SQLite Components

SQLite is a full-featured relational database manager.

SQLite software takes an unusual approach to database management, compared to offerings such as IBM’s DB2 and Microsoft’s SQL Server. SQLite does not have a separate database server program; instead, it becomes part of the application that uses the database. The software's highly efficient design implements most of the SQL-92 standard while avoiding the heavy use of computing resources usually encountered with database management software.

SQLite

SQLite is a free, open-source, relational database management system that uses the industry-standard Structured Query Language, or SQL. Though most database server systems involve gigabytes of software, SQLite fits its entire code base into a package of about 350KB, making it a popular choice for applications running on smartphones, tablets and other small systems. A consortium of hardware and software companies, including Oracle, Adobe and Nokia, oversees SQLite’s development.

Library

The main component in SQLite is its library, a file that becomes part of a larger software application. For example, if a programmer writes a game that uses a SQLite database, its library is added to the program files for the game in a process called “compiling.” The compiled program file contains the game and the SQLite library. When a player makes a high score, the game program passes information to the library, which writes the score into the database.

Database

SQLite stores its database information in a single file, one file per database. The file contains the tables, views and other structures normally present in a database, as well as supporting information. For example, the file contains indexes used to locate data in a database quickly. The maximum size of a SQLite database file is 140 terabytes, sufficient for nearly any imaginable use.

Auxiliary Files

SQLite maintains auxiliary files that keep track of the database’s state. These files reside in the same directory as the database file. One file, called a rollback journal, saves transactions in progress. If the computer experiences a power failure in the middle of a database update, and is subsequently restarted, SQLite uses the rollback journal to gracefully undo any half-finished transactions. Another file, called the write-ahead log or WAL, serves a similar purpose. A database may have a rollback journal or a WAL, but not both.

References

• SQLite: Features of SQLite

Resources

• SQLite: Download Page