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Performance and Tuning Guide Volumes 1 - 3 (Online Only) |
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| Chapter 7 Data Storage |
Chapter 7
This chapter explains how Adaptive Server stores data rows on pages and how those pages are used in select and data modification statements, when there are no indexes.
It lays the foundation for understanding how to improve Adaptive Server's performance by creating indexes, tuning your queries, and addressing object storage issues.
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| Performance gains through query optimization |
| Query processing and page reads |
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| Adaptive Server pages |
| Page headers and page sizes |
| Varying logical page sizes |
| Data and index pages |
| Large Object (LOB) Pages |
| Extents |
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| Pages that manage space allocation |
| Global allocation map pages |
| Allocation pages |
| Object allocation map pages |
| How OAM pages and allocation pages manage object storage |
| Page allocation keeps an object's pages together |
| sysindexes table and data access |
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| Space overheads |
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| Number of columns and size |
| Number of rows per data page |
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| Maximum numbers |
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| Heaps of data: tables without clustered indexes |
| Lock schemes and differences between heaps |
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| Select operations on heaps |
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| Inserting data into an allpages-locked heap table |
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| Inserting data into a data-only-locked heap table |
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| Deleting data from a heap table |
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| Updating data on a heap table |
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| How Adaptive Server performs I/O for heap operations |
| Sequential prefetch, or large I/O |
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| Caches and object bindings |
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| Heaps, I/O, and cache strategies |
| Select operations and caching |
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| Data modification and caching |
| Asynchronous prefetch and I/O on heap tables |
| Heaps: pros and cons |
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| Maintaining heaps |
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| Methods |
| Transaction log: a special heap table |
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