<s>
The	O
Access	B-Application
Database	I-Application
Engine	I-Application
(	O
also	O
Office	B-Application
Access	I-Application
Connectivity	O
Engine	O
or	O
ACE	O
and	O
formerly	O
Microsoft	B-Application
Jet	I-Application
Database	I-Application
Engine	I-Application
,	O
Microsoft	B-Application
JET	I-Application
Engine	O
or	O
simply	O
Jet	B-Application
)	O
is	O
a	O
database	B-General_Concept
engine	I-General_Concept
on	O
which	O
several	O
Microsoft	O
products	O
have	O
been	O
built	O
.	O
</s>
<s>
The	O
first	O
version	O
of	O
Jet	B-Application
was	O
developed	O
in	O
1992	O
,	O
consisting	O
of	O
three	O
modules	B-Architecture
which	O
could	O
be	O
used	O
to	O
manipulate	O
a	O
database	O
.	O
</s>
<s>
JET	B-Application
stands	O
for	O
Joint	B-Application
Engine	I-Application
Technology	I-Application
.	O
</s>
<s>
Microsoft	B-Application
Access	I-Application
and	O
Visual	B-Language
Basic	I-Language
use	O
or	O
have	O
used	O
Jet	B-Application
as	O
their	O
underlying	O
database	B-General_Concept
engine	I-General_Concept
.	O
</s>
<s>
However	O
,	O
it	O
has	O
been	O
superseded	O
for	O
general	O
use	O
,	O
first	O
by	O
Microsoft	B-Application
Desktop	I-Application
Engine	I-Application
(	O
MSDE	B-Application
)	O
,	O
then	O
later	O
by	O
SQL	B-Application
Server	I-Application
Express	I-Application
.	O
</s>
<s>
For	O
larger	O
database	O
needs	O
,	O
Jet	B-Application
databases	I-Application
can	O
be	O
upgraded	O
(	O
or	O
,	O
in	O
Microsoft	O
parlance	O
,	O
"	O
up-sized	O
"	O
)	O
to	O
Microsoft	O
's	O
flagship	O
SQL	B-Application
Server	I-Application
database	O
product	O
.	O
</s>
<s>
A	O
five	O
billion	O
record	B-Operating_System
MS	O
Jet	B-Application
(	O
Red	O
)	O
database	O
with	O
compression	O
and	O
encryption	O
turned	O
on	O
requires	O
about	O
one	O
terabyte	O
of	O
disk	O
storage	O
space	O
.	O
</s>
<s>
Jet	B-Application
,	O
being	O
part	O
of	O
a	O
relational	B-Application
database	I-Application
management	I-Application
system	I-Application
(	O
RDBMS	O
)	O
,	O
allows	O
the	O
manipulation	O
of	O
relational	B-Application
databases	I-Application
.	O
</s>
<s>
It	O
offers	O
a	O
single	O
interface	B-Application
that	O
other	O
software	O
can	O
use	O
to	O
access	O
Microsoft	O
databases	B-Application
and	O
provides	O
support	O
for	O
security	O
,	O
referential	B-General_Concept
integrity	I-General_Concept
,	O
transaction	B-General_Concept
processing	I-General_Concept
,	O
indexing	O
,	O
record	B-Operating_System
and	O
page	O
locking	B-Operating_System
,	O
and	O
data	O
replication	O
.	O
</s>
<s>
In	O
later	O
versions	O
,	O
the	O
engine	O
has	O
been	O
extended	O
to	O
run	O
SQL	B-Language
queries	I-Language
,	O
store	O
character	O
data	O
in	O
Unicode	O
format	O
,	O
create	O
database	B-Language
views	I-Language
and	O
allow	O
bi-directional	O
replication	O
with	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
.	O
</s>
<s>
There	O
are	O
three	O
modules	B-Architecture
to	O
Jet	B-Application
:	O
One	O
is	O
the	O
Native	O
Jet	B-Application
ISAM	B-Application
Driver	O
,	O
a	O
dynamic	O
link	O
library	O
(	O
DLL	O
)	O
that	O
can	O
directly	O
manipulate	O
Microsoft	B-Application
Access	I-Application
database	O
files	O
(	O
MDB	O
)	O
using	O
a	O
(	O
random	O
access	O
)	O
file	O
system	O
API	B-General_Concept
.	O
</s>
<s>
Another	O
one	O
of	O
the	O
modules	B-Architecture
contains	O
the	O
ISAM	B-Application
Drivers	O
,	O
DLLs	O
that	O
allow	O
access	O
to	O
a	O
variety	O
of	O
Indexed	B-Application
Sequential	I-Application
Access	I-Application
