Table Of ContentPostgreSQL 9.1.24 Documentation
The PostgreSQL Global Development Group
PostgreSQL 9.1.24 Documentation
by The PostgreSQL Global Development Group
Copyright © 1996-2016 The PostgreSQL Global Development Group
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Table of Contents
Preface .............................................................................................................................................lviii
1. What is PostgreSQL? ..........................................................................................................lviii
2. A Brief History of PostgreSQL.............................................................................................lix
2.1. The Berkeley POSTGRES Project ...........................................................................lix
2.2. Postgres95.................................................................................................................lix
2.3. PostgreSQL................................................................................................................ lx
3. Conventions............................................................................................................................ lx
4. Further Information...............................................................................................................lxi
5. Bug Reporting Guidelines.....................................................................................................lxi
5.1. Identifying Bugs ......................................................................................................lxii
5.2. What to Report ........................................................................................................lxii
5.3. Where to Report Bugs ............................................................................................ lxiv
I. Tutorial ............................................................................................................................................. 1
1. Getting Started ........................................................................................................................ 1
1.1. Installation .................................................................................................................. 1
1.2. Architectural Fundamentals........................................................................................ 1
1.3. Creating a Database.................................................................................................... 2
1.4. Accessing a Database ................................................................................................. 3
2. The SQL Language ................................................................................................................. 5
2.1. Introduction ................................................................................................................ 5
2.2. Concepts ..................................................................................................................... 5
2.3. Creating a New Table ................................................................................................. 5
2.4. Populating a Table With Rows ................................................................................... 6
2.5. Querying a Table ........................................................................................................ 7
2.6. Joins Between Tables.................................................................................................. 9
2.7. Aggregate Functions................................................................................................. 11
2.8. Updates ..................................................................................................................... 12
2.9. Deletions................................................................................................................... 13
3. Advanced Features ................................................................................................................ 14
3.1. Introduction .............................................................................................................. 14
3.2. Views ........................................................................................................................ 14
3.3. Foreign Keys............................................................................................................. 14
3.4. Transactions.............................................................................................................. 15
3.5. Window Functions.................................................................................................... 17
3.6. Inheritance ................................................................................................................ 20
3.7. Conclusion................................................................................................................ 21
II. The SQL Language...................................................................................................................... 22
4. SQL Syntax ........................................................................................................................... 24
4.1. Lexical Structure....................................................................................................... 24
4.1.1. Identifiers and Key Words............................................................................ 24
4.1.2. Constants...................................................................................................... 26
4.1.2.1. String Constants .............................................................................. 26
4.1.2.2. String Constants with C-style Escapes............................................ 26
4.1.2.3. String Constants with Unicode Escapes.......................................... 28
4.1.2.4. Dollar-quoted String Constants ....................................................... 28
4.1.2.5. Bit-string Constants......................................................................... 29
4.1.2.6. Numeric Constants .......................................................................... 29
4.1.2.7. Constants of Other Types ................................................................ 30
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4.1.3. Operators...................................................................................................... 31
4.1.4. Special Characters........................................................................................ 31
4.1.5. Comments .................................................................................................... 32
4.1.6. Operator Precedence .................................................................................... 32
4.2. Value Expressions..................................................................................................... 33
4.2.1. Column References...................................................................................... 34
4.2.2. Positional Parameters................................................................................... 34
4.2.3. Subscripts..................................................................................................... 35
4.2.4. Field Selection ............................................................................................. 35
4.2.5. Operator Invocations.................................................................................... 36
4.2.6. Function Calls .............................................................................................. 36
4.2.7. Aggregate Expressions................................................................................. 36
4.2.8. Window Function Calls................................................................................ 38
4.2.9. Type Casts .................................................................................................... 39
