SpirirHost Support Centre: MySQL Reference Manual p.335

<< previous page -- table of contents -- next page >>

Chapter_1

Chapter_2

Chapter_3

Chapter_4

Chapter_5

Return to Table of Contents

Table of Contents
1. General Information
2. MySQL Installation
3. Tutorial Introduction
4. Database Administration
5. MySQL Optimisation
6. MySQL Language Reference
7. MySQL Table Types
8. MySQL APIs
9. Extending MySQL

Chapter 5: MySQL Optimisation 335 to disk). Transaction databases in general are not very good at generating summary tables from log tables, as in this case row locking is almost useless. To get your application really database-independent, you need to dene an easy extendable interface through which you manipulate your data. As C++ is available on most systems, it makes sense to use a C++ classes interface to the databases. If you use some specic feature for some database (like the REPLACE command in MySQL), you should code a method for the other SQL servers to implement the same feature (but slower). With MySQL you can use the /*! */ syntax to add MySQL-specic keywords to a query. The code inside /**/ will be treated as a comment (ignored) by most other SQL servers. If high performance is more important than exactness, as in some web applications, it is possibile to create an application layer that caches all results to give you even higher performance. By letting old results 'expire' after a while, you can keep the cache reasonably fresh. This provides a method to handle high load spikes, in which case you can dynamically increase the cache and set the expire timeout higher until things get back to normal. In this case the table creation information should contain information of the initial size of the cache and how often the table should normally be refreshed. 5.1.3 What Have We Used MySQL For? During MySQL initial development, the features of MySQL were made to t our largest customer. They handle data warehousing for a couple of the biggest retailers in Sweden. From all stores, we get weekly summaries of all bonus card transactions, and we are expected to provide useful information for the store owners to help them nd how their advertisement campaigns are aecting their customers. The data is quite huge (about 7 million summary transactions per month), and we have data for 4-10 years that we need to present to the users. We got weekly requests from the customers that they want to get 'instant' access to new reports from this data. We solved this by storing all information per month in compressed 'transaction' tables. We have a set of simple macros (script) that generates summary tables grouped by dierent criteria (product group, customer id, store ...) from the transaction tables. The reports are web pages that are dynamically generated by a small Perl script that parses a web page, executes the SQL statements in it, and inserts the results. We would have used PHP or mod perl instead but they were not available at that time. For graphical data we wrote a simple tool in C that can produce GIFs based on the result of a SQL query (with some processing of the result). This is also dynamically executed from the Perl script that parses the HTML les. In most cases a new report can simply be done by copying an existing script and modifying the SQL query in it. In some cases, we will need to add more elds to an existing summary table or generate a new one, but this is also quite simple, as we keep all transactions tables on disk. (Currently we have at least 50G of transactions tables and 200G of other customer data.) We also let our customers access the summary tables directly with ODBC so that the advanced users can themselves experiment with the data.

MySQL Reference Manual

Home
Hosting Plans \| Domain Registration \| About Us \| Contact Us \| Site Map Terms of Use \| Privacy Policy \| Guarantees Merchant Accounts

SpiritHost - web hosting for spiritual and education sites SpiritHit.com - Religious and Spiritual Portal Copyright © 2002 Dyntex Group, Inc. All Rights Reserved

Return to Table of Contents	Back to top

Web Hosting: Manuals & FAQ's

1. Unix-Based Web Hosting
2. Unix Dedicated Servers
3. Windows Dedicated Servers
4. CuteFTP User’s Guide
5. CuteHTML User’s Guide
6. WS_FTP Pro User's Guide
7. Miva Order User's Guide
8. Miva Merchant User's Guide