispell Dictionary....................................................................................... 39412.6.6. Snowball Dictionary ................................................................................ 397

12.7. Configuration Example......................................................................................... 39712.8. Testing and Debugging Text Search ..................................................................... 399

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12.8.1. Configuration Testing............................................................................... 39912.8.2. Parser Testing........................................................................................... 40112.8.3. Dictionary Testing.................................................................................... 402

12.9. GIN and GiST Index Types .................................................................................. 40312.10. psql Support........................................................................................................ 40312.11. Limitations.......................................................................................................... 40612.12. Migration from Pre-8.3 Text Search................................................................... 406

13. Concurrency Control ......................................................................................................... 40813.1. Introduction .......................................................................................................... 40813.2. Transaction Isolation ............................................................................................ 408

13.2.1. Read Committed Isolation Level ............................................................. 40913.2.2. Repeatable Read Isolation Level.............................................................. 41113.2.3. Serializable Isolation Level...................................................................... 412

13.3. Explicit Locking ................................................................................................... 41413.3.1. Table-level Locks ..................................................................................... 41413.3.2. Row-level Locks ...................................................................................... 41713.3.3. Page-level Locks ...................................................................................... 41813.3.4. Deadlocks................................................................................................. 41813.3.5. Advisory Locks........................................................................................ 419

13.4. Data Consistency Checks at the Application Level.............................................. 42013.4.1. Enforcing Consistency With Serializable Transactions ........................... 42013.4.2. Enforcing Consistency With Explicit Blocking Locks ............................ 421

13.5. Caveats.................................................................................................................. 42213.6. Locking and Indexes............................................................................................. 422

14. Performance Tips .............................................................................................................. 42414.1. Using EXPLAIN .................................................................................................... 424

14.1.1. EXPLAIN Basics ....................................................................................... 42414.1.2. EXPLAIN ANALYZE ................................................................................. 43014.1.3. Caveats ..................................................................................................... 433

14.2. Statistics Used by the Planner .............................................................................. 43414.3. Controlling the Planner with Explicit JOIN Clauses............................................ 43614.4. Populating a Database .......................................................................................... 438

14.4.1. Disable Autocommit ................................................................................ 43814.4.2. Use COPY.................................................................................................. 43814.4.3. Remove Indexes ....................................................................................... 43814.4.4. Remove Foreign Key Constraints ............................................................ 43914.4.5. Increase maintenance_work_mem ........................................................ 43914.4.6. Increase max_wal_size ......................................................................... 43914.4.7. Disable WAL Archival and Streaming Replication ................................. 43914.4.8. Run ANALYZE Afterwards........................................................................ 44014.4.9. Some Notes About pg_dump................................................................... 440

14.5. Non-Durable Settings ........................................................................................... 44115. Parallel Query.................................................................................................................... 442

15.1. How Parallel Query Works ................................................................................... 44215.2. When Can Parallel Query Be Used?..................................................................... 44315.3. Parallel Plans ........................................................................................................ 444

15.3.1. Parallel Scans ........................................................................................... 44415.3.2. Parallel Joins ............................................................................................ 44415.3.3. Parallel Aggregation ................................................................................ 44415.3.4. Parallel Plan Tips ..................................................................................... 445

15.4. Parallel Safety....................................................................................................... 44515.4.1. Parallel Labeling for Functions and Aggregates...................................... 445

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III. Server Administration ............................................................................................................. 44716. Installation from Source Code .......................................................................................... 449

16.1. Short Version ........................................................................................................ 44916.2. Requirements........................................................................................................ 44916.3. Getting The Source............................................................................................... 45116.4. Installation Procedure........................................................................................... 45116.5. Post-Installation Setup.......................................................................................... 461

16.5.1. Shared Libraries ....................................................................................... 46116.5.2. Environment Variables ............................................................................. 462

16.6. Supported Platforms ............................................................................................. 46316.7. Platform-specific Notes ........................................................................................ 463

