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{{Short description|Database engine built by Microsoft}}
{{Use mdy dates|date=January 2019}}
{{Use American English|date=January 2019}}
{{about|JET Red used in [[Microsoft Access]]|the JET Blue [[ISAM]] implementation|Extensible Storage Engine}}
{{Infobox software
| name = Access Database Engine
| title = Access Database Engine
| other_names = {{ubl|ACE Database Engine|Office Access Connectivity Engine (ACE)|Microsoft JET Engine|Microsoft Jet Database Engine|Jet Red|Joint Engine Technology (JET)}}
| logo =
| screenshot =
| caption =
| developer = [[Microsoft]]
| released = {{Start date and age|1992}}
| discontinued =
| latest release version = ACE 16
| latest release date = 
| latest preview version =
| latest preview date =
| programming language =
| operating system = [[Microsoft Windows]]
| platform =
| genre = [[Database engine]]
| license =
}}
The '''Access Database Engine''' (also '''Office Access Connectivity Engine''' or '''ACE''' and formerly '''Microsoft Jet Database Engine''', ''Microsoft JET Engine'' or simply ''Jet'') is a [[database engine]] on which several [[Microsoft]] products have been built. The first version of Jet was developed in 1992, consisting of three [[Module (programming)|modules]] which could be used to manipulate a database.

JET stands for ''Joint Engine Technology''. [[Microsoft Access]] and [[Visual Basic]] use or have used Jet as their underlying database engine. However, it has been superseded for general use, first by [[Microsoft Desktop Engine]] (MSDE), then later by [[SQL Server Express]]. For larger database needs, Jet databases can be upgraded (or, in Microsoft parlance, "up-sized") to Microsoft's flagship SQL Server database product.

==Architecture==
{{Unreferenced section|July 2010|date=July 2010}}
Jet, being part of a [[relational database management system]] (RDBMS), allows the manipulation of [[relational database]]s.<ref>{{Cite web |title=What is an RDBMS (relational database management system)? {{!}} Definition from TechTarget |url=https://www.techtarget.com/searchdatamanagement/definition/RDBMS-relational-database-management-system |access-date=2024-06-20 |website=Data Management |language=en}}</ref> It offers a single [[interface (computer science)|interface]] that other software can use to access Microsoft databases and provides support for security, [[referential integrity]], [[transaction processing]], [[index (database)|index]]ing, [[record locking|record]] and page locking, and data replication. In later versions, the engine has been extended to run [[SQL]] queries, store character data in [[Unicode]] format, create [[View (database)|database views]] and allow bi-directional replication with Microsoft SQL Server.

[[File:Jet DLLs.svg|thumb|right|300px|Jet DLLs]]
There are three modules to Jet: One is the ''Native Jet ISAM Driver'', a [[Library (computer science)#Dynamic linking|dynamic link library]] (DLL) that can directly manipulate Microsoft Access database files (MDB) using a (random access) file system API. Another one of the modules contains the ''ISAM Drivers'', DLLs that allow access to a variety of [[Indexed Sequential Access Method]] ISAM databases, among them [[xBase]], [[Paradox (database)|Paradox]], [[Btrieve]] and [[FoxPro]], depending on the version of Jet. The final module is the ''Data Access Objects'' (DAO) DLL.<ref>{{Cite web |title=DAO, ODBC Connectivity {{!}} PDF {{!}} Microsoft Access {{!}} Databases |url=https://www.scribd.com/document/425948837/DAO-ODBC-Connectivity |access-date=2024-06-20 |website=Scribd |language=en}}</ref> [[Data Access Objects|DAO]] provides an [[API]] that allows programmers to access JET databases using any programming language.

===Locking===
Jet allows multiple users to access the database concurrently. To prevent that data from being corrupted or invalidated when multiple users try to edit the same record or page of the database, Jet employs a locking policy. Any single user can modify only those [[database record]]s (that is, items in the database) to which the user has applied a [[lock (computer science)|lock]], which gives exclusive access to the record until the lock is released. In Jet versions before version 4, a page locking model is used, and in Jet 4, a record locking model is employed. Microsoft databases are organized into data "pages", which are fixed-length (2 [[kilobyte|kB]] before Jet 4, 4 kB in Jet 4) data structures. Data is stored in "records" of variable length that may take up less or more than one page. The page locking model works by locking the pages, instead of individual records, which though less resource-intensive also means that when a user locks one record, all other records on the same page are collaterally locked. As a result, no other user can access the collaterally locked records, even though no user is accessing them and there is no need for them to be locked. In Jet 4, the record locking model eliminates collateral locks, so that every record that is not in use is available.

