SQLite

Source: Wikipedia, the free encyclopedia.
SQLite
Developer(s)D. Richard Hipp
Initial release17 August 2000;
23 years ago (2000-08-17)
Stable release3.45.3[1] Edit this on Wikidata (15 April 2024; 12 days ago (15 April 2024)) [±]
Repository
Written in
RDBMS (embedded)
LicensePublic domain[2]
Websitesqlite.org Edit this at Wikidata
SQLite Database File Format
Filename extension
.sqlite, .sqlite3, .db, .db3, .s3db, .sl3
Public Domain)
Websitewww.sqlite.org/fileformat2.html

SQLite (

C programming language. It is not a standalone app; rather, it is a library that software developers embed in their apps. As such, it belongs to the family of embedded databases. It is the most widely deployed database engine, as it is used by several of the top web browsers, operating systems, mobile phones, and other embedded systems.[7]

Many

type checking by default.[8][9] This means that one can, for example, insert a string into a column
defined as an integer.

History

IBM Informix database back-end. SQLite began as a Tcl extension.[11]

In August 2000, version 1.0 of SQLite was released, with storage based on

document-oriented databases.[12] In 2018, SQLite adopted a Code of Conduct based on the Rule of Saint Benedict which caused some controversy and was later renamed as a Code of Ethics.[13]

SQLite is one of four formats recommended for long-term storage of datasets approved for use by the Library of Congress.[14][15][16]

Design

SQLite was designed to allow the program to be operated without installing a database management system or requiring a

function calls, reducing latency in database operations; for simple queries with little concurrency, SQLite performance profits from avoiding the overhead of inter-process communication
.

Due to the serverless design, SQLite applications require less configuration than client–server databases. SQLite is called zero-conf[17] because it does not require service management (such as startup scripts) or access control based on GRANT and passwords. Access control is handled by means of file-system permissions given to the database file itself. Databases in client–server systems use file-system permissions that give access to the database files only to the daemon process, which handles its locks internally, allowing concurrent writes from several processes.

SQLite stores the whole database (definitions,

threads to access the same database concurrently. It implements this simple design by locking the database file during writing. Write access may fail with an error code, or it can be retried until a configurable timeout expires. SQLite read operations can be multitasked, though due to the serverless design, writes can only be performed sequentially. This concurrent access restriction does not apply to temporary tables, and it is relaxed in version 3.7 as write-ahead logging (WAL) enables concurrent reads and writes.[18] Since SQLite has to rely on file-system locks, it is not the preferred choice for write-intensive deployments.[19]

SQLite uses

type checking; the type of a value is dynamic and not strictly constrained by the schema (although the schema will trigger a conversion when storing, if such a conversion is potentially reversible). SQLite strives to follow Postel's rule.[22]

Features

SQLite implements most of the

views (however, it provides INSTEAD OF triggers that provide this functionality). Its support of ALTER TABLE statements is limited.[23]

SQLite uses an unusual

type to a column as in most SQL database systems, types are assigned to individual values; in language terms it is dynamically typed. Moreover, it is weakly typed in some of the same ways that Perl is: one can insert a string into an integer column (although SQLite will try to convert the string to an integer first, if the column's preferred type is integer). This adds flexibility to columns, especially when bound to a dynamically typed scripting language. However, the technique is not portable to other SQL products. A common criticism is that SQLite's type system lacks the data integrity mechanism provided by statically typed columns, although it can be emulated with constraints like CHECK(typeof(x)='integer').[10] Strict tables were added in version 3.37.1.[22]

Tables normally include a hidden rowid index column, which gives faster access.

strictly typed 64-bit signed integer and changing its behavior to be somewhat like an auto-incrementing column. Future[when?] versions of SQLite may include a command to introspect whether a column has behavior like that of rowid to differentiate these columns from weakly typed, non-autoincrementing Integer Primary Keys.[25][failed verification
]

Version 3.6.19 released on October 14, 2009 added support for foreign key constraints.[26][27]

Stored procedures are not supported; this is an explicit choice by the developers to favor simplicity, as the typical use case of SQLite is to be embedded inside a host application that can define its own procedures around the database.[28]

Full support for Unicode case-conversions can be enabled through an optional extension.[29]

SQLite version 3.7.4 first saw the addition of the FTS4 (

Common table expressions support was added to SQLite in version 3.8.3.[34]
3.8.11 added a newer search module called FTS5, the more radical (compared to FTS4) changes requiring a bump in version.

In 2015, with the json1 extension[35] and new subtype interfaces, SQLite version 3.9 introduced JSON content managing.