16.7.1. AIX .......................................................................................................... 46316.7.1.1. GCC Issues.................................................................................. 46416.7.1.2. Unix-Domain Sockets Broken..................................................... 46416.7.1.3. Internet Address Issues................................................................ 46416.7.1.4. Memory Management ................................................................. 465

References and Resources ................................................................ 46616.7.2. Cygwin..................................................................................................... 46616.7.3. HP-UX ..................................................................................................... 46716.7.4. MinGW/Native Windows ........................................................................ 468

16.7.4.1. Collecting Crash Dumps on Windows ........................................ 46816.7.5. SCO OpenServer and SCO UnixWare..................................................... 468

16.7.5.1. Skunkware ................................................................................... 46916.7.5.2. GNU Make .................................................................................. 46916.7.5.3. Readline....................................................................................... 46916.7.5.4. Using the UDK on OpenServer................................................... 46916.7.5.5. Reading the PostgreSQL Man Pages........................................... 46916.7.5.6. C99 Issues with the 7.1.1b Feature Supplement ......................... 47016.7.5.7. Threading on UnixWare .............................................................. 470

16.7.6. Solaris ...................................................................................................... 47016.7.6.1. Required Tools ............................................................................ 47016.7.6.2. Problems with OpenSSL ............................................................. 47016.7.6.3. configure Complains About a Failed Test Program .................... 47116.7.6.4. 64-bit Build Sometimes Crashes ................................................. 47116.7.6.5. Compiling for Optimal Performance........................................... 47116.7.6.6. Using DTrace for Tracing PostgreSQL....................................... 471

17. Installation from Source Code on Windows ..................................................................... 47317.1. Building with Visual C++ or the Microsoft Windows SDK................................. 473

17.1.1. Requirements ........................................................................................... 47417.1.2. Special Considerations for 64-bit Windows ............................................ 47617.1.3. Building ................................................................................................... 47617.1.4. Cleaning and Installing ............................................................................ 47617.1.5. Running the Regression Tests .................................................................. 47717.1.6. Building the Documentation .................................................................... 477

17.2. Building libpq with Visual C++ or Borland C++................................................. 47817.2.1. Generated Files ........................................................................................ 478

18. Server Setup and Operation .............................................................................................. 48018.1. The PostgreSQL User Account ............................................................................ 48018.2. Creating a Database Cluster ................................................................................. 480

18.2.1. Use of Secondary File Systems................................................................ 48118.2.2. Use of Network File Systems .................................................................. 481

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18.3. Starting the Database Server................................................................................. 48218.3.1. Server Start-up Failures ........................................................................... 48418.3.2. Client Connection Problems .................................................................... 484

18.4. Managing Kernel Resources................................................................................. 48518.4.1. Shared Memory and Semaphores ............................................................ 48518.4.2. Resource Limits ....................................................................................... 49018.4.3. Linux Memory Overcommit .................................................................... 49118.4.4. Linux huge pages ..................................................................................... 493

18.5. Shutting Down the Server..................................................................................... 49318.6. Upgrading a PostgreSQL Cluster ......................................................................... 494

18.6.1. Upgrading Data via pg_dumpall.............................................................. 49518.6.2. Upgrading Data via pg_upgrade .............................................................. 49618.6.3. Upgrading Data via Replication............................................................... 496

18.7. Preventing Server Spoofing .................................................................................. 49718.8. Encryption Options............................................................................................... 49718.9. Secure TCP/IP Connections with SSL ................................................................. 498

18.9.1. Using Client Certificates .......................................................................... 49918.9.2. SSL Server File Usage ............................................................................. 50018.9.3. Creating a Self-signed Certificate ............................................................ 500

18.10. Secure TCP/IP Connections with SSH Tunnels ................................................. 50118.11. Registering Event Log on Windows................................................................... 502