Method	I-Application
ISAM	B-Application
databases	B-Application
,	O
among	O
them	O
xBase	B-Language
,	O
Paradox	B-Application
,	O
Btrieve	B-Application
and	O
FoxPro	B-Application
,	O
depending	O
on	O
the	O
version	O
of	O
Jet	B-Application
.	O
</s>
<s>
The	O
final	O
module	B-Architecture
is	O
the	O
Data	B-Library
Access	I-Library
Objects	I-Library
(	O
DAO	B-Library
)	O
DLL	O
.	O
</s>
<s>
DAO	B-Library
provides	O
an	O
API	B-General_Concept
that	O
allows	O
programmers	O
to	O
access	O
JET	B-Application
databases	I-Application
using	O
any	O
programming	O
language	O
.	O
</s>
<s>
Jet	B-Application
allows	O
multiple	O
users	O
to	O
access	O
the	O
database	O
concurrently	O
.	O
</s>
<s>
To	O
prevent	O
that	O
data	O
from	O
being	O
corrupted	O
or	O
invalidated	O
when	O
multiple	O
users	O
try	O
to	O
edit	O
the	O
same	O
record	B-Operating_System
or	O
page	O
of	O
the	O
database	O
,	O
Jet	B-Application
employs	O
a	O
locking	B-Operating_System
policy	O
.	O
</s>
<s>
Any	O
single	O
user	O
can	O
modify	O
only	O
those	O
database	B-Application
records	I-Application
(	O
that	O
is	O
,	O
items	O
in	O
the	O
database	O
)	O
to	O
which	O
the	O
user	O
has	O
applied	O
a	O
lock	B-Operating_System
,	O
which	O
gives	O
exclusive	O
access	O
to	O
the	O
record	B-Operating_System
until	O
the	O
lock	B-Operating_System
is	O
released	O
.	O
</s>
<s>
In	O
Jet	B-Application
versions	O
before	O
version	O
4	O
,	O
a	O
page	O
locking	B-Operating_System
model	O
is	O
used	O
,	O
and	O
in	O
Jet	B-Application
4	O
,	O
a	O
record	B-Operating_System
locking	I-Operating_System
model	O
is	O
employed	O
.	O
</s>
<s>
Microsoft	O
databases	B-Application
are	O
organized	O
into	O
data	O
"	O
pages	O
"	O
,	O
which	O
are	O
fixed-length	O
(	O
2kB	O
before	O
Jet	B-Application
4	O
,	O
4kB	O
in	O
Jet	B-Application
4	O
)	O
data	O
structures	O
.	O
</s>
<s>
The	O
page	O
locking	B-Operating_System
model	O
works	O
by	O
locking	B-Operating_System
the	O
pages	O
,	O
instead	O
of	O
individual	O
records	O
,	O
which	O
though	O
less	O
resource-intensive	O
also	O
means	O
that	O
when	O
a	O
user	O
locks	B-Operating_System
one	O
record	B-Operating_System
,	O
all	O
other	O
records	O
on	O
the	O
same	O
page	O
are	O
collaterally	O
locked	O
.	O
</s>
<s>
In	O
Jet	B-Application
4	O
,	O
the	O
record	B-Operating_System
locking	I-Operating_System
model	O
eliminates	O
collateral	O
locks	B-Operating_System
,	O
so	O
that	O
every	O
record	B-Operating_System
that	O
is	O
not	O
in	O
use	O
is	O
available	O
.	O
</s>
<s>
There	O
are	O
two	O
mechanisms	O
that	O
Microsoft	O
uses	O
for	O
locking	B-Operating_System
:	O
pessimistic	O
locking	B-Operating_System
,	O
and	O
optimistic	O
locking	B-Operating_System
.	O
</s>
<s>
With	O
pessimistic	O
locking	B-Operating_System
,	O
the	O
record	B-Operating_System
or	O
page	O
is	O
locked	O
immediately	O
when	O
the	O
lock	B-Operating_System
is	O
requested	O
,	O
while	O
with	O
optimistic	O
locking	B-Operating_System
,	O
the	O
locking	B-Operating_System
is	O
delayed	O
until	O
the	O
edited	O
record	B-Operating_System
is	O
saved	O
.	O
</s>
<s>
Conflicts	O
are	O
less	O
likely	O
to	O
occur	O
with	O
optimistic	O
locking	B-Operating_System
,	O
since	O
the	O
record	B-Operating_System
is	O
locked	O
only	O
for	O
a	O
short	O
period	O
of	O
time	O
.	O
</s>
<s>
However	O
,	O
with	O
optimistic	O
locking	B-Operating_System
one	O
cannot	O
be	O
certain	O
that	O
the	O
update	O
will	O
succeed	O
because	O
another	O
user	O
could	O
lock	B-Operating_System
the	O
record	B-Operating_System
first	O
.	O
</s>