4.2.10. Collation Expressions ................................................................................ 40
4.2.11. Scalar Subqueries....................................................................................... 41
4.2.12. Array Constructors..................................................................................... 41
4.2.13. Row Constructors....................................................................................... 43
4.2.14. Expression Evaluation Rules ..................................................................... 44
4.3. Calling Functions...................................................................................................... 45
4.3.1. Using Positional Notation ............................................................................ 46
4.3.2. Using Named Notation ................................................................................ 46
4.3.3. Using Mixed Notation.................................................................................. 47
5. Data Definition ...................................................................................................................... 48
5.1. Table Basics.............................................................................................................. 48
5.2. Default Values .......................................................................................................... 49
5.3. Constraints ................................................................................................................ 50
5.3.1. Check Constraints ........................................................................................ 50
5.3.2. Not-Null Constraints.................................................................................... 52
5.3.3. Unique Constraints....................................................................................... 53
5.3.4. Primary Keys................................................................................................ 54
5.3.5. Foreign Keys ................................................................................................ 54
5.3.6. Exclusion Constraints .................................................................................. 57
5.4. System Columns....................................................................................................... 57
5.5. Modifying Tables...................................................................................................... 59
5.5.1. Adding a Column......................................................................................... 59
5.5.2. Removing a Column .................................................................................... 59
5.5.3. Adding a Constraint ..................................................................................... 60
5.5.4. Removing a Constraint ................................................................................ 60
5.5.5. Changing a Column’s Default Value............................................................ 60
5.5.6. Changing a Column’s Data Type ................................................................. 61
5.5.7. Renaming a Column .................................................................................... 61
5.5.8. Renaming a Table ........................................................................................ 61
5.6. Privileges .................................................................................................................. 61
5.7. Schemas.................................................................................................................... 62
5.7.1. Creating a Schema ....................................................................................... 63
5.7.2. The Public Schema ...................................................................................... 64
5.7.3. The Schema Search Path.............................................................................. 64
5.7.4. Schemas and Privileges................................................................................ 65
5.7.5. The System Catalog Schema ....................................................................... 65
5.7.6. Usage Patterns.............................................................................................. 66
5.7.7. Portability..................................................................................................... 66
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5.8. Inheritance ................................................................................................................ 67
5.8.1. Caveats ......................................................................................................... 69
5.9. Partitioning ............................................................................................................... 70
5.9.1. Overview...................................................................................................... 70
5.9.2. Implementing Partitioning ........................................................................... 71
5.9.3. Managing Partitions ..................................................................................... 74
5.9.4. Partitioning and Constraint Exclusion ......................................................... 74
5.9.5. Alternative Partitioning Methods................................................................. 76
5.9.6. Caveats ......................................................................................................... 76
5.10. Foreign Data ........................................................................................................... 77
5.11. Other Database Objects .......................................................................................... 78
5.12. Dependency Tracking............................................................................................. 78
6. Data Manipulation................................................................................................................. 80
6.1. Inserting Data ........................................................................................................... 80
6.2. Updating Data........................................................................................................... 81
6.3. Deleting Data............................................................................................................ 82
7. Queries .................................................................................................................................. 83
7.1. Overview .................................................................................................................. 83
7.2. Table Expressions ..................................................................................................... 83
7.2.1. The FROM Clause.......................................................................................... 84
7.2.1.1. Joined Tables ................................................................................... 84
7.2.1.2. Table and Column Aliases............................................................... 88
7.2.1.3. Subqueries ....................................................................................... 89
7.2.1.4. Table Functions ............................................................................... 89
7.2.2. The WHERE Clause........................................................................................ 90
7.2.3. The GROUP BY and HAVING Clauses........................................................... 91
7.2.4. Window Function Processing ...................................................................... 93
7.3. Select Lists................................................................................................................ 94
7.3.1. Select-List Items .......................................................................................... 94
7.3.2. Column Labels ............................................................................................. 94