19. Server Configuration ......................................................................................................... 50319.1. Setting Parameters ................................................................................................ 503

19.1.1. Parameter Names and Values................................................................... 50319.1.2. Parameter Interaction via the Configuration File..................................... 50319.1.3. Parameter Interaction via SQL................................................................. 50419.1.4. Parameter Interaction via the Shell .......................................................... 50519.1.5. Managing Configuration File Contents.................................................... 505

19.2. File Locations ....................................................................................................... 50619.3. Connections and Authentication........................................................................... 507

19.3.1. Connection Settings ................................................................................. 50719.3.2. Security and Authentication..................................................................... 510

19.4. Resource Consumption......................................................................................... 51219.4.1. Memory.................................................................................................... 51219.4.2. Disk .......................................................................................................... 51419.4.3. Kernel Resource Usage............................................................................ 51519.4.4. Cost-based Vacuum Delay ....................................................................... 51519.4.5. Background Writer................................................................................... 51619.4.6. Asynchronous Behavior........................................................................... 517

19.5. Write Ahead Log .................................................................................................. 51919.5.1. Settings..................................................................................................... 51919.5.2. Checkpoints.............................................................................................. 52319.5.3. Archiving ................................................................................................. 524

19.6. Replication............................................................................................................ 52519.6.1. Sending Server(s)..................................................................................... 52519.6.2. Master Server ........................................................................................... 52619.6.3. Standby Servers ....................................................................................... 527

19.7. Query Planning..................................................................................................... 52919.7.1. Planner Method Configuration................................................................. 52919.7.2. Planner Cost Constants ............................................................................ 53019.7.3. Genetic Query Optimizer......................................................................... 53119.7.4. Other Planner Options.............................................................................. 532

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19.8. Error Reporting and Logging ............................................................................... 53419.8.1. Where To Log .......................................................................................... 53419.8.2. When To Log ........................................................................................... 53719.8.3. What To Log ............................................................................................ 53919.8.4. Using CSV-Format Log Output ............................................................... 54219.8.5. Process Title............................................................................................. 543

19.9. Run-time Statistics................................................................................................ 54419.9.1. Query and Index Statistics Collector ....................................................... 54419.9.2. Statistics Monitoring................................................................................ 545

19.10. Automatic Vacuuming ........................................................................................ 54519.11. Client Connection Defaults ................................................................................ 547

19.11.1. Statement Behavior ................................................................................ 54719.11.2. Locale and Formatting ........................................................................... 55119.11.3. Shared Library Preloading ..................................................................... 55319.11.4. Other Defaults ........................................................................................ 554

19.12. Lock Management .............................................................................................. 55519.13. Version and Platform Compatibility................................................................... 556

19.13.1. Previous PostgreSQL Versions .............................................................. 55619.13.2. Platform and Client Compatibility......................................................... 557

19.14. Error Handling.................................................................................................... 55819.15. Preset Options..................................................................................................... 55819.16. Customized Options ........................................................................................... 56019.17. Developer Options .............................................................................................. 56019.18. Short Options...................................................................................................... 563

20. Client Authentication ........................................................................................................ 56420.1. The pg_hba.conf File ........................................................................................ 56420.2. User Name Maps .................................................................................................. 57020.3. Authentication Methods ....................................................................................... 572

20.3.1. Trust Authentication ................................................................................ 57220.3.2. Password Authentication ......................................................................... 57220.3.3. GSSAPI Authentication ........................................................................... 57320.3.4. SSPI Authentication................................................................................. 57420.3.5. Ident Authentication................................................................................. 57520.3.6. Peer Authentication.................................................................................. 57620.3.7. LDAP Authentication .............................................................................. 57620.3.8. RADIUS Authentication.......................................................................... 57820.3.9. Certificate Authentication ........................................................................ 57920.3.10. PAM Authentication .............................................................................. 57920.3.11. BSD Authentication ............................................................................... 580