<s>
With	O
pessimistic	O
locking	B-Operating_System
,	O
the	O
update	O
is	O
guaranteed	O
to	O
succeed	O
once	O
the	O
lock	B-Operating_System
is	O
obtained	O
.	O
</s>
<s>
Other	O
users	O
must	O
wait	O
until	O
the	O
lock	B-Operating_System
is	O
released	O
in	O
order	O
to	O
make	O
their	O
changes	O
.	O
</s>
<s>
Lock	B-Operating_System
conflicts	O
,	O
which	O
either	O
require	O
the	O
user	O
to	O
wait	O
,	O
or	O
cause	O
the	O
request	O
to	O
fail	O
(	O
usually	O
after	O
a	O
timeout	O
)	O
are	O
more	O
common	O
with	O
pessimistic	O
locking	B-Operating_System
.	O
</s>
<s>
Jet	B-Application
supports	O
transaction	B-General_Concept
processing	I-General_Concept
for	O
database	B-Application
systems	I-Application
that	O
have	O
this	O
capability	O
.	O
</s>
<s>
(	O
ODBC	B-Application
systems	O
have	O
one-level	O
transaction	B-General_Concept
processing	I-General_Concept
,	O
while	O
several	O
ISAM	B-Application
systems	O
like	O
Paradox	B-Application
do	O
not	O
support	O
transaction	B-General_Concept
processing	I-General_Concept
.	O
)	O
</s>
<s>
A	O
transaction	O
is	O
a	O
series	O
of	O
operations	O
performed	O
on	O
a	O
database	O
that	O
must	O
be	O
done	O
together	O
this	O
is	O
known	O
as	O
atomicity	B-General_Concept
and	O
is	O
one	O
of	O
the	O
ACID	O
(	O
Atomicity	B-General_Concept
,	O
Consistency	O
,	O
Isolation	O
,	O
and	O
Durability	O
)	O
,	O
concepts	O
considered	O
to	O
be	O
the	O
key	O
transaction	B-General_Concept
processing	I-General_Concept
features	O
of	O
a	O
database	B-Application
management	I-Application
system	I-Application
.	O
</s>
<s>
For	O
transaction	B-General_Concept
processing	I-General_Concept
to	O
work	O
(	O
until	O
Jet	B-Application
3.0	O
)	O
,	O
the	O
programmer	O
needed	O
to	O
begin	O
the	O
transaction	O
manually	O
,	O
perform	O
the	O
operations	O
needed	O
to	O
be	O
performed	O
in	O
the	O
transaction	O
,	O
and	O
then	O
commit	O
(	O
save	O
)	O
the	O
transaction	O
.	O
</s>
<s>
This	O
is	O
called	O
rolling	O
back	O
the	O
transaction	O
,	O
or	O
just	O
rollback	O
,	O
and	O
it	O
restores	O
the	O
state	O
of	O
the	O
database	B-Application
records	I-Application
to	O
precisely	O
the	O
state	O
before	O
the	O
transaction	O
began	O
.	O
</s>
<s>
There	O
is	O
no	O
chance	O
that	O
only	O
some	O
of	O
the	O
updates	O
will	O
end	O
up	O
written	O
to	O
the	O
database	O
;	O
either	O
all	O
will	O
succeed	O
,	O
or	O
the	O
changes	O
will	O
be	O
discarded	O
when	O
the	O
database	B-Application
system	I-Application
restarts	O
.	O
</s>
<s>
With	O
ODBC	B-Application
's	O
in-memory	O
policy	O
,	O
transactions	O
also	O
allow	O
for	O
many	O
updates	O
to	O
a	O
record	B-Operating_System
to	O
occur	O
entirely	O
within	O
memory	O
,	O
with	O
only	O
one	O
expensive	O
disk	O
write	O
at	O
the	O
end	O
.	O
</s>
<s>
Implicit	O
transactions	O
were	O
supported	O
in	O
Jet	B-Application
3.0	O
.	O
</s>
<s>
Implicit	O
transactions	O
in	O
Jet	B-Application
occurred	O
when	O
an	O
SQL	B-Language
DML	B-Language
statement	O
was	O
issued	O
.	O
</s>
<s>
However	O
,	O
it	O
was	O
found	O
that	O
this	O
had	O
a	O
negative	O
performance	O
impact	O
in	O
32-bit	B-Application
Windows	I-Application
(	O
Windows	B-Application
95	I-Application
,	O
Windows	B-Application
98	O
)	O
,	O
so	O
in	O
Jet	B-Application
3.5	O
Microsoft	O
removed	O
implicit	O
transactions	O
when	O
SQL	B-Language
DML	B-Language
statements	O
were	O
made	O
.	O
</s>
<s>
Jet	B-Application
enforces	O
entity	O
integrity	O
and	O
referential	B-General_Concept
integrity	I-General_Concept
.	O
</s>
<s>