There are two mechanisms that Microsoft uses for [[Concurrency control|locking]]: ''pessimistic locking'', and ''optimistic locking''. With pessimistic locking, the record or page is locked immediately when the lock is requested, while with optimistic locking, the locking is delayed until the edited record is saved. Conflicts are less likely to occur with optimistic locking, since the record is locked only for a short period of time. However, with optimistic locking one cannot be certain that the update will succeed because another user could lock the record first. With pessimistic locking, the update is guaranteed to succeed once the lock is obtained. Other users must wait until the lock is released in order to make their changes. Lock conflicts, which either require the user to wait, or cause the request to fail (usually after a timeout) are more common with pessimistic locking.

===Transaction processing===
Jet supports [[transaction processing]] for database systems that have this capability ([[Open Database Connectivity|ODBC]] systems have one-level transaction processing, while several ISAM systems like Paradox do not support transaction processing). A transaction is a series of operations performed on a database that must be done together — this is known as [[atomicity (database systems)|atomicity]] and is one of the [[ACID]] (Atomicity, Consistency, Isolation, and Durability), concepts considered to be the key transaction processing features of a [[database management system]]. For transaction processing to work (until Jet 3.0), the programmer needed to begin the transaction manually, perform the operations needed to be performed in the transaction, and then commit (save) the transaction. Until the transaction is committed, changes are made only in memory and not actually written to disk.{{Ref|TransactionMemory}} Transactions have a number of advantages over independent database updates. One of the main advantages is that transactions can be abandoned if a problem occurs during the transaction. This is called rolling back the transaction, or just rollback, and it restores the state of the database records to precisely the state before the transaction began. Transactions also permit the state of the database to remain consistent if a system failure occurs in the middle of a sequence of updates required to be atomic. There is no chance that only some of the updates will end up written to the database; either all will succeed, or the changes will be discarded when the database system restarts. With ODBC's in-memory policy, transactions also allow for many updates to a record to occur entirely within memory, with only one expensive disk write at the end.

Implicit transactions were supported in Jet 3.0. These are transactions that are started automatically after the last transaction was committed to the database. Implicit transactions in Jet occurred when an [[SQL]] [[Data Manipulation Language|DML]] statement was issued. However, it was found that this had a negative performance impact in 32-bit Windows (Windows 95, Windows 98), so in Jet 3.5 Microsoft removed implicit transactions when SQL DML statements were made.

===Data integrity===
Jet enforces [[entity integrity]] and [[referential integrity]]. Jet will by default prevent any change to a record that breaks referential integrity, but Jet databases can instead use [[propagation constraint]]s (cascading updates and cascading deletes) to maintain referential integrity.

Jet also supports "business rules" (also known as "constraints"), or rules that apply to any column to enforce what data might be placed into the table or [[column (database)|column]]. For example, a rule might be applied that does not allow a date to be entered into a date_logged column that is earlier than the current date and time, or a rule might be applied that forces people to enter a positive value into a numeric only field.

===Security===
Access to Jet databases is done on a per user-level. The user information is kept in a separate system database, and access is controlled on each object in the system (for instance by table or by query). In Jet 4, Microsoft implemented functionality that allows database administrators to set security via the SQL commands CREATE, ADD, ALTER, DROP USER and DROP GROUP. These commands are a subset of ANSI SQL 92 standard, and they also apply to the GRANT/REVOKE commands.<ref name='Jet4Features'>{{cite web|url=http://support.microsoft.com/kb/275561/en |title=Description of the new features that are included in Microsoft Jet 4.0 |access-date=2008-06-19 |publisher=Microsoft |last=MS KB article 275561 |date=2007-01-29 }}</ref> When Jet 2 was released, security could also be set programmatically through [[Data Access Objects|DAO]].