7.3.3. DISTINCT .................................................................................................... 95
7.4. Combining Queries................................................................................................... 95
7.5. Sorting Rows ............................................................................................................ 96
7.6. LIMIT and OFFSET................................................................................................... 97
7.7. VALUES Lists ............................................................................................................ 98
7.8. WITH Queries (Common Table Expressions) ........................................................... 98
7.8.1. SELECT in WITH........................................................................................... 98
7.8.2. Data-Modifying Statements in WITH ......................................................... 102
8. Data Types........................................................................................................................... 104
8.1. Numeric Types........................................................................................................ 105
8.1.1. Integer Types.............................................................................................. 106
8.1.2. Arbitrary Precision Numbers ..................................................................... 106
8.1.3. Floating-Point Types .................................................................................. 108
8.1.4. Serial Types................................................................................................ 109
8.2. Monetary Types ...................................................................................................... 110
8.3. Character Types ...................................................................................................... 110
8.4. Binary Data Types .................................................................................................. 112
8.4.1. bytea Hex Format..................................................................................... 113
8.4.2. bytea Escape Format................................................................................ 113
8.5. Date/Time Types..................................................................................................... 115
8.5.1. Date/Time Input ......................................................................................... 116
8.5.1.1. Dates.............................................................................................. 117
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8.5.1.2. Times ............................................................................................. 117
8.5.1.3. Time Stamps.................................................................................. 118
8.5.1.4. Special Values ............................................................................... 119
8.5.2. Date/Time Output ...................................................................................... 120
8.5.3. Time Zones ................................................................................................ 121
8.5.4. Interval Input.............................................................................................. 122
8.5.5. Interval Output ........................................................................................... 124
8.5.6. Internals...................................................................................................... 125
8.6. Boolean Type.......................................................................................................... 125
8.7. Enumerated Types .................................................................................................. 126
8.7.1. Declaration of Enumerated Types.............................................................. 126
8.7.2. Ordering ..................................................................................................... 126
8.7.3. Type Safety ................................................................................................ 127
8.7.4. Implementation Details.............................................................................. 128
8.8. Geometric Types..................................................................................................... 128
8.8.1. Points ......................................................................................................... 128
8.8.2. Line Segments............................................................................................ 129
8.8.3. Boxes.......................................................................................................... 129
8.8.4. Paths........................................................................................................... 129
8.8.5. Polygons..................................................................................................... 130
8.8.6. Circles ........................................................................................................ 130
8.9. Network Address Types.......................................................................................... 130
8.9.1. inet........................................................................................................... 131
8.9.2. cidr........................................................................................................... 131
8.9.3. inet vs. cidr............................................................................................ 131
8.9.4. macaddr .................................................................................................... 132
8.10. Bit String Types .................................................................................................... 132
8.11. Text Search Types................................................................................................. 133
8.11.1. tsvector ................................................................................................ 133
8.11.2. tsquery .................................................................................................. 134
8.12. UUID Type ........................................................................................................... 135
8.13. XML Type ............................................................................................................ 136
8.13.1. Creating XML Values .............................................................................. 136
8.13.2. Encoding Handling .................................................................................. 137
8.13.3. Accessing XML Values............................................................................ 138
8.14. Arrays ................................................................................................................... 138
8.14.1. Declaration of Array Types...................................................................... 138
8.14.2. Array Value Input..................................................................................... 139
8.14.3. Accessing Arrays ..................................................................................... 140
8.14.4. Modifying Arrays..................................................................................... 142
8.14.5. Searching in Arrays.................................................................................. 145
8.14.6. Array Input and Output Syntax................................................................ 145
8.15. Composite Types .................................................................................................. 147
8.15.1. Declaration of Composite Types.............................................................. 147
8.15.2. Composite Value Input............................................................................. 148
8.15.3. Accessing Composite Types .................................................................... 148
