Appropriate Uses For SQLite
SQLite is different from most other SQL database engines in that its primary design goal is to be simple:
Simple to administer
Simple to operate
Simple to embed in a larger program
Simple to maintain and customize
Many people like SQLite because it is small and fast. But those qualities are just happy accidents. Users also find that SQLite is very reliable. Reliability is a consequence of simplicity. With less complication, there is less to go wrong. So, yes, SQLite is small, fast, and reliable, but first and foremost, SQLite strives to be simple.
Simplicity in a database engine can be either a strength or a weakness, depending on what you are trying to do. In order to achieve simplicity, SQLite has had to sacrifice other characteristics that some people find useful, such as high concurrency, fine-grained access control, a rich set of built-in functions, stored procedures, esoteric SQL language features, XML and/or Java extensions, tera- or peta-byte scalability, and so forth. If you need some of these features and do not mind the added complexity that they bring, then SQLite is probably not the database for you. SQLite is not intended to be an enterprise database engine. It is not designed to compete with Oracle or PostgreSQL.
The basic rule of thumb for when it is appropriate to use SQLite is this: Use SQLite in situations where simplicity of administration, implementation, and maintenance are more important than the countless complex features that enterprise database engines provide. As it turns out, situations where simplicity is the better choice are more common than many people realize.
Another way to look at SQLite is this: SQLite is not designed to replace Oracle. It is designed to replace fopen().
Situations Where SQLite Works Well
Application File Format
SQLite has been used with great success as the on-disk file format for desktop applications such as financial analysis tools, CAD packages, record keeping programs, and so forth. The traditional File/Open operation does an sqlite3_open() and executes a BEGIN TRANSACTION to get exclusive access to the content. File/Save does a COMMIT followed by another BEGIN TRANSACTION. The use of transactions guarantees that updates to the application file are atomic, durable, isolated, and consistent.
Temporary triggers can be added to the database to record all changes into a (temporary) undo/redo log table. These changes can then be played back when the user presses the Undo and Redo buttons. Using this technique, an unlimited depth undo/redo implementation can be written in surprisingly little code.
Embedded devices and applications
Because an SQLite database requires little or no administration, SQLite is a good choice for devices or services that must work unattended and without human support. SQLite is a good fit for use in cellphones, PDAs, set-top boxes, and/or appliances. It also works well as an embedded database in downloadable consumer applications.
Websites
SQLite usually will work great as the database engine for low to medium traffic websites (which is to say, 99.9% of all websites). The amount of web traffic that SQLite can handle depends, of course, on how heavily the website uses its database. Generally speaking, any site that gets fewer than 100K hits/day should work fine with SQLite. The 100K hits/day figure is a conservative estimate, not a hard upper bound. SQLite has been demonstrated to work with 10 times that amount of traffic.
Replacement for ad hoc disk files
Many programs use fopen(), fread(), and fwrite() to create and manage files of data in home-grown formats. SQLite works particularly well as a replacement for these ad hoc data files.
Internal or temporary databases
For programs that have a lot of data that must be sifted and sorted in diverse ways, it is often easier and quicker to load the data into an in-memory SQLite database and use queries with joins and ORDER BY clauses to extract the data in the form and order needed rather than to try to code the same operations manually. Using an SQL database internally in this way also gives the program greater flexibility since new columns and indices can be added without having to recode every query.
责任编辑：小草