Jet	B-Application
will	O
by	O
default	O
prevent	O
any	O
change	O
to	O
a	O
record	B-Operating_System
that	O
breaks	O
referential	B-General_Concept
integrity	I-General_Concept
,	O
but	O
Jet	B-Application
databases	I-Application
can	O
instead	O
use	O
propagation	B-Application
constraints	I-Application
(	O
cascading	O
updates	O
and	O
cascading	O
deletes	O
)	O
to	O
maintain	O
referential	B-General_Concept
integrity	I-General_Concept
.	O
</s>
<s>
Jet	B-Application
also	O
supports	O
"	O
business	O
rules	O
"	O
(	O
also	O
known	O
as	O
"	O
constraints	O
"	O
)	O
,	O
or	O
rules	O
that	O
apply	O
to	O
any	O
column	B-Application
to	O
enforce	O
what	O
data	O
might	O
be	O
placed	O
into	O
the	O
table	O
or	O
column	B-Application
.	O
</s>
<s>
For	O
example	O
,	O
a	O
rule	O
might	O
be	O
applied	O
that	O
does	O
not	O
allow	O
a	O
date	O
to	O
be	O
entered	O
into	O
a	O
date_logged	O
column	B-Application
that	O
is	O
earlier	O
than	O
the	O
current	O
date	O
and	O
time	O
,	O
or	O
a	O
rule	O
might	O
be	O
applied	O
that	O
forces	O
people	O
to	O
enter	O
a	O
positive	O
value	O
into	O
a	O
numeric	O
only	O
field	O
.	O
</s>
<s>
Access	O
to	O
Jet	B-Application
databases	I-Application
is	O
done	O
on	O
a	O
per	O
user-level	O
.	O
</s>
<s>
In	O
Jet	B-Application
4	O
,	O
Microsoft	O
implemented	O
functionality	O
that	O
allows	O
database	O
administrators	O
to	O
set	O
security	O
via	O
the	O
SQL	B-Language
commands	O
CREATE	O
,	O
ADD	O
,	O
ALTER	O
,	O
DROP	O
USER	O
and	O
DROP	O
GROUP	O
.	O
</s>
<s>
These	O
commands	O
are	O
a	O
subset	O
of	O
ANSI	O
SQL	B-Language
92	O
standard	O
,	O
and	O
they	O
also	O
apply	O
to	O
the	O
GRANT/REVOKE	O
commands	O
.	O
</s>
<s>
When	O
Jet	B-Application
2	O
was	O
released	O
,	O
security	O
could	O
also	O
be	O
set	O
programmatically	O
through	O
DAO	B-Library
.	O
</s>
<s>
Queries	O
are	O
the	O
mechanisms	O
that	O
Jet	B-Application
uses	O
to	O
retrieve	O
data	O
from	O
the	O
database	O
.	O
</s>
<s>
They	O
can	O
be	O
defined	O
in	O
Microsoft	B-Device
QBE	I-Device
(	O
Query	O
By	O
Example	O
)	O
,	O
through	O
the	O
Microsoft	B-Application
Access	I-Application
SQL	B-Language
Window	O
or	O
through	O
Access	O
Basic	O
's	O
Data	B-Library
Access	I-Library
Objects	I-Library
(	O
DAO	B-Library
)	O
language	O
.	O
</s>
<s>
These	O
are	O
then	O
converted	O
to	O
an	O
SQL	B-Language
SELECT	I-Language
statement	O
.	O
</s>
<s>
The	O
query	O
is	O
then	O
compiled	O
this	O
involves	O
parsing	O
the	O
query	O
(	O
involves	O
syntax	O
checking	O
and	O
determining	O
the	O
columns	O
to	O
query	O
in	O
the	O
database	O
table	O
)	O
,	O
then	O
converted	O
into	O
an	O
internal	O
Jet	B-Application
query	O
object	O
format	O
,	O
which	O
is	O
then	O
tokenized	O
and	O
organised	O
into	O
a	O
tree	O
like	O
structure	O
.	O
</s>
<s>
In	O
Jet	B-Application
3.0	O
onwards	O
these	O
are	O
then	O
optimised	O
using	O
the	O
Microsoft	O
Rushmore	O
query	O
optimisation	O
technology	O
.	O
</s>
<s>
Jet	B-Application
passes	O
the	O
data	O
retrieved	O
for	O
the	O
query	O
in	O
a	O
dynaset	B-General_Concept
.	O
</s>
<s>
Instead	O
of	O
having	O
the	O
query	O
result	O
stored	O
in	O
a	O
temporary	O
table	O
,	O
where	O
the	O
data	O
cannot	O
be	O
updated	O
directly	O
by	O
the	O
user	O
,	O
the	O
dynaset	B-General_Concept
allows	O
the	O
user	O
to	O
view	O
and	O
update	O
the	O
data	O
contained	O
in	O
the	O
dynaset	B-General_Concept
.	O
</s>
<s>
Thus	O
,	O
if	O
a	O
university	O
lecturer	O
queries	O
all	O
students	O
who	O
received	O
a	O
distinction	O
in	O
their	O
assignment	O
and	O
finds	O
