SQLite/Introduction

Rewrite/Reflow text for brevity and coherence. Design Unlike client–server database management systems, the SQLite engine has no standalone processes with which the application program communicates. Instead, the SQLite library is linked in and thus becomes an integral part of the application program. The library can also be called dynamically. The application program uses SQLite's functionality through simple function calls, which reduce latency in database access: function calls within a single process are more efficient than inter-process communication. SQLite stores the entire database (definitions, tables, indices, and the data itself) as a single cross-platform file on a host machine. It implements this simple design by locking the entire database file during writing. SQLite read operations can be multitasked, though writes can only be performed sequentially. Due to the server-less design, SQLite applications require less configuration than client-server databases. SQLite is called zero-conf SQLite Is A Zero-Configuration Database https://sqlite.org/zeroconf.html August 3, 2015 SQLite.org 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 which give access to the database files only to the daemon process. Another implication of the serverless design is that several processes may not be able to write to the database file. In server-based databases, several writers will all connect to the same daemon, which is able to handle its locks internally. SQLite on the other hand has to rely on file-system locks. It has less knowledge of the other processes that are accessing the database at the same time. Therefore, SQLite is not the preferred choice for write-intensive deployments. Appropriate Uses For SQLite https://sqlite.org/whentouse.html 2015-09-03 SQLite.org However, for simple queries with little concurrency, SQLite performance profits from avoiding the overhead of passing its data to another process. SQLite uses PostgreSQL as a reference platform. “What would PostgreSQL do” is used to make sense of the SQL standard.https://lwn.net/Articles/601144/ PGCon 2014: Clustering and VODKA Lwn.net 2017-01-06https://www.pgcon.org/2014/schedule/events/736.en.html PGCon2014: SQLite: Protégé of PostgreSQL Pgcon.org 2017-01-06 One major deviation is that, with the exception of primary keys, SQLite does not enforce 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. History D. Richard Hipp designed SQLite in the spring of 2000 while working for General Dynamics on contract with the United States Navy.Owens Michael The Definitive Guide to SQLite 2006 Apress 978-1-59059-673-9 10.1007/978-1-4302-0172-4_1 Hipp was designing software used aboard guided missile destroyers, which originally used HP-UX with an IBM Informix database back-end. SQLite began as a Tcl extension. The design goals of SQLite were to allow the program to be operated without installing a database management system or requiring a database administrator. Hipp based the syntax and semantics on those of PostgreSQL 6.5. In August 2000, version 1.0 of SQLite was released, with storage based on gdbm (GNU Database Manager). SQLite 2.0 replaced gdbm with a custom B-tree implementation, adding transaction capability. SQLite 3.0, partially funded by America Online, added internationalization, manifest typing, and other major improvements. In 2011 Hipp announced his plans to add a NoSQL interface (managing documents expressed in JSON) to SQLite databases and to develop UnQLite, an embeddable document-oriented database.http://www.infoq.com/news/2011/08/UnQL Interview: Richard Hipp on UnQL, a New Query Language for Document Databases InfoQ August 4, 2011 October 5, 2011. UnQLite was released as an independent database.UnQLite FAQ Features SQLite implements most of the SQL-92 standard for SQL but it lacks some features. For example, it partially provides triggers, and it cannot write to views (however it provides INSTEAD OF triggers that provide this functionality). While it provides complex queries, it still has limited ALTER TABLE function, as it cannot modify or delete columns. https://sqlite.org/omitted.html January 1, 2009 SQL Features That SQLite Does Not Implement SQLite.org October 14, 2009 SQLite uses an unusual type system for an SQL-compatible DBMS; instead of assigning a 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 in other products. The SQLite web site describes a "strict affinity" mode, but this feature has not yet been added. SQLite: StrictMode https://sqlite.org/src/wiki?name=StrictMode Sqlite.org September 3, 2015 However, it can be implemented with constraints like CHECK(typeof(x)='integer'). SQLite with full Unicode function is optional. Case-insensitive matching of Unicode characters does not work. https://sqlite.org/faq.html#q18 SQLite Frequently Asked Questions 2015-09-03 Several computer processes or threads may access the same database concurrently. Several read accesses can be satisfied in parallel. A write access can only be satisfied if no other accesses are currently being serviced. Otherwise, the write access fails with an error code (or can automatically be retried until a configurable timeout expires). This concurrent access situation would change when dealing with temporary tables. This restriction is relaxed in version 3.7 when write-ahead logging (WAL) is turned on enabling concurrent reads and writes. https://sqlite.org/wal.html Write Ahead Logging in SQLite 3.7 SQLite.org 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 SQLite version 3.7.4 first saw the addition of the