8.15.4. Modifying Composite Types.................................................................... 149
8.15.5. Composite Type Input and Output Syntax............................................... 149
8.16. Object Identifier Types ......................................................................................... 150
8.17. Pseudo-Types........................................................................................................ 152
9. Functions and Operators ..................................................................................................... 154
9.1. Logical Operators ................................................................................................... 154
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9.2. Comparison Operators............................................................................................ 154
9.3. Mathematical Functions and Operators.................................................................. 156
9.4. String Functions and Operators .............................................................................. 159
9.5. Binary String Functions and Operators .................................................................. 173
9.6. Bit String Functions and Operators ........................................................................ 175
9.7. Pattern Matching .................................................................................................... 176
9.7.1. LIKE........................................................................................................... 177
9.7.2. SIMILAR TO Regular Expressions ............................................................ 178
9.7.3. POSIX Regular Expressions ...................................................................... 179
9.7.3.1. Regular Expression Details ........................................................... 182
9.7.3.2. Bracket Expressions ...................................................................... 184
9.7.3.3. Regular Expression Escapes.......................................................... 185
9.7.3.4. Regular Expression Metasyntax.................................................... 187
9.7.3.5. Regular Expression Matching Rules ............................................. 189
9.7.3.6. Limits and Compatibility .............................................................. 190
9.7.3.7. Basic Regular Expressions ............................................................ 191
9.8. Data Type Formatting Functions ............................................................................ 191
9.9. Date/Time Functions and Operators....................................................................... 198
9.9.1. EXTRACT, date_part............................................................................... 202
9.9.2. date_trunc.............................................................................................. 206
9.9.3. AT TIME ZONE.......................................................................................... 206
9.9.4. Current Date/Time ..................................................................................... 207
9.9.5. Delaying Execution.................................................................................... 209
9.10. Enum Support Functions ...................................................................................... 209
9.11. Geometric Functions and Operators ..................................................................... 210
9.12. Network Address Functions and Operators.......................................................... 214
9.13. Text Search Functions and Operators ................................................................... 216
9.14. XML Functions .................................................................................................... 220
9.14.1. Producing XML Content.......................................................................... 220
9.14.1.1. xmlcomment ............................................................................... 220
9.14.1.2. xmlconcat ................................................................................. 221
9.14.1.3. xmlelement ............................................................................... 221
9.14.1.4. xmlforest ................................................................................. 223
9.14.1.5. xmlpi .......................................................................................... 223
9.14.1.6. xmlroot...................................................................................... 224
9.14.1.7. xmlagg........................................................................................ 224
9.14.2. XML Predicates ....................................................................................... 225
9.14.2.1. IS DOCUMENT ............................................................................. 225
9.14.2.2. XMLEXISTS ................................................................................. 225
9.14.2.3. xml_is_well_formed .............................................................. 225
9.14.3. Processing XML ...................................................................................... 226
9.14.4. Mapping Tables to XML.......................................................................... 227
9.15. Sequence Manipulation Functions ....................................................................... 231
9.16. Conditional Expressions....................................................................................... 233
9.16.1. CASE......................................................................................................... 233
9.16.2. COALESCE ................................................................................................ 235
9.16.3. NULLIF..................................................................................................... 235
9.16.4. GREATEST and LEAST.............................................................................. 235
9.17. Array Functions and Operators ............................................................................ 236
9.18. Aggregate Functions............................................................................................. 238
9.19. Window Functions................................................................................................ 241
9.20. Subquery Expressions .......................................................................................... 243
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9.20.1. EXISTS..................................................................................................... 243
9.20.2. IN ............................................................................................................. 244
9.20.3. NOT IN..................................................................................................... 244
9.20.4. ANY/SOME ................................................................................................. 245
9.20.5. ALL ........................................................................................................... 245
9.20.6. Row-wise Comparison............................................................................. 246
9.21. Row and Array Comparisons ............................................................................... 246
9.21.1. IN ............................................................................................................. 246
9.21.2. NOT IN..................................................................................................... 247
9.21.3. ANY/SOME (array) ..................................................................................... 247
9.21.4. ALL (array) ............................................................................................... 248
9.21.5. Row-wise Comparison............................................................................. 248
9.22. Set Returning Functions ....................................................................................... 249