20.4. Authentication Problems ...................................................................................... 58021. Database Roles .................................................................................................................. 582

21.1. Database Roles ..................................................................................................... 58221.2. Role Attributes...................................................................................................... 58321.3. Role Membership ................................................................................................. 58421.4. Dropping Roles..................................................................................................... 58521.5. Default Roles ........................................................................................................ 58621.6. Function and Trigger Security .............................................................................. 587

22. Managing Databases ......................................................................................................... 58822.1. Overview .............................................................................................................. 58822.2. Creating a Database.............................................................................................. 58822.3. Template Databases .............................................................................................. 58922.4. Database Configuration ........................................................................................ 590

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22.5. Destroying a Database .......................................................................................... 59122.6. Tablespaces........................................................................................................... 591

23. Localization....................................................................................................................... 59423.1. Locale Support...................................................................................................... 594

23.1.1. Overview.................................................................................................. 59423.1.2. Behavior ................................................................................................... 59523.1.3. Problems .................................................................................................. 596

23.2. Collation Support.................................................................................................. 59623.2.1. Concepts................................................................................................... 59623.2.2. Managing Collations................................................................................ 598

23.3. Character Set Support........................................................................................... 59923.3.1. Supported Character Sets......................................................................... 59923.3.2. Setting the Character Set.......................................................................... 60223.3.3. Automatic Character Set Conversion Between Server and Client........... 60323.3.4. Further Reading ....................................................................................... 605

24. Routine Database Maintenance Tasks............................................................................... 60624.1. Routine Vacuuming .............................................................................................. 606

24.1.1. Vacuuming Basics.................................................................................... 60624.1.2. Recovering Disk Space ............................................................................ 60724.1.3. Updating Planner Statistics ...................................................................... 60824.1.4. Updating The Visibility Map ................................................................... 60924.1.5. Preventing Transaction ID Wraparound Failures..................................... 609

24.1.5.1. Multixacts and Wraparound ........................................................ 61224.1.6. The Autovacuum Daemon ....................................................................... 612

24.2. Routine Reindexing .............................................................................................. 61324.3. Log File Maintenance........................................................................................... 614

25. Backup and Restore .......................................................................................................... 61625.1. SQL Dump............................................................................................................ 616

25.1.1. Restoring the Dump ................................................................................. 61625.1.2. Using pg_dumpall.................................................................................... 61725.1.3. Handling Large Databases ....................................................................... 618

25.2. File System Level Backup.................................................................................... 61925.3. Continuous Archiving and Point-in-Time Recovery (PITR)................................ 620

25.3.1. Setting Up WAL Archiving...................................................................... 62125.3.2. Making a Base Backup ............................................................................ 62325.3.3. Making a Base Backup Using the Low Level API .................................. 624

25.3.3.1. Making a non-exclusive low level backup .................................. 62425.3.3.2. Making an exclusive low level backup........................................ 62525.3.3.3. Backing up the data directory...................................................... 626

25.3.4. Recovering Using a Continuous Archive Backup ................................... 62725.3.5. Timelines.................................................................................................. 62825.3.6. Tips and Examples ................................................................................... 629

25.3.6.1. Standalone Hot Backups ............................................................. 62925.3.6.2. Compressed Archive Logs .......................................................... 63025.3.6.3. archive_command Scripts ........................................................ 630

25.3.7. Caveats ..................................................................................................... 63126. High Availability, Load Balancing, and Replication......................................................... 632

26.1. Comparison of Different Solutions....................................................................... 63226.2. Log-Shipping Standby Servers............................................................................. 635

26.2.1. Planning ................................................................................................... 63626.2.2. Standby Server Operation ........................................................................ 63626.2.3. Preparing the Master for Standby Servers ............................................... 637

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26.2.4. Setting Up a Standby Server .................................................................... 63726.2.5. Streaming Replication.............................................................................. 638