===Queries===
Queries are the mechanisms that Jet uses to retrieve data from the database. They can be defined in [[Microsoft QBE]] (Query By Example), through the Microsoft Access SQL Window or through Access Basic's Data Access Objects (DAO) language. These are then converted to a SQL [[Select (SQL)|SELECT]] statement. The query is then [[wikt:compile|compile]]d — this involves parsing the query (involves syntax checking and determining the columns to query in the database table), then converting into an internal Jet query object format, which is then [[Tokenization (lexical analysis)|tokenized]] and organized into a tree-like structure. In Jet 3.0 onward these are then optimized using the [[Microsoft Rushmore]] query optimization technology. The query is then executed and the results passed back to the application or user who requested the data.

Jet passes the data retrieved for the query in a [[dynaset]]. This is a set of data that is linked dynamically back to the database. Instead of having the query result stored in a temporary table, where the data cannot be updated directly by the user, the dynaset allows the user to view and update the data contained in the dynaset. Thus, if a university lecturer queries all students who received a distinction in their assignment and finds an error in that student's record, the user would only need to update the data in the dynaset, which would automatically update the student's database record without the need for the user to send a specific update query after storing the query results in a temporary table.

==History==
{| class="wikitable floatright" style="width:430px; float: right; background: white; margin-left: 10px; margin-right: 10px; margin-top: 5px; margin-bottom: 5px;"
|- VALIGN=TOP
! Jet version
! Jet engine
! DLL file name
! Supported database versions
|-
| align=left | 1.0
| {{dunno}}
| {{dunno}}
| 1.0
|-
| align=left | 1.1
| 1.10.0001
| align=left | MSAJT110.DLL
| {{hlist|1.0 | 1.1}}
|-
| align=left | 2.0
| 2.00.0000
| align=left | MSAJT200.DLL
| {{hlist|1.0 | 1.1 | 2.0}}
|-
| align=left | 2.5
| 2.50.1606
| align=left | MSAJT200.DLL
| {{hlist|1.0 | 1.1 | 2.0}}
|-
| align=left | 3.0
| 3.0.0.2118
| align=left | MSJT3032.DLL
| {{hlist|1.0 | 1.1 | 2.0 | 3.0}}
|-
| align=left | 3.5
| 3.51.3328.0
| align=left | MSJET35.DLL
| {{hlist|1.0 | 1.1 | 2.0 | 3.X}}
|-
| align=left | 4.0 SP8
| 4.0.8015.0
| align=left | MSJET40.DLL
| {{hlist|1.0 | 1.1 | 2.0 | 3.X | 4.0}}
|-
| align=left | ACE 12
| 12.0.xxxx.xxxx
| align=left | ACECORE.DLL
| {{hlist|1.0 | 1.1 | 2.0 | 3.X | 4.0 | ACE}}
|-
| align=left | ACE 14
| 14.0.xxxx.xxxx
| align=left | ACECORE.DLL
| {{hlist|3.X | 4.0 | ACE}}
|-
| align=left | ACE 15
| 15.0.xxxx.xxxx
| align=left | ACECORE.DLL
| {{hlist|4.0 | ACE}}
|-
| align=left | ACE 16
| 16.0.xxxx.xxxx
| align=left | ACECORE.DLL
| {{hlist|4.0 | ACE}}
|-
| style="text-align:left;" colspan="4"| <div style="font-size: 75%">Sources:
* https://web.archive.org/web/20150403002438/http://support.microsoft.com/en-us/kb/178880 
* https://web.archive.org/web/20150403002436/http://support.microsoft.com/en-us/kb/282010 
* https://web.archive.org/web/20141216193756/https://support.microsoft.com/kb/239114/</div>
|}

