SQL Performance Explained helps developers to improve database performance. The focus is on SQL—it covers all major SQL databases without getting lost in the details of any one specific product.
Starting with the basics of indexing and the WHERE clause, SQL Performance Explained guides developers through all parts of an SQL statement and explains the pitfalls of object-relational mapping (ORM) tools like Hibernate.
Topics covered include
• Using multi-column indexes
• Correctly applying SQL functions
• Efficient use of LIKE queries
• Optimizing join operations
• Clustering data to improve performance
• Pipelined execution of ORDER BY and GROUP BY
• Getting the best performance for pagination queries
• Understanding the scalability of databases
Its systematic structure makes SQL Performance Explained both a textbook and a reference manual that should be on every developer’s bookshelf.
Covers all major databases: Oracle® Database, SQL Server®, PostgreSQL, MySQL
What readers say
“This book is definitively worth having in the company library.” — Joe Celko
Author(s): Markus Winand
Publisher: Markus Winand
Year: 2023
Language: English
Pages: 369
............................................................................................ vi
1. Anatomy of an Index ...................................................................... 1
The Index Leaf Nodes .................................................................. 2
The Search Tree (B-Tree) .............................................................. 4
Slow Indexes, Part I .................................................................... 6
2. The Where Clause ......................................................................... 9
The Equality Operator .................................................................. 9
Primary Keys ....................................................................... 10
Concatenated Indexes .......................................................... 12
Slow Indexes, Part II ............................................................ 18
Functions .................................................................................. 24
Case-Insensitive Search Using UPPERor LOWER.......................... 24
User-Defined Functions ........................................................ 29
Over-Indexing ...................................................................... 31
Parameterized Queries ............................................................... 32
Searching for Ranges ................................................................. 39
Greater, Less and BETWEEN..................................................... 39
Indexing LIKEFilters ............................................................. 45
Index Merge ........................................................................ 49
Partial Indexes ........................................................................... 51
NULLin the Oracle Database ....................................................... 53
Indexing NULL....................................................................... 54
NOT NULLConstraints ............................................................ 56
Emulating Partial Indexes ..................................................... 60
Obfuscated Conditions ............................................................... 62
Date Types .......................................................................... 62
Numeric Strings .................................................................. 68
Combining Columns ............................................................ 70
Smart Logic ......................................................................... 72
Math .................................................................................. 77
3. Performance and Scalability ......................................................... 79 Performance Impacts of Data Volume ......................................... 80 Performance Impacts of System Load .......................................... 85 Response Time and Throughput ................................................. 87
4. The Join Operation ....................................................................... 91
Nested Loops ............................................................................ 92
Hash Join ................................................................................. 101
Sort Merge .............................................................................. 109
5. Clustering Data ........................................................................... 111
Index Filter Predicates Used Intentionally ................................... 112
Index-Only Scan ........................................................................ 116
Index-Organized Tables ............................................................. 122
6. Sorting and Grouping ................................................................. 129
Indexing Order By .................................................................... 130
Indexing ASC, DESCand NULLS FIRST/LAST...................................... 134
Indexing Group By .................................................................... 139
7. Partial Results ............................................................................ 143
Querying Top-N Rows ............................................................... 143
Paging Through Results ............................................................ 147
Using Window Functions for Pagination .................................... 156
8. Modifying Data .......................................................................... 159
Insert ...................................................................................... 159
Delete ...................................................................................... 162
Update .................................................................................... 163
A. Execution Plans .......................................................................... 165
Oracle Database ....................................................................... 166
PostgreSQL ............................................................................... 172
SQL Server ............................................................................... 180
MySQL ..................................................................................... 188
Index ............................................................................................. 193 v