26.2.5.1. Authentication ............................................................................. 63926.2.5.2. Monitoring................................................................................... 639

26.2.6. Replication Slots ...................................................................................... 64026.2.6.1. Querying and manipulating replication slots .............................. 64026.2.6.2. Configuration Example ............................................................... 640

26.2.7. Cascading Replication ............................................................................. 64126.2.8. Synchronous Replication ......................................................................... 641

26.2.8.1. Basic Configuration..................................................................... 64226.2.8.2. Multiple Synchronous Standbys.................................................. 64226.2.8.3. Planning for Performance............................................................ 64326.2.8.4. Planning for High Availability .................................................... 643

26.2.9. Continuous archiving in standby ............................................................. 64426.3. Failover ................................................................................................................. 64426.4. Alternative Method for Log Shipping .................................................................. 645

26.4.1. Implementation ........................................................................................ 64626.4.2. Record-based Log Shipping..................................................................... 647

26.5. Hot Standby .......................................................................................................... 64726.5.1. User’s Overview....................................................................................... 64726.5.2. Handling Query Conflicts ........................................................................ 64926.5.3. Administrator’s Overview........................................................................ 65126.5.4. Hot Standby Parameter Reference ........................................................... 65426.5.5. Caveats ..................................................................................................... 654

27. Recovery Configuration .................................................................................................... 65527.1. Archive Recovery Settings ................................................................................... 65527.2. Recovery Target Settings ...................................................................................... 65627.3. Standby Server Settings........................................................................................ 657

28. Monitoring Database Activity........................................................................................... 65928.1. Standard Unix Tools ............................................................................................. 65928.2. The Statistics Collector......................................................................................... 660

28.2.1. Statistics Collection Configuration .......................................................... 66028.2.2. Viewing Statistics..................................................................................... 66128.2.3. Statistics Functions .................................................................................. 680

28.3. Viewing Locks...................................................................................................... 68328.4. Progress Reporting ............................................................................................... 683

28.4.1. VACUUM Progress Reporting................................................................. 68328.5. Dynamic Tracing .................................................................................................. 685

28.5.1. Compiling for Dynamic Tracing.............................................................. 68628.5.2. Built-in Probes ......................................................................................... 68628.5.3. Using Probes ............................................................................................ 69428.5.4. Defining New Probes ............................................................................... 695

29. Monitoring Disk Usage..................................................................................................... 69729.1. Determining Disk Usage ...................................................................................... 69729.2. Disk Full Failure................................................................................................... 698

30. Reliability and the Write-Ahead Log................................................................................ 69930.1. Reliability ............................................................................................................. 69930.2. Write-Ahead Logging (WAL) .............................................................................. 70130.3. Asynchronous Commit......................................................................................... 70130.4. WAL Configuration .............................................................................................. 70330.5. WAL Internals ...................................................................................................... 706

31. Regression Tests................................................................................................................ 707

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31.1. Running the Tests ................................................................................................. 70731.1.1. Running the Tests Against a Temporary Installation ............................... 70731.1.2. Running the Tests Against an Existing Installation ................................. 70731.1.3. Additional Test Suites .............................................................................. 70831.1.4. Locale and Encoding................................................................................ 70831.1.5. Extra Tests................................................................................................ 70931.1.6. Testing Hot Standby................................................................................. 709

31.2. Test Evaluation ..................................................................................................... 71031.2.1. Error Message Differences....................................................................... 71031.2.2. Locale Differences ................................................................................... 71031.2.3. Date and Time Differences ...................................................................... 71131.2.4. Floating-Point Differences....................................................................... 71131.2.5. Row Ordering Differences ....................................................................... 71131.2.6. Insufficient Stack Depth........................................................................... 71231.2.7. The “random” Test ................................................................................... 71231.2.8. Configuration Parameters......................................................................... 712

31.3. Variant Comparison Files ..................................................................................... 71231.4. TAP Tests.............................................................................................................. 71331.5. Test Coverage Examination.................................................................................. 714