{| class="wikitable floatright" style="width:430px; float: right; background: white; margin-left: 10px; margin-right: 10px; margin-top: 5px; margin-bottom: 5px;"
|-4
! align=center | '''Application/Version'''
! align=center | '''Jet version'''
|-
| [[Microsoft Access]] 1.0
| align=left | 1.0
|-
| Microsoft Access 1.1
| 1.1
|-
| Microsoft Access 2.0
| 2.0
|-
| Microsoft Access 2.0 Service Pack
| 2.5
|-
| {{hlist|Microsoft Access 95 | [[Microsoft Excel|Excel]] 95}}
| 3.0
|-
| {{hlist|Microsoft Access 97 | Excel 97 | [[Microsoft PowerPoint|PowerPoint]] 97 | [[Microsoft Word|Word]] 97}}
| 3.5
|-
| Microsoft Access 2000
| 4.0 SP1
|-
| Microsoft Access 2002
| <ref>The Access 2002 setup program only updated system files on certain versions of Windows and to a certain level.</ref>
|-
| Microsoft Access 2003
| <ref>Access 2003 relied on the Jet engine component of the operating system for its data storage and query processing.</ref>
|-
| Microsoft Access 2007
| ACE 12
|-
| Microsoft Access 2010
| ACE 14
|-
| Microsoft Access 2013
| ACE 15
|-
| Microsoft Access 2016
| ACE 16
|-
| [[Visual Basic]] 3.0
| 1.1
|-
| Visual Basic Compatibility Layer
| 2.0
|-
| Visual Basic 4.0 16-bit
| 2.5
|-
| Visual Basic 4.0 32-bit
| 3.0
|-
| Visual Basic 5.0
| 3.5
|-
| [[Visual C Plus Plus|Visual C++]] 4.X
| 3.0
|-
| Visual C++ 5.0
| 3.5
|-
| {{hlist|[[Microsoft Project]] 4.1 | Project 95}}
| 3.0
|-
| [[Internet Information Services|Internet Information Server]] 3.0
| 3.5
|-
| [[Microsoft SQL Server|SQL Server]] 7.0
| 4.0
|-
| colspan="2" style="text-align:center;"| '''Redistributable installers'''
|-
| Jet 3.51 web download
| 3.5+
|-
| [[Microsoft Data Access Components|MDAC]] 2.1
| 4.0 SP1
|-
| MDAC 2.5
| 4.0 SP3 to SP6+
|-
| Jet 4.0
| 4.0 SP3 to SP8
|-
| 2007 Office System Driver
| ACE 12
|-
| Microsoft Access Database Engine 2010
| ACE 14
|-
| [https://www.microsoft.com/en-us/download/details.aspx?id=39358 Microsoft Access Database Engine 2013]
| ACE 15
|-
| [https://www.microsoft.com/en-us/download/details.aspx?id=54920 Microsoft Access Database Engine 2016]
| ACE 16
|-
| colspan="2" style="text-align:center;"| '''Operating systems'''
|-
| [[Windows Me]]
| 4.0 SP3
|-
| [[Windows 2000]]
| 4.0 SP3
|-
| [[Windows XP]]
| 4.0 SP5+
|-
| [[Windows Server 2003]]
| 4.0 SP6+
|-
| [[Windows Vista]]
| 4.0 SP8+
|-
| [[Windows Server 2008]]
| 4.0 SP8+
|-
| [[Windows 7]]
| 4.0 SP8+
|-
| style="text-align:left;" colspan="2"| <div style="font-size: 75%">Sources:
* [https://technet.microsoft.com/en-us/library/cc966378.aspx Microsoft Jet Database Engine Programmer's Guide - Introduction]
* [https://web.archive.org/web/20110524014114/http://support.microsoft.com/kb/178880/en INFO: Identifying the Jet Database Engine Components]
* [https://web.archive.org/web/20110604163201/http://support.microsoft.com/kb/231943/en Microsoft Data Access Components (MDAC) release history]
* [https://web.archive.org/web/20110604163211/http://support.microsoft.com/kb/842279/en Release manifest for MDAC 2.1 (2.1.1.3711.11) (GA)]
* [http://support.microsoft.com/kb/271908/en INFO: MDAC Version 2.6 and Later Do Not Contain Jet or Desktop ODBC Drivers]
* [https://support.microsoft.com/en-us/help/842176/release-manifest-for-mdac-2-5-service-pack-3-2-53-6200-2 Release manifest for MDAC 2.5 Service Pack 3 (2.53.6200.2)]
* [http://groups.google.co.uk/group/microsoft.public.access.gettingstarted/msg/84584fde3ef99112?hl=en Wrong Autonumber]{{Unreliable source?|reason=newsgroup posts are WP:RSSELF|date=March 2019}}
* [https://web.archive.org/web/20110524060440/http://support.microsoft.com/kb/239114/en How to obtain the latest service pack for the Microsoft Jet 4.0 Database Engine]
</div>
|}
Jet originally started in 1992 as an underlying data access technology that came from a Microsoft internal database product development project, code-named Cirrus. Cirrus was developed from a pre-release version of Visual Basic code and was used as the database engine of [[Microsoft Access]]. Tony Goodhew, who worked for Microsoft at the time, says
<blockquote>"It would be reasonably accurate to say that up until that stage Jet was more the name of the team that was assigned to work on the DB engine modules of Access rather than a component team. For VB [Visual Basic] 3.0 they basically had to tear it out of Access and graft it onto VB. That's why they've had all those Jet/ODBC problems in VB 3.0."
</blockquote>
Jet became more componentized when Access 2.0 was released because the Access ODBC developers used parts of the Jet code to produce the ODBC driver. A retrofit was provided that allowed Visual Basic 3.0 users to use the updated Jet issued in Access 2.0.<ref name=Goodhew1996-11>{{cite web |title=Jet Engine: History | last=Goodhew |first=Tony |date=November 1996 |url=http://www.avdf.com/nov96/acc_jet.html |archive-url=https://web.archive.org/web/20170808093446/http://www.avdf.com/nov96/acc_jet.html |archive-date=2017-08-08 |access-date=2020-03-28}}</ref>