As of version 3.33.0, the maximum supported database size is 281 TB.[36]

Development and distribution

SQLite's code is hosted with

distributed version control system that uses SQLite as a local cache for its non-relational database format, and SQLite's SQL as an implementation language.[37][38]

SQLite is public domain, but not "open-contribution", with the website stating "the project does not accept patches from people who have not submitted an affidavit dedicating their contribution into the public domain."[39] Instead of a code of conduct, the founders have adopted a code of ethics based on the Rule of St. Benedict.[40]

A standalone command-line shell program called sqlite3[41] is provided in SQLite's distribution. It can be used to create a database, define tables, insert and change rows, run queries and manage an SQLite database file. It also serves as an example for writing applications that use the SQLite library.

SQLite uses automated regression testing prior to each release. Over 2 million tests[42] are run as part of a release's verification. Starting with the August 10, 2009 release of SQLite 3.6.17, SQLite releases have 100% branch test coverage, one of the components of code coverage. The tests and test harnesses are partially public-domain and partially proprietary.[42]

Notable uses

Operating systems

SQLite is included by default in:[11]

Middleware

  • ADO.NET adapter, initially developed by Robert Simpson, is maintained jointly with the SQLite developers since April 2010.[44]
  • ODBC driver has been developed and is maintained separately by Christian Werner.[45] Werner's ODBC driver is the recommended connection method for accessing SQLite from OpenOffice.org.[46]
  • COM (ActiveX) wrapper making SQLite accessible on Windows to scripted languages such as JScript and VBScript. This adds SQLite database capabilities to HTML Applications (HTA).[47]