9.23. System Information Functions ............................................................................. 251
9.24. System Administration Functions ........................................................................ 261
9.25. Trigger Functions ................................................................................................. 270
10. Type Conversion................................................................................................................ 272
10.1. Overview .............................................................................................................. 272
10.2. Operators .............................................................................................................. 273
10.3. Functions .............................................................................................................. 276
10.4. Value Storage........................................................................................................ 279
10.5. UNION, CASE, and Related Constructs.................................................................. 280
11. Indexes .............................................................................................................................. 282
11.1. Introduction .......................................................................................................... 282
11.2. Index Types........................................................................................................... 283
11.3. Multicolumn Indexes............................................................................................ 284
11.4. Indexes and ORDER BY......................................................................................... 285
11.5. Combining Multiple Indexes ................................................................................ 286
11.6. Unique Indexes ..................................................................................................... 287
11.7. Indexes on Expressions ........................................................................................ 287
11.8. Partial Indexes ...................................................................................................... 288
11.9. Operator Classes and Operator Families .............................................................. 290
11.10. Indexes and Collations........................................................................................ 292
11.11. Examining Index Usage...................................................................................... 292
12. Full Text Search ................................................................................................................ 294
12.1. Introduction .......................................................................................................... 294
12.1.1. What Is a Document?............................................................................... 295
12.1.2. Basic Text Matching ................................................................................ 295
12.1.3. Configurations.......................................................................................... 296
12.2. Tables and Indexes................................................................................................ 297
12.2.1. Searching a Table ..................................................................................... 297
12.2.2. Creating Indexes ...................................................................................... 298
12.3. Controlling Text Search........................................................................................ 299
12.3.1. Parsing Documents .................................................................................. 299
12.3.2. Parsing Queries ........................................................................................ 300
12.3.3. Ranking Search Results ........................................................................... 302
12.3.4. Highlighting Results ................................................................................ 304
12.4. Additional Features .............................................................................................. 305
12.4.1. Manipulating Documents......................................................................... 305
12.4.2. Manipulating Queries............................................................................... 306
12.4.2.1. Query Rewriting .......................................................................... 307
12.4.3. Triggers for Automatic Updates .............................................................. 308
viii
12.4.4. Gathering Document Statistics ................................................................ 309
12.5. Parsers................................................................................................................... 310
12.6. Dictionaries........................................................................................................... 312
12.6.1. Stop Words............................................................................................... 313
12.6.2. Simple Dictionary .................................................................................... 313
12.6.3. Synonym Dictionary ................................................................................ 315
12.6.4. Thesaurus Dictionary ............................................................................... 316
12.6.4.1. Thesaurus Configuration ............................................................. 317
12.6.4.2. Thesaurus Example ..................................................................... 318
12.6.5. Ispell Dictionary....................................................................................... 319
12.6.6. Snowball Dictionary ................................................................................ 320
12.7. Configuration Example......................................................................................... 320
12.8. Testing and Debugging Text Search ..................................................................... 322
12.8.1. Configuration Testing............................................................................... 322
12.8.2. Parser Testing........................................................................................... 324
12.8.3. Dictionary Testing.................................................................................... 325
12.9. GiST and GIN Index Types .................................................................................. 326
12.10. psql Support........................................................................................................ 327
12.11. Limitations.......................................................................................................... 330
12.12. Migration from Pre-8.3 Text Search................................................................... 330
13. Concurrency Control ......................................................................................................... 331
13.1. Introduction .......................................................................................................... 331
13.2. Transaction Isolation ............................................................................................ 331
13.2.1. Read Committed Isolation Level ............................................................. 332
13.2.2. Repeatable Read Isolation Level.............................................................. 333
13.2.3. Serializable Isolation Level...................................................................... 334
13.3. Explicit Locking ................................................................................................... 336
13.3.1. Table-level Locks ..................................................................................... 336
13.3.2. Row-level Locks ...................................................................................... 339