an	O
error	O
in	O
that	O
student	O
's	O
record	B-Operating_System
,	O
they	O
would	O
only	O
need	O
to	O
update	O
the	O
data	O
in	O
the	O
dynaset	B-General_Concept
,	O
which	O
would	O
automatically	O
update	O
the	O
student	O
's	O
database	B-Application
record	I-Application
without	O
the	O
need	O
for	O
them	O
to	O
send	O
a	O
specific	O
update	O
query	O
after	O
storing	O
the	O
query	O
results	O
in	O
a	O
temporary	O
table	O
.	O
</s>
<s>
Jet	B-Application
version	O
Jet	B-Application
engine	O
DLL	O
file	O
name	O
Supported	O
database	O
versions	O
1.0	O
1.0	O
1.1	O
1.10.0001	O
MSAJT110.DLL	O
2.0	O
2.00.0000	O
MSAJT200.DLL	O
2.5	O
2.50.1606	O
MSAJT200.DLL	O
3.0	O
3.0.0.2118	O
MSJT3032.DLL	O
3.5	O
3.51.3328.0	O
MSJET35.DLL	O
4.0	O
SP8	O
4.0.8015.0	O
MSJET40.DLL	O
ACE	O
12	O
12.0.xxxx.xxxx	O
ACECORE.DLL	O
ACE	O
14	O
14.0.xxxx.xxxx	O
ACECORE.DLL	O
ACE	O
15	O
15.0.xxxx.xxxx	O
ACECORE.DLL	O
ACE	O
16	O
16.0.xxxx.xxxx	O
ACECORE.DLL	O
Sources	O
:	O
</s>
<s>
Application/Version	O
Jet	B-Application
version	O
Microsoft	B-Application
Access	I-Application
1.0	O
1.0	O
Microsoft	B-Application
Access	I-Application
1.1	O
1.1	O
Microsoft	B-Application
Access	I-Application
2.0	O
2.0	O
Microsoft	B-Application
Access	I-Application
2.0	O
Service	O
Pack	O
2.5	O
3.0	O
3.5	O
Microsoft	B-Application
Access	I-Application
2000	O
4.0	O
SP1	O
Microsoft	B-Application
Access	I-Application
2002	I-Application
The	O
Access	B-Application
2002	I-Application
setup	O
program	O
only	O
updated	O
system	O
files	O
on	O
certain	O
versions	O
of	O
Windows	B-Application
and	O
to	O
a	O
certain	O
level	O
.	O
</s>
<s>
Microsoft	B-Application
Access	I-Application
2003	O
Access	O
2003	O
relied	O
on	O
the	O
Jet	B-Application
engine	O
component	O
of	O
the	O
operating	O
system	O
for	O
its	O
data	O
storage	O
and	O
query	B-Application
processing	I-Application
.	O
</s>
<s>
Microsoft	B-Application
Access	I-Application
2007	I-Application
ACE	O
12	O
Microsoft	B-Application
Access	I-Application
2010	O
ACE	O
14	O
Microsoft	B-Application
Access	I-Application
2013	O
ACE	O
15	O
Microsoft	B-Application
Access	I-Application
2016	O
ACE	O
16	O
Visual	B-Language
Basic	I-Language
3.0	O
1.1	O
Visual	B-Language
Basic	I-Language
Compatibility	O
Layer	O
2.0	O
Visual	B-Language
Basic	I-Language
4.0	O
16-bit	O
2.5	O
Visual	B-Language
Basic	I-Language
4.0	O
32-bit	O
3.0	O
Visual	B-Language
Basic	I-Language
5.0	O
3.5	O
Visual	B-Application
C++	I-Application
4.X	O
3.0	O
Visual	B-Application
C++	I-Application
5.0	O
3.5	O
3.0	O
Internet	B-Application
Information	I-Application
Server	I-Application
3.0	O
3.5	O
SQL	B-Application
Server	I-Application
7.0	O
4.0	O
Redistributable	O
installers	O
Jet	B-Application
3.51	O
web	O
download	O
3.5	O
+	O
MDAC	B-Library
2.1	O
4.0	O
SP1	O
MDAC	B-Library
2.5	O
4.0	O
SP3	O
to	O
SP6+	O
Jet	B-Application
4.0	O
4.0	O
SP3	O
to	O
SP8	O
2007	O
Office	O
System	O
Driver	O
ACE	O
12	O
Microsoft	B-Application
Access	I-Application
Database	B-General_Concept
Engine	I-General_Concept
2010	O
ACE	O
14	O
Microsoft	B-Application
Access	I-Application
Database	B-General_Concept
Engine	I-General_Concept
2016	O
ACE	O
16	O
Operating	O
systems	O
Windows	B-Device
Me	I-Device
4.0	O
SP3	O
Windows	B-Application
2000	I-Application
4.0	O
SP3	O
Windows	B-Application
XP	I-Application
4.0	O
SP5+	O
Windows	B-Application
Server	I-Application
2003	I-Application
4.0	O
SP6+	O
Windows	B-Application
Vista	I-Application
4.0	O
SP8+	O
Windows	B-Device
Server	I-Device
2008	I-Device
4.0	O
SP8+	O