Jet 2.0 was released as several [[Library (computer science)#Dynamic linking|dynamic linked libraries]] (DLL's) that were utilized by [[application software]], such as Microsoft's Access database. DLL's in [[Microsoft Windows|Windows]] are "libraries" of common code that can be used by more than one application—by keeping code that more than one application uses under a common library which each of these applications can use independently code maintenance is reduced and the functionality of applications increases, with less development effort. Jet 2.0 comprised three DLL's: the Jet DLL, the [[Data Access Objects]] (DAO) DLL and several external ISAM DLL's. The Jet DLL determined what sort of database it was accessing, and how to perform what was requested of it. If the data source was an MDB file (a Microsoft Access format) then it would directly read and write the data to the file. If the data source was external, then it would call on the correct ODBC driver to perform its request. The DAO DLL was a component that programmers could use to interface with the Jet engine, and was mainly used by Visual Basic and Access Basic programmers. The ISAM DLL's were a set of modules that allowed Jet to access three ISAM based databases: xBase, Paradox and Btrieve.{{Ref|MicrosoftJet2Overview}} Jet 2.0 was replaced with Jet 2.1, which used the same database structure but different locking strategies, making it incompatible with Jet 2.0.

Jet 3.0 included many enhancements, including a new [[index (database)|index]] structure that reduced storage size and the time that was taken to create indices that were highly duplicated, the removal of read [[lock (database)|locks]] on index pages, a new mechanism for page reuse, a new compacting method for which compacting the database resulted in the indices being stored in a clustered-index format, a new page allocation mechanism to improve Jet's read-ahead capabilities, improved delete operations that sped up processing, [[Thread (computer science)|multi-threading]] (three threads were used to perform read ahead, write behind, and cache maintenance), implicit transactions (users did not have to instruct the engine to start manually and commit transactions to the database), a new sort engine, long values (such as memos or binary data types) were stored in separate tables, and dynamic buffering (whereby Jet's cache was dynamically allocated at start up and had no limit and which changed from a [[fIFO (computing and electronics)|first in, first out]] (FIFO) buffer replacement policy to a [[least recently used]] (LRU) buffer replacement policy).<ref name='Jet3Features'>{{cite web|url=http://support.microsoft.com/kb/137039/en |title=New Features in Microsoft Jet Version 3.0 |access-date=2008-06-19 |publisher=Microsoft |last=MS KB article 137039 |date=2003-12-03 }}</ref> Jet 3.0 also allowed for database replication.
Jet 3.0 was replaced by Jet 3.5, which uses the same database structure, but different locking strategies, making it incompatible with Jet 3.0.

