
PostgreSQL 14.3 Documentation
9.21. Aggregate Functions ........................................................................... 345
9.22. Window Functions ............................................................................. 352
9.23. Subquery Expressions ......................................................................... 354
9.24. Row and Array Comparisons ............................................................... 356
9.25. Set Returning Functions ...................................................................... 359
9.26. System Information Functions and Operators .......................................... 362
9.27. System Administration Functions .......................................................... 379
9.28. Trigger Functions ............................................................................... 395
9.29. Event Trigger Functions ...................................................................... 396
9.30. Statistics Information Functions ............................................................ 399
10. Type Conversion .......................................................................................... 401
10.1. Overview .......................................................................................... 401
10.2. Operators .......................................................................................... 402
10.3. Functions .......................................................................................... 406
10.4. Value Storage .................................................................................... 410
10.5. UNION, CASE, and Related Constructs .................................................. 411
10.6. SELECT Output Columns .................................................................... 412
11. Indexes ....................................................................................................... 414
11.1. Introduction ....................................................................................... 414
11.2. Index Types ...................................................................................... 415
11.3. Multicolumn Indexes .......................................................................... 417
11.4. Indexes and ORDER BY ..................................................................... 418
11.5. Combining Multiple Indexes ................................................................ 419
11.6. Unique Indexes .................................................................................. 419
11.7. Indexes on Expressions ....................................................................... 420
11.8. Partial Indexes ................................................................................... 420
11.9. Index-Only Scans and Covering Indexes ................................................ 423
11.10. Operator Classes and Operator Families ................................................ 426
11.11. Indexes and Collations ...................................................................... 427
11.12. Examining Index Usage ..................................................................... 428
12. Full Text Search ........................................................................................... 430
12.1. Introduction ....................................................................................... 430
12.2. Tables and Indexes ............................................................................. 434
12.3. Controlling Text Search ...................................................................... 436
12.4. Additional Features ............................................................................ 443
12.5. Parsers ............................................................................................. 449
12.6. Dictionaries ....................................................................................... 450
12.7. Configuration Example ....................................................................... 460
12.8. Testing and Debugging Text Search ...................................................... 461
12.9. Preferred Index Types for Text Search ................................................... 466
12.10. psql Support .................................................................................... 467
12.11. Limitations ...................................................................................... 470
13. Concurrency Control ..................................................................................... 471
13.1. Introduction ....................................................................................... 471
13.2. Transaction Isolation ........................................................................... 471
13.3. Explicit Locking ................................................................................ 477
13.4. Data Consistency Checks at the Application Level ................................... 482
13.5. Caveats ............................................................................................. 484
13.6. Locking and Indexes ........................................................................... 484
14. Performance Tips ......................................................................................... 486
14.1. Using EXPLAIN ................................................................................ 486
14.2. Statistics Used by the Planner .............................................................. 498
14.3. Controlling the Planner with Explicit JOIN Clauses ................................. 503
14.4. Populating a Database ......................................................................... 505
14.5. Non-Durable Settings .......................................................................... 508
15. Parallel Query .............................................................................................. 509
15.1. How Parallel Query Works .................................................................. 509
15.2. When Can Parallel Query Be Used? ...................................................... 510
v
评论0