Web browsers

Web application frameworks

Others

See also

References

Citations

  1. ^ "SQLite Release 3.45.3 On 2024-04-15". 15 April 2024. Retrieved 15 April 2024.
  2. ^ "SQLite Copyright". sqlite.org. Retrieved May 17, 2010.
  3. ^ "SQLite database file format media type at IANA". Internet Assigned Numbers Authority. IANA. Retrieved 2019-03-08.
  4. ^ "Why SQLite succeeded as a database — Richard Hipp, creator of SQLite". The Changelog. Episode 201. Event occurs at 00:17:25. How do I pronounce the name of the product? I say S-Q-L-ite, like a mineral.
  5. ^ D. Richard Hipp (presenter) (May 31, 2006). An Introduction to SQLite (video). Google Inc. Event occurs at 00:01:14. Retrieved March 23, 2010. [...] ess-kju-ellite [...]
  6. ^ D. Richard Hipp (presenter) (May 31, 2006). An Introduction to SQLite. Google Inc. Event occurs at 00:48:15. Retrieved March 23, 2010. [...] sequelite [...]
  7. ^ "Most Widely Deployed SQL Database Estimates". SQLite.org. Retrieved May 11, 2011.
  8. ISBN 978-1-59059-673-9
    . Retrieved 30 December 2014.
  9. ^ "STRICT Tables".
  10. ^
    ISBN 978-1-59059-673-9
    .
  11. ^ a b c "Well-Known Users Of SQLite". SQLite. Retrieved August 5, 2015.
  12. ^ "Interview: Richard Hipp on UnQL, a New Query Language for Document Databases". InfoQ. August 4, 2011. Retrieved October 5, 2011.
  13. ^ McCarthy, Kieren. "SQLite creator crucified after code of conduct warns devs to love God, and not kill, commit adultery, steal, curse..." www.theregister.com. Retrieved 2022-11-17.
  14. ^ "LoC Recommended Storage Format". www.sqlite.org. Retrieved 2020-04-09.
  15. ^ "SQLite, Version 3". www.loc.gov. 2017-03-28. Retrieved 2020-04-09.
  16. ^ "Recommended Formats Statement – datasets/databases". Library of Congress. Retrieved 2020-04-09.
  17. ^ "SQLite Is A Zero-Configuration Database". SQLite.org. Retrieved August 3, 2015.
  18. ^ "Write Ahead Logging in SQLite 3.7". SQLite.org. Retrieved September 3, 2011. WAL provides more concurrency as readers do not block writers and a writer does not block readers. Reading and writing can proceed concurrently.
  19. ^ "Appropriate Uses For SQLite". SQLite.org. Retrieved 2015-09-03.
  20. ^ "PGCon 2014: Clustering and VODKA". Lwn.net. Retrieved 2017-01-06.
  21. ^ "PGCon2014: SQLite: Protégé of PostgreSQL". Pgcon.org. 20 September 2015. Retrieved 2017-01-06.
  22. ^ a b "SQLite: StrictMode". Sqlite.org. Retrieved September 3, 2015.
  23. ^ "Release History of SQLite".
  24. ^ "SQL As Understood By SQLite". SQLite. Retrieved 21 May 2018. Searching for a record with a specific rowid, or for all records with rowids within a specified range is around twice as fast as a similar search made by specifying any other PRIMARY KEY or indexed value.
  25. ^ "SQLite: Check-in [2494132a]". www.sqlite.org. 2017-11-28. Add the "PRAGMA table_ipk(TABLE)" command for evaluation purposes.
  26. ISBN 978-1-934356-55-5
    . Sometimes you're forced to use a database brand that doesn't support foreign key constraints (for example MySQL's MyISAM storage engine or SQLite prior to version 3.6.19).
  27. ^ "SQLite Release 3.6.19 On 2009-10-14". sqlite.org.
  28. ^ Source: developers' comments on SQLite forum
  29. ^ "Case-insensitive matching of Unicode characters does not work". SQLite Frequently Asked Questions. Retrieved 2015-09-03.
  30. ^ "SQLite Release 3.7.4 On 2010-12-08". SQLite.org. December 8, 2010. Retrieved September 3, 2015.
  31. ^ "SQLite FTS3 and FTS4 Extensions". SQLite.org. Retrieved September 3, 2015.
  32. ^ "SQLite Release 3.8.2 On 2013-12-06". SQLite.org. December 6, 2013. Retrieved September 3, 2015.
  33. ^ "The WITHOUT ROWID Optimization". SQLite.org. Retrieved September 3, 2015.
  34. ^ "SQLite Release 3.8.3 On 2014-02-03". SQLite.org. February 3, 2014. Retrieved September 3, 2015.
  35. ^ "The JSON1 Extension". SQLite.org.
  36. ^ "Limits In SQLite". SQLite.org.
  37. ^ "Thoughts On The Design Of The Fossil DVCS". Fossil-scm.org. July 12, 2017. Retrieved October 14, 2022.
  38. ^ "Fossil: Fossil Performance". Fossil-scm.org. August 23, 2009. Retrieved September 12, 2009.
  39. ^ "SQLite Copyright". sqlite.org. Retrieved 2024-03-06.
  40. ^ "Code Of Ethics". sqlite.org. Retrieved 2024-03-06.
  41. ^ "Command Line Shell For SQLite". Sqlite.org. Retrieved October 14, 2022.
  42. ^ a b "How SQLite Is Tested". SQLite.org. Retrieved September 12, 2009.
  43. ^ "To use the version of SQLite that is installed with Windows". 20 October 2022.
  44. ^ "Home". System.Data.SQLite. 2016-12-30. Retrieved 2017-01-06.
  45. ^ "SQLite ODBC Driver". Ch-werner.de. 2016-12-01. Retrieved 2017-01-06.
  46. ^ "Using SQLite Database with OpenOffice.org : Version 2.0" (PDF). Documentation.openoffice.org. Retrieved 2017-01-06.
  47. ^ "sqlite — Sqlite Wrappers". SQLite.org. February 7, 2009. Retrieved February 7, 2009.
  48. ^ "sqlite3 WebAssembly & JavaScript Documentation Index". SQLite. Retrieved 2023-05-08.
  49. ^ "Location of Google Chrome history". www.foxtonforensics.com. 2020-10-06. Retrieved 2020-10-06.
  50. ^ "SQLite Manager :: Add-ons for Firefox". Addons.mozilla.org. 2015-02-28. Archived from the original on 2017-01-02. Retrieved 2017-01-06.
  51. ^ "SQLite Manager – Get this Extension for 🦊 Firefox (en-US)". Addons.mozilla.org. 2018-07-24. Retrieved 2018-10-05.
  52. ^ "SQLite Reader – Get this Extension for 🦊 Firefox (en-US)". Addons.mozilla.org. 2018-09-01. Retrieved 2018-10-05.
  53. ^ "Using SQL to find my best photo of a pelican according to Apple Photo". Simon Willison’s Weblog. Retrieved May 23, 2020.
  54. ^ "Audacity 3.0.0 Released". 17 March 2021. Retrieved March 17, 2021.
  55. ^ Hinegardner, Jeremy (August 28, 2007). "Skype client using SQLite?". sqlite-users (Mailing list). Archived from the original on 2007-11-17. Retrieved June 14, 2010.

Sources

External links

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