13.3.3. Deadlocks................................................................................................. 339
13.3.4. Advisory Locks........................................................................................ 340
13.4. Data Consistency Checks at the Application Level.............................................. 341
13.4.1. Enforcing Consistency With Serializable Transactions ........................... 342
13.4.2. Enforcing Consistency With Explicit Blocking Locks ............................ 342
13.5. Caveats.................................................................................................................. 343
13.6. Locking and Indexes............................................................................................. 343
14. Performance Tips .............................................................................................................. 345
14.1. Using EXPLAIN .................................................................................................... 345
14.2. Statistics Used by the Planner .............................................................................. 350
14.3. Controlling the Planner with Explicit JOIN Clauses............................................ 351
14.4. Populating a Database .......................................................................................... 353
14.4.1. Disable Autocommit ................................................................................ 353
14.4.2. Use COPY.................................................................................................. 353
14.4.3. Remove Indexes ....................................................................................... 354
14.4.4. Remove Foreign Key Constraints ............................................................ 354
14.4.5. Increase maintenance_work_mem ........................................................ 354
14.4.6. Increase checkpoint_segments .......................................................... 354
14.4.7. Disable WAL Archival and Streaming Replication ................................. 354
14.4.8. Run ANALYZE Afterwards........................................................................ 355
14.4.9. Some Notes About pg_dump................................................................... 355
14.5. Non-Durable Settings ........................................................................................... 356
ix
III. Server Administration ............................................................................................................. 357
15. Installation from Source Code .......................................................................................... 359
15.1. Short Version ........................................................................................................ 359
15.2. Requirements........................................................................................................ 359
15.3. Getting The Source............................................................................................... 361
15.4. Installation Procedure........................................................................................... 361
15.5. Post-Installation Setup.......................................................................................... 371
15.5.1. Shared Libraries ....................................................................................... 371
15.5.2. Environment Variables ............................................................................. 371
15.6. Supported Platforms ............................................................................................. 372
15.7. Platform-specific Notes ........................................................................................ 373
15.7.1. AIX .......................................................................................................... 373
15.7.1.1. GCC Issues.................................................................................. 373
15.7.1.2. Unix-Domain Sockets Broken..................................................... 374
15.7.1.3. Internet Address Issues................................................................ 374
15.7.1.4. Memory Management ................................................................. 374
References and Resources ................................................................ 375
15.7.2. Cygwin..................................................................................................... 376
15.7.3. HP-UX ..................................................................................................... 377
15.7.4. IRIX ......................................................................................................... 377
15.7.5. MinGW/Native Windows ........................................................................ 378
15.7.5.1. Collecting Crash Dumps on Windows ........................................ 378
15.7.6. SCO OpenServer and SCO UnixWare..................................................... 379
15.7.6.1. Skunkware ................................................................................... 379
15.7.6.2. GNU Make .................................................................................. 379
15.7.6.3. Readline....................................................................................... 379
15.7.6.4. Using the UDK on OpenServer................................................... 379
15.7.6.5. Reading the PostgreSQL Man Pages........................................... 380
15.7.6.6. C99 Issues with the 7.1.1b Feature Supplement ......................... 380
15.7.6.7. Threading on UnixWare .............................................................. 380
15.7.7. Solaris ...................................................................................................... 380
15.7.7.1. Required Tools ............................................................................ 380
15.7.7.2. Problems with OpenSSL ............................................................. 381
15.7.7.3. configure Complains About a Failed Test Program .................... 381
15.7.7.4. 64-bit Build Sometimes Crashes ................................................. 381
15.7.7.5. Compiling for Optimal Performance........................................... 381
15.7.7.6. Using DTrace for Tracing PostgreSQL....................................... 382
16. Installation from Source Code on Windows ..................................................................... 383
16.1. Building with Visual C++ or the Platform SDK .................................................. 383
16.1.1. Requirements ........................................................................................... 384
16.1.2. Special Considerations for 64-bit Windows ............................................ 385
16.1.3. Building ................................................................................................... 385
16.1.4. Cleaning and Installing ............................................................................ 386
16.1.5. Running the Regression Tests .................................................................. 386
16.1.6. Building the Documentation .................................................................... 387
16.2. Building libpq with Visual C++ or Borland C++................................................. 387
16.2.1. Generated Files ........................................................................................ 388
17. Server Setup and Operation .............................................................................................. 389
17.1. The PostgreSQL User Account ............................................................................ 389
17.2. Creating a Database Cluster ................................................................................. 389
17.2.1. Use of Secondary File Systems................................................................ 390
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