Windows	B-Device
7	I-Device
4.0	O
SP8+	O
Sources	O
:	O
</s>
<s>
Jet	B-Application
originally	O
started	O
in	O
1992	O
as	O
an	O
underlying	O
data	O
access	O
technology	O
that	O
came	O
from	O
a	O
Microsoft	O
internal	O
database	O
product	O
development	O
project	O
,	O
code	O
named	O
Cirrus	O
.	O
</s>
<s>
Cirrus	O
was	O
developed	O
from	O
a	O
pre-release	O
version	O
of	O
Visual	B-Language
Basic	I-Language
code	O
and	O
was	O
used	O
as	O
the	O
database	B-General_Concept
engine	I-General_Concept
of	O
Microsoft	B-Application
Access	I-Application
.	O
</s>
<s>
"	O
It	O
would	O
be	O
reasonably	O
accurate	O
to	O
say	O
that	O
up	O
until	O
that	O
stage	O
Jet	B-Application
was	O
more	O
the	O
name	O
of	O
the	O
team	O
that	O
was	O
assigned	O
to	O
work	O
on	O
the	O
DB	O
engine	O
modules	B-Architecture
of	O
Access	O
rather	O
than	O
a	O
component	O
team	O
.	O
</s>
<s>
That	O
's	O
why	O
they	O
've	O
had	O
all	O
those	O
Jet/ODBC	O
problems	O
in	O
VB	O
3.0.	O
"	O
</s>
<s>
Jet	B-Application
became	O
more	O
componentised	O
when	O
Access	O
2.0	O
was	O
released	O
because	O
the	O
Access	O
ODBC	B-Application
developers	O
used	O
parts	O
of	O
the	O
Jet	B-Application
code	O
to	O
produce	O
the	O
ODBC	B-Application
driver	O
.	O
</s>
<s>
A	O
retrofit	O
was	O
provided	O
that	O
allowed	O
Visual	O
Basic	O
3.0	O
users	O
to	O
use	O
the	O
updated	O
Jet	B-Application
issued	O
in	O
Access	O
2.0	O
.	O
</s>
<s>
Jet	B-Application
2.0	O
was	O
released	O
as	O
several	O
dynamic	O
linked	O
libraries	O
(	O
DLLs	O
)	O
that	O
were	O
utilised	O
by	O
application	B-Application
software	I-Application
,	O
such	O
as	O
Microsoft	O
's	O
Access	O
database	O
.	O
</s>
<s>
DLLs	O
in	O
Windows	B-Application
are	O
"	O
libraries	O
"	O
of	O
common	O
code	O
that	O
can	O
be	O
used	O
by	O
more	O
than	O
one	O
applicationby	O
keeping	O
code	O
that	O
more	O
than	O
one	O
application	O
uses	O
under	O
a	O
common	O
library	O
which	O
each	O
of	O
these	O
applications	O
can	O
use	O
independently	O
code	O
maintenance	O
is	O
reduced	O
and	O
the	O
functionality	O
of	O
applications	O
increases	O
,	O
with	O
less	O
development	O
effort	O
.	O
</s>
<s>
Jet	B-Application
2.0	O
comprised	O
three	O
DLLs	O
:	O
the	O
Jet	B-Application
DLL	O
,	O
the	O
Data	B-Library
Access	I-Library
Objects	I-Library
(	O
DAO	B-Library
)	O
DLL	O
and	O
several	O
external	O
ISAM	B-Application
DLLs	O
.	O
</s>
<s>
The	O
Jet	B-Application
DLL	O
determined	O
what	O
sort	O
of	O
database	O
it	O
was	O
accessing	O
,	O
and	O
how	O
to	O
perform	O
what	O
was	O
requested	O
of	O
it	O
.	O
</s>
<s>
If	O
the	O
data	O
source	O
was	O
an	O
MDB	O
file	O
(	O
a	O
Microsoft	B-Application
Access	I-Application
format	O
)	O
then	O
it	O
would	O
directly	O
read	O
and	O
write	O
the	O
data	O
to	O
the	O
file	O
.	O
</s>
<s>
If	O
the	O
data	O
source	O
was	O
external	O
,	O
then	O
it	O
would	O
call	O
on	O
the	O
correct	O
ODBC	B-Application
driver	O
to	O
perform	O
its	O
request	O
.	O
</s>
<s>
The	O
DAO	B-Library
DLL	O
was	O
a	O
component	O
that	O
programmers	O
could	O
use	O
to	O
interface	B-Application
with	O
the	O
Jet	B-Application
engine	O
,	O
and	O
was	O
mainly	O
used	O
by	O
Visual	B-Language
Basic	I-Language
and	O
Access	O
Basic	O
programmers	O
.	O
</s>
<s>
The	O
ISAM	B-Application
DLLs	O
were	O
a	O
set	O
of	O
modules	B-Architecture
that	O
allowed	O
Jet	B-Application
to	O
access	O
three	O
ISAM	B-Application
based	O
databases	B-Application
:	O
xBase	B-Language
,	O
Paradox	B-Application
and	O
Btrieve	B-Application
.	O
</s>
<s>
Jet	B-Application
2.0	O
was	O