FTS4 (full text search) module, which features enhancements over the older FTS3 module. SQLite Release 3.7.4 On 2010-12-08 https://sqlite.org/releaselog/3_7_4.html September 3, 2015 December 8, 2010 SQLite.org FTS4 allows users to perform full text searches on documents similar to how search engines search webpages. SQLite FTS3 and FTS4 Extensions https://sqlite.org/fts3.html September 3, 2015 SQLite.org Version 3.8.2 added support for creating tables without rowid, SQLite Release 3.8.2 On 2013-12-06 https://sqlite.org/releaselog/3_8_2.html September 3, 2015 December 6, 2013 SQLite.org which may provide space and performance improvements. The WITHOUT ROWID Optimization https://sqlite.org/withoutrowid.html September 3, 2015 SQLite.org Common table expressions support was added to SQLite in version 3.8.3. SQLite Release 3.8.3 On 2014-02-03 https://sqlite.org/releaselog/3_8_3.html September 3, 2015 February 3, 2014 SQLite.org In 2015, with the json1 extensionhttps://sqlite.org/json1.html and new subtype interfaces, SQLite version 3.9 introduced JSON content managing. Development and distribution SQLite's code is hosted with Fossil, a distributed version control system that is itself built upon an SQLite database. https://www.fossil-scm.org/index.html/doc/tip/www/stats.wiki Fossil: Fossil Performance Fossil-scm.org August 23, 2009 September 12, 2009 A standalone command-line program 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 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. https://sqlite.org/testing.html How SQLite Is Tested SQLite.org September 12, 2009 Notable users Adoption The browsers Google Chrome, Opera, Safari and the Android Browser all allow for storing information in, and retrieving it from, a SQLite database within the browser, using the Web SQL Database technology, although this is rapidly becoming deprecated (namely superseded by IndexedDB). Mozilla Firefox and Mozilla Thunderbird store a variety of configuration data (bookmarks, cookies, contacts etc.) in internally managed SQLite databases. There is a third-party add-on that uses the code supporting this functionality to provide a user interface for managing arbitrary SQLite databases. https://addons.mozilla.org/en-US/firefox/addon/sqlite-manager/ SQLite Manager :: Add-ons for Firefox Addons.mozilla.org 2015-02-28 2017-01-06 Various web application frameworks Adobe Systems uses SQLite as its file format in Adobe Photoshop Lightroom, a standard database in Adobe AIR, and internally within Adobe Reader. Well-Known Users Of SQLite https://sqlite.org/famous.html August 5, 2015 SQLite Evernote uses SQLite to store its local database repository in Windows. Skype https://www.mail-archive.com/sqlite-users%40sqlite.org/msg27326.html Skype client using SQLite? Mail-archive.com August 28, 2007 June 14, 2010 Applehttp://osxdaily.com/2012/07/12/list-download-history-mac-os-x/ Show Download History List of All Files Ever Downloaded Within Mac OS X Osxdaily.com 2012-07-12 2017-01-06 adopted it as an option in macOS's Core Data API from the original implementation in Mac OS X 10.4 onwards, and also for administration of videos and songs, and in iOS for storage of text messages on the iPhone. Windows 10https://msdn.microsoft.com/en-us/windows/uwp/data-access/sqlite-databases SQLite databases Msdn.microsoft.com 2016-09-19 2017-01-06 Programming language support A large number of programming languages provide bindings for SQLite, including: 20em AutoIthttps://www.autoitscript.com/autoit3/docs/libfunctions/SQLite%20Management.htm User Defined Functions Autoitscript.com 2017-01-06 various dialects of BASIC including FreeBASIC, PureBasic, RFO BASIC!, Visual Basic and Xojo C C# C++ Clipper//Harbour Curl D Elixir Emacs Lisphttps://github.com/pekingduck/emacs-sqlite3-api SQLite3 API for GNU Emacs 25+ github.com 2017-10-02 F#Ross McKinlay Colin Bull https://fsprojects.github.io/SQLProvider/ SQLProvider Fsprojects.github.io 2017-01-06 Go Haskell Haxe Java (on JVM and DVM) JavaScripthttp://code.google.com/p/v8-juice/wiki/JSPDO Google Code Archive - Long-term storage for Google Code Project Hosting Code.google.com 2017-01-06 Julia distributions of Lisp such as Common Lisp, newLisp, OpenLisp Transcript (on LiveCode) LabVIEW Lua MATLAB Nim Objective-C (on macOS and iOS) OCaml several flavours of Pascal including Free Pascal, Component Pascal and Delphi PerlAdam Kennedy https://metacpan.org/module/DBD::SQLite DBD::SQLite - Self-contained RDBMS in a DBI Driver Metacpan.org 2017-01-06 PHP Pike Pythonhttp://trac.edgewall.org/wiki/PySqlite PySqlite – The Trac Project Trac.edgewall.org 2015-12-31 2017-01-06 R Rackethttps://docs.racket-lang.org/continue/index.html#%28part._.Using_an_.S.Q.L_database%29 Continue: Web Applications in Racket - 15 Using an SQL database docs.racket-lang.org 2017-02-24 REBOL Rubyhttp://rubyforge.org/projects/sqlite-ruby Archived copy 2010-04-03 yes https://web.archive.org/web/20100417055245/http://rubyforge.org/projects/sqlite-ruby 2010-04-17 Scheme Smalltalk Swift (on macOS and iOS) Tcl Xojo References Citations 30em Sources Grant Allen Mike Owens November 5, 2010 The Definitive Guide to SQLite 2nd Apress 368 1-4302-3225-0 http://apress.com/book/view/1430232250 Jay A. Kreibich August 17, 2010 Using SQLite 1st O'Reilly Media 528 0-596-52118-9 http://oreilly.com/catalog/9780596521196 Rick F. van der Lans September 7, 2009 The SQL Guide to SQLite lulu.com 1st 542 0-557-07676-5 Chris Newman November 9, 2004 SQLite (Developer's Library) 1st Sams 336 0-672-32685-X http://www.informit.com/store/product.aspx?isbn=067232685X