SQLite is a lightweight, independent program library or database that is already embedded in many applications. It is in particular the absence of a client-server structure that characterizes this database system. Alternatives to SQLite worth mentioning are MySQL, MongoDB, and PostgreSQL.
What is SQLite?
SQLite is the most widespread and widely used database system in the world. The software, originally designed by D. Richard Hipp in 2000 for the US military, is now in the public domain and therefore copyright free. The name « SQLite » is made up of « SQL » (short for « Structured Query Language »), and « lite », a colloquial term for a lighter, less memory-intensive version.
This name is explained in particular by the fact that the SQLite relational database does not require additional server software, unlike other common databases. The reduced size of only a few hundred kilobytes as well as the storage of an entire database in a single file also contributed to the choice of the name.
SQLite is written in the C programming language, used in particular in many operating systems and programs such as Android, iOS or Windows Phone, Skype instant messaging as well as Google Chrome, Mozilla Firefox and Safari SQLite browsers. The respective data is stored in tables in the program library and can be viewed column by column. Integration into other programs is no problem via the C interface or an interface such as Ruby, PHP or Python.
With SQLite3 in Python, the programming language even has a integration module for SQLite. There is no need to install or configure the open source database system.
How does SQLite work?
SQLite does not require a long learning phase, but can be integrated directly into an application without the need for additional server software. This then receives full database functions automatically and without further tools. All tables, references, links and the like are grouped in a single compact filewhich can also be stored in main memory.
The use of a file in different systems is therefore very simple and it becomes possible to store any data in a table. These are then only converted when necessary, so that even switching from one system to another with a different byte order can be considered.
As a relational database management system, SQLite uses a two-key principle to identify entries in a table and relate different tables together. A primary key and a foreign key are used for this purpose.
- Primary key: it is a unique value that can be assigned to a specific row in the table.
- Foreign key: this is used to link multiple tables together.
These references allow considerably lighten the structure and make working with SQLite easier than other databases. These attributes also contributed to the global spread of the database system.
What types of data are possible in SQLite?
In SQLite, data can be stored in different formats. It also follows that a conversion is not necessarily required for further cross-system processing. The possible types of data that can be recorded and stored are:
- INTEGER: includes all integer values.
- REAL: includes approximate representations of a real number as a floating-point number or a floating-point number.
- TEXT: contains all plain text content.
- BLOB: short for Binary Large Object and contains binary values such as preview images or configuration files in XML format.
- NULL: null values can also be represented in SQLite.
This means that all common data types can be stored in SQLite.
How is data backed up in SQLite?
There are two ways to ensure that database consistency is maintained in SQLite:
- Rollback Journal: with this method, a temporary log of all the changes made is automatically created. This log contains the name of the affected database and the suffix “-journal”. In the event of problems with the database or certain files, it is thus possible to perform a rollback to return to a previous state.
- Write Ahead Log (WAL): in the case of a Write Ahead Log, all changes are recorded in a log file. Then, when the database is closed as expected, the data is permanently inserted into the database. You can also save them manually using a commit command. In parallel, an index is created in the Shared Memory (SHM) file.
What are the benefits of SQLite?
SQLite offers many advantages and has earned a good reputation among commercial application developers and private users. Among the arguments in favor of the relational system are the following points:
Scope
The low memory requirement is a big advantage of the database system. With only a few hundred kilobytes, a library takes up very little space, which of course has a positive effect on speed. This is where SQLite lives up to its name and proves to be a powerful solution for both large and small applications.
No additional software
SQLite works without any other server software and integrates easily and seamlessly. No other external program or package is needed. The server power that must be made available in this way is also transparent.
Versatility
Not only does SQLite support most SQL language commands, but its compatibility with a lot of common data warehouses is also a great advantage. It is no coincidence that the library is used in many applications like Facebook or WhatsApp, as well as in all common operating systems for desktop computers and mobile phones, browsers and many commercial programs. Since the exchange between two different systems is also possible without too many problems, many developers rely on the lightweight solution as the basis for their software.
Portability
The aspects mentioned above also result in SQLite files being very easy to back up and transport. Since there is no need to configure SQLite extensively and the respective files are independent of the server programs, it is possible to use it on different systems without problems.
Fault resistance
Unified data access, low resource consumption and independence from a server-client structure make SQLite a very secure option. Memory errors or issues due to lack of RAM also matter less here.
Public domain
SQLite is available without a license. Only some add-ons and support are chargeable.
What are the disadvantages of SQLite?
Despite its advantages, SQLite also has some disadvantages to consider if you plan to use the database system. These include the following in particular:
Restricted use
SQLite does not provide an option for multiple user accounts. This is what sets this solution apart from others. A connection of several clients is therefore not possible.
Growing need for space
Even though SQLite is actually a very lightweight solution, the needs increase as the database gets bigger. It can also have a negative impact on performance.
Flexibility
Admittedly, SQLite is an overall flexible solution, which is mainly due to its independence from external server structures. However, this also implies that no data requests can be made from the client. Moreover, it is not possible to process several connections at the same time, which can lead to delays.
What are the alternatives to the Program Library?
There are many alternatives to SQLite. In addition to the document-oriented NoSQL solution MongoDB and the relational PostgreSQL, MySQL in particular is a very widespread alternative, partly proprietary and partly open source. This option is also very user-friendly. To learn how to use this database system, see the Digital Guide’s MySQL tutorial.
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