replaced	O
with	O
Jet	B-Application
2.1	O
,	O
which	O
used	O
the	O
same	O
database	O
structure	O
but	O
different	O
locking	B-Operating_System
strategies	O
,	O
making	O
it	O
incompatible	O
with	O
Jet	B-Application
2.0	O
.	O
</s>
<s>
Jet	B-Application
3.0	O
included	O
many	O
enhancements	O
,	O
including	O
a	O
new	O
index	B-Data_Structure
structure	O
that	O
reduced	O
storage	O
size	O
and	O
the	O
time	O
that	O
was	O
taken	O
to	O
create	O
indices	O
that	O
were	O
highly	O
duplicated	O
,	O
the	O
removal	O
of	O
read	B-Operating_System
locks	I-Operating_System
on	O
index	B-Data_Structure
pages	O
,	O
a	O
new	O
mechanism	O
for	O
page	O
reuse	O
,	O
a	O
new	O
compacting	O
method	O
for	O
which	O
compacting	O
the	O
database	O
resulted	O
in	O
the	O
indices	O
being	O
stored	O
in	O
a	O
clustered-index	O
format	O
,	O
a	O
new	O
page	O
allocation	O
mechanism	O
to	O
improve	O
Jet	B-Application
's	O
read-ahead	O
capabilities	O
,	O
improved	O
delete	O
operations	O
that	O
speeded	O
processing	O
,	O
multithreading	B-Operating_System
(	O
three	O
threads	B-Operating_System
were	O
used	O
to	O
perform	O
read	O
ahead	O
,	O
write	O
behind	O
,	O
and	O
cache	O
maintenance	O
)	O
,	O
implicit	O
transactions	O
(	O
users	O
did	O
not	O
have	O
to	O
instruct	O
the	O
engine	O
to	O
start	O
manually	O
and	O
commit	O
transactions	O
to	O
the	O
database	O
)	O
,	O
a	O
new	O
sort	O
engine	O
,	O
long	O
values	O
(	O
such	O
as	O
memos	O
or	O
binary	O
data	O
types	O
)	O
were	O
stored	O
in	O
separate	O
tables	O
,	O
and	O
dynamic	O
buffering	O
(	O
whereby	O
Jet	B-Application
's	O
cache	O
was	O
dynamically	O
allocated	O
at	O
start	O
up	O
and	O
had	O
no	O
limit	O
and	O
which	O
changed	O
from	O
a	O
first	B-Operating_System
in	I-Operating_System
,	I-Operating_System
first	I-Operating_System
out	I-Operating_System
(	O
FIFO	B-Operating_System
)	O
buffer	O
replacement	O
policy	O
to	O
a	O
least	B-General_Concept
recently	I-General_Concept
used	I-General_Concept
(	O
LRU	O
)	O
buffer	O
replacement	O
policy	O
)	O
.	O
</s>
<s>
Jet	B-Application
3.0	O
also	O
allowed	O
for	O
database	O
replication	O
.	O
</s>
<s>
Jet	B-Application
3.0	O
was	O
replaced	O
by	O
Jet	B-Application
3.5	O
,	O
which	O
uses	O
the	O
same	O
database	O
structure	O
,	O
but	O
different	O
locking	B-Operating_System
strategies	O
,	O
making	O
it	O
incompatible	O
with	O
Jet	B-Application
3.0	O
.	O
</s>
<s>
Jet	B-Application
4.0	O
gained	O
numerous	O
additional	O
features	O
and	O
enhancements	O
.	O
</s>
<s>
Unicode	O
character	O
storage	O
support	O
,	O
along	O
with	O
an	O
NT	B-Device
sorting	O
method	O
that	O
was	O
also	O
implemented	O
in	O
the	O
Windows	B-Application
95	I-Application
version	O
;	O
</s>
<s>
Bi-directional	O
replication	O
with	O
MS	B-Application
SQL	I-Application
Server	I-Application
.	O
</s>
<s>
Microsoft	B-Application
Access	I-Application
versions	O
from	O
Access	O
2000	O
to	O
Access	O
2010	O
included	O
an	O
"	O
Upsizing	B-Application
Wizard	O
"	O
which	O
could	O
"	O
upsize	B-Application
"	O
(	O
upgrade	O
)	O
a	O
Jet	B-Application
database	I-Application
to	O
"	O
an	O
equivalent	O
database	O
on	O
SQL	B-Application
Server	I-Application
with	O
the	O
same	O
table	O
structure	O
,	O
data	O
,	O
and	O
many	O
other	O
attributes	O
of	O
the	O
original	O
database	O
"	O
.	O
</s>
<s>
Reports	O
,	O
queries	O
,	O
macros	O
and	O
security	O
were	O
not	O
handled	O
by	O
this	O
tool	O
,	O
meaning	O
that	O
some	O
manual	O
modifications	O
might	O
have	O
been	O
needed	O
if	O
the	O
application	O
was	O
heavily	O