Jet 4.0 gained numerous additional features and enhancements.<ref name="Jet4Features"/>

* [[Unicode]] character storage support, along with an [[Windows NT|NT]] sorting method that was also implemented in the [[Windows 95]] version;
* Changes to data types to be more like [[Microsoft SQL Server|SQL Server]]'s (LongText or Memo; Binary; LongBinary; Date/Time; Real; Float4; IEEESingle; Double; Byte or Tinyint; Integer or Integer synonyms Smallint, Integer2, and Short; LongInteger or LongInteger synonyms Int, Integer, and Counter; Currency or Money; Boolean and GUID); a new decimal data type
* Memo fields could now be indexed
* Compressible data types
* [[SQL]] enhancements to make Jet conform more closely to [[ANSI]] [[SQL-92]]
* Finer grained security; views support; procedure support
* Invocation and termination (committing or rolling back) of transactions
* Enhanced table creation and modification
* [[Referential integrity]] support
* Connection control (connected users remain connected, but once disconnected they cannot reconnect, and new connections cannot be made. This is useful for database administrators to gain control of the database)
* A user list, which allows administrators to determine who is connected to the database
* Record-level locking (previous versions only supported page-locking)
* Bi-directional replication with MS SQL Server.

Microsoft Access versions from Access 2000 to Access 2010 included an "Upsizing Wizard" which could "[[upsizing (database)|upsize]]" (upgrade) a Jet database to "an equivalent database on SQL Server with the same table structure, data, and many other attributes of the original database". Reports, queries, macros and security were not handled by this tool, meaning that some manual modifications might have been needed if the application was heavily reliant on these Jet features.<ref name="upsize">''Microsoft'', "Microsoft Access 2000 Data Engine Options", white paper.</ref>

A standalone version of the Jet 4 database engine was a component of [[Microsoft Data Access Components]] (MDAC), and was included in every version of Windows from Windows 2000 on.<ref>{{cite web|url=http://support.microsoft.com/kb/239114/en |title=How to obtain the latest service pack for the Microsoft Jet 4.0 Database Engine |access-date=2010-01-02 |publisher=Microsoft |last=MS KB article 239114 |date=2008-05-29 }}</ref> The Jet database engine was only [[32-bit]] and did not run natively under [[64-bit]] versions of Windows. This meant that native 64-bit applications (such as the 64-bit versions of SQL Server) could not access data stored in MDB files through ODBC, [[OLE DB]], or any other means, except through intermediate 32-bit software (running in [[WoW64]]) that acted as a proxy for the 64-bit client.<ref>{{cite web | url = http://gorm-braarvig.blogspot.com/2005/11/access-database-from-sql-200564.html | title = Access database from SQL 2005/64 | author = Gorm Braarvig | access-date = 2007-06-18}}</ref>

With version 2007 onward, Access includes an Office-specific version of Jet, initially called the ''Office Access Connectivity Engine'' (ACE), but which is now called the ''Access Database Engine'' (However MS-Access consultants and VBA developers who specialize in MS-Access are more likely to refer to it as "the ACE Database Engine").{{Citation needed|date=September 2018}} This engine was backward-compatible with previous versions of the Jet engine, so it could read and write (.mdb) files from earlier Access versions. It introduced a new default file format, (.accdb), that brought several improvements to Access, including complex data types such as multi-value fields, the attachment data type and history tracking in memo fields. It also brought security changes and encryption improvements and enabled integration with Microsoft [[Windows SharePoint Services]] 3.0 and [[Microsoft Office Outlook]] 2007.<ref name='future'>{{cite web |url=http://msdn.microsoft.com/en-us/library/cc811599.aspx |title=Developing Access 2007 Solutions with Native C or C++ |first=Aleksandar |last=Jakšić |publisher=Microsoft Corporation |date=August 2008|access-date=2008-08-26 }}</ref><ref>Andy Baron, [http://msdn.microsoft.com/en-us/library/bb188204(SQL.90).aspx Optimizing Microsoft Office Access Applications Linked to SQL Server], November 2006.</ref><ref>Microsoft, [http://office.microsoft.com/en-us/access/HA100678311033.aspx New features of the Access 2007 file format] {{webarchive|url=https://web.archive.org/web/20091227213151/http://office.microsoft.com/en-us/access/HA100678311033.aspx |date=2009-12-27 }}.</ref> It can be obtained separately.<ref>[https://web.archive.org/web/20081221132443/http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=7554f536-8c28-4598-9b72-ef94e038c891 2007 Office System Driver: Data Connectivity Components]</ref>

