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Linux.com: Writing Database Oriented Web-based Applications with Perl - Part II

Mar 12, 2001, 20:28 (1 Talkback[s])
(Other stories by Marcelo Pham)

"There are several databases for Linux. Right now the most used databases are PostgreSQL, mySQL and Oracle. Others not so often used but compatible are mSQL, Informix and DB2. In this installment we will talk a little about each one, how to get them and which one is best tailored to your needs, assuming that you have already designed your application and outlined your database."

"Usually a database is installed in your Linux box and runs as a daemon process to service requests such as inquiries and updates. Each database has its own daemons and they work differently from one flavor to another. For example, Oracle uses a daemon to monitor the database (called Server Manager) and another one for each database (called listener), PostgreSQL only has one daemon for all its databases (called postmaster). These services are just regular processes running on the server in a specific port, like the httpd daemon. Usually you must shut them down with utilities that come with the database; if you kill the running processes or shut down the server without stopping the services, you may damage the database files."

"A database can be running on the same server as the application, or on a dedicated box. If the application is complex and the database is often updated, it'd be a good idea to separate the database and the application server to improve performance. If the application is simple you can install the database in the same server. From your code you can connect to the database regardless its location."

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