IV. Client Interfaces ....................................................................................................................... 71532. libpq - C Library ............................................................................................................... 717

32.1. Database Connection Control Functions .............................................................. 71732.1.1. Connection Strings................................................................................... 723

32.1.1.1. Keyword/Value Connection Strings ............................................ 72332.1.1.2. Connection URIs ......................................................................... 723

32.1.2. Parameter Key Words .............................................................................. 72432.2. Connection Status Functions ................................................................................ 72832.3. Command Execution Functions ........................................................................... 733

32.3.1. Main Functions ........................................................................................ 73332.3.2. Retrieving Query Result Information ...................................................... 74032.3.3. Retrieving Other Result Information ....................................................... 74432.3.4. Escaping Strings for Inclusion in SQL Commands ................................. 745

32.4. Asynchronous Command Processing ................................................................... 74732.5. Retrieving Query Results Row-By-Row .............................................................. 75132.6. Canceling Queries in Progress.............................................................................. 75232.7. The Fast-Path Interface......................................................................................... 75332.8. Asynchronous Notification................................................................................... 75432.9. Functions Associated with the COPY Command .................................................. 755

32.9.1. Functions for Sending COPY Data............................................................ 75632.9.2. Functions for Receiving COPY Data......................................................... 75732.9.3. Obsolete Functions for COPY ................................................................... 757

32.10. Control Functions ............................................................................................... 75932.11. Miscellaneous Functions .................................................................................... 76132.12. Notice Processing ............................................................................................... 76332.13. Event System ...................................................................................................... 764

32.13.1. Event Types............................................................................................ 76432.13.2. Event Callback Procedure...................................................................... 76632.13.3. Event Support Functions........................................................................ 76732.13.4. Event Example ....................................................................................... 768

32.14. Environment Variables ....................................................................................... 77032.15. The Password File .............................................................................................. 772

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32.16. The Connection Service File .............................................................................. 77232.17. LDAP Lookup of Connection Parameters .......................................................... 77332.18. SSL Support........................................................................................................ 774

32.18.1. Client Verification of Server Certificates ............................................... 77432.18.2. Client Certificates................................................................................... 77532.18.3. Protection Provided in Different Modes ................................................ 77532.18.4. SSL Client File Usage............................................................................ 77732.18.5. SSL Library Initialization ...................................................................... 777

32.19. Behavior in Threaded Programs ......................................................................... 77832.20. Building libpq Programs..................................................................................... 77932.21. Example Programs.............................................................................................. 780

33. Large Objects .................................................................................................................... 78933.1. Introduction .......................................................................................................... 78933.2. Implementation Features ...................................................................................... 78933.3. Client Interfaces.................................................................................................... 789

33.3.1. Creating a Large Object ........................................................................... 79033.3.2. Importing a Large Object......................................................................... 79033.3.3. Exporting a Large Object......................................................................... 79133.3.4. Opening an Existing Large Object........................................................... 79133.3.5. Writing Data to a Large Object................................................................ 79133.3.6. Reading Data from a Large Object .......................................................... 79233.3.7. Seeking in a Large Object........................................................................ 79233.3.8. Obtaining the Seek Position of a Large Object........................................ 79233.3.9. Truncating a Large Object ....................................................................... 79333.3.10. Closing a Large Object Descriptor ........................................................ 79333.3.11. Removing a Large Object ...................................................................... 793

33.4. Server-side Functions ........................................................................................... 79433.5. Example Program ................................................................................................. 795

34. ECPG - Embedded SQL in C............................................................................................ 80034.1. The Concept.......................................................................................................... 80034.2. Managing Database Connections ......................................................................... 800

34.2.1. Connecting to the Database Server ..........................................

The PostgreSQL Global Development Group · 8.5. Date/Time Types.....126 8.5.1. Date/Time...

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