The engine in Microsoft Access 2010 discontinued support for Access 1.0, Access 2.0, Lotus 1-2-3 and Paradox files.<ref>Microsoft, [http://office.microsoft.com/en-gb/access-help/discontinued-features-and-modified-functionality-in-access-2010-HA101806473.aspx Discontinued features and modified functionality in Access 2010].</ref> A 64-bit version of Access 2010 and its ACE Driver/Provider was introduced, which in essence provides a 64-bit version of Jet. The driver is not part of the Windows operating system, but is available as a redistributable.<ref>{{cite web | url = http://docs.microsoft.com/en-us/archive/blogs/psssql/how-to-get-a-x64-version-of-jet | title = How to get a x64 version of Jet? | author = Adam W. Saxton, Microsoft SQL Server Escalation Services |date=2010-01-21| access-date = 2021-10-29}}</ref><ref>{{cite web|url=http://www.microsoft.com/en-us/download/details.aspx?id=13255 |title=Microsoft Access Database Engine 2010 Redistributable |archiveurl=https://web.archive.org/web/20100907015006/http://www.microsoft.com/downloads/details.aspx?familyid=C06B8369-60DD-4B64-A44B-84B371EDE16D&displaylang=en |archivedate=2010-09-07}}</ref>

The engine in Microsoft Access 2013 discontinued support for Access 95, Access 97 and xBase files, and it also discontinued support for replication.<ref>Microsoft, [http://office.microsoft.com/en-us/access-help/discontinued-features-and-modified-functionality-in-access-2013-HA102749226.aspx Discontinued features and modified functionality in Access 2013].</ref>

Version 1608 of Microsoft Access 2016 restored support for xBase files,<ref>Microsoft, [https://blogs.office.com/en-us/2016/09/07/back-by-popular-demand-dbase-file-support-in-access/ Back by popular demand—dBASE file support in Access]</ref> and Version 1703 introduced a Large Number data type.<ref>Microsoft,
[https://support.office.com/en-gb/article/What-s-new-in-Access-2016-76454345-f85d-47af-ace1-98a456cb3496 What's New in Access 2016]</ref>

From a data access technology standpoint, Jet is considered a deprecated technology by Microsoft,<ref name=roadmap>{{cite web |url=http://msdn.microsoft.com/en-us/library/ms810810.aspx |title=Data Access Technologies Road Map |last1=Shirolkar |first1=Prash |last2=Henry |first2=Alyssa |last3=Pepitone |first3=Stephen |last4=Bunch |first4=Acey J. |publisher=Microsoft Corporation |date=January 2008|access-date=2008-06-19 }}</ref> but Microsoft continues to support ACE as part of Microsoft Access.

==Compatibility==
Microsoft provides the JET drivers for Microsoft Windows only and third party software support for JET databases is almost exclusively found on Windows. However, there are [[Open-source software|open source]] projects that enable working with JET databases on other platforms including [[Linux]]. Notably, [[MDB Tools]] and its much extended Java port named [http://jackcess.sourceforge.net/ Jackcess] as well as [https://ucanaccess.sourceforge.net/site.html UCanAccess].

==See also==
*[[SQL Server Compact]]

==References==
{{Reflist}}

==Further reading==
{{Wikibooks|JET Database}}
* [https://books.google.com/books?id=pMhvo3CIeTkC Microsoft Jet Database Engine Programmer's Guide], Microsoft, 1995
* Library of Congress, [https://www.loc.gov/preservation/digital/formats/fdd/fdd000462.shtml Microsoft Access MDB File Format Family]
* Library of Congress, [https://www.loc.gov/preservation/digital/formats/fdd/fdd000463.shtml Microsoft Access ACCDB File Format Family]

{{Microsoft development tools}}
{{Microsoft APIs}}

[[Category:Database engines]]
[[Category:Microsoft database software]]
[[Category:Proprietary database management systems]]

Access Database Engine - Revision history

imported>R'n'B: Disambiguating links to Tokenization (link changed to Tokenization (lexical analysis)) using DisamAssist.