reliant	O
on	O
these	O
Jet	B-Application
features	O
.	O
</s>
<s>
A	O
standalone	O
version	O
of	O
the	O
Jet	B-Application
4	O
database	B-General_Concept
engine	I-General_Concept
was	O
a	O
component	O
of	O
Microsoft	B-Library
Data	I-Library
Access	I-Library
Components	I-Library
(	O
MDAC	B-Library
)	O
,	O
and	O
was	O
included	O
in	O
every	O
version	O
of	O
Windows	B-Application
from	O
Windows	B-Application
2000	I-Application
on	O
.	O
</s>
<s>
The	O
Jet	B-Application
database	I-Application
engine	I-Application
was	O
only	O
32-bit	O
and	O
did	O
not	O
run	O
natively	O
under	O
64-bit	B-Device
versions	O
of	O
Windows	B-Application
.	O
</s>
<s>
This	O
meant	O
that	O
native	O
64-bit	B-Device
applications	O
(	O
such	O
as	O
the	O
64-bit	B-Device
versions	O
of	O
SQL	B-Application
Server	I-Application
)	O
could	O
not	O
access	O
data	O
stored	O
in	O
MDB	O
files	O
through	O
ODBC	B-Application
,	O
OLE	B-Language
DB	I-Language
,	O
or	O
any	O
other	O
means	O
,	O
except	O
through	O
intermediate	O
32-bit	O
software	O
(	O
running	O
in	O
WoW64	B-Application
)	O
that	O
acted	O
as	O
a	O
proxy	O
for	O
the	O
64-bit	B-Device
client	O
.	O
</s>
<s>
With	O
version	O
2007	O
onwards	O
,	O
Access	O
includes	O
an	O
Office-specific	O
version	O
of	O
Jet	B-Application
,	O
initially	O
called	O
the	O
Office	B-Application
Access	I-Application
Connectivity	O
Engine	O
(	O
ACE	O
)	O
,	O
but	O
which	O
is	O
now	O
called	O
the	O
Access	B-Application
Database	I-Application
Engine	I-Application
(	O
However	O
MS-Access	O
consultants	O
and	O
VBA	O
developers	O
who	O
specialize	O
in	O
MS-Access	O
are	O
more	O
likely	O
to	O
refer	O
to	O
it	O
as	O
"	O
the	O
ACE	O
Database	B-General_Concept
Engine	I-General_Concept
"	O
)	O
.	O
</s>
<s>
This	O
engine	O
was	O
backward-compatible	O
with	O
previous	O
versions	O
of	O
the	O
Jet	B-Application
engine	O
,	O
so	O
it	O
could	O
read	O
and	O
write	O
(	O
.mdb	O
)	O
files	O
from	O
earlier	O
Access	O
versions	O
.	O
</s>
<s>
It	O
introduced	O
a	O
new	O
default	O
file	O
format	O
,	O
(	O
.accdb	O
)	O
,	O
that	O
brought	O
several	O
improvements	O
to	O
Access	O
,	O
including	O
complex	O
data	O
types	O
such	O
as	O
multivalue	O
fields	O
,	O
the	O
attachment	O
data	O
type	O
and	O
history	O
tracking	O
in	O
memo	O
fields	O
.	O
</s>
<s>
It	O
also	O
brought	O
security	O
changes	O
and	O
encryption	O
improvements	O
and	O
enabled	O
integration	O
with	O
Microsoft	B-Protocol
Windows	I-Protocol
SharePoint	I-Protocol
Services	I-Protocol
3.0	O
and	O
Microsoft	B-Application
Office	I-Application
Outlook	I-Application
2007	O
.	O
</s>
<s>
The	O
engine	O
in	O
Microsoft	B-Application
Access	I-Application
2010	O
discontinued	O
support	O
for	O
Access	O
1.0	O
,	O
Access	O
2.0	O
,	O
Lotus	O
1-2-3	O
and	O
Paradox	B-Application
files	O
.	O
</s>
<s>
A	O
64-bit	B-Device
version	O
of	O
Access	O
2010	O
and	O
its	O
ACE	O
Driver/Provider	O
was	O
introduced	O
,	O
which	O
in	O
essence	O
provides	O
a	O
64-bit	B-Device
version	O
of	O
Jet	B-Application
.	O
</s>
<s>
The	O
driver	O
is	O
not	O
part	O
of	O
the	O
Windows	B-Application
operating	I-Application
system	I-Application
,	O
but	O
is	O
available	O
as	O
a	O
redistributable	O
.	O
</s>
<s>
The	O
engine	O
in	O
Microsoft	B-Application
Access	I-Application
2013	O
discontinued	O
support	O
for	O
Access	O
95	O
,	O
Access	B-Application
97	I-Application
and	O
xBase	B-Language
files	O
,	O
and	O
it	O
also	O
discontinued	O
support	O
for	O
replication	O
.	O
</s>
<s>
Version	O
1608	O
of	O
Microsoft	B-Application
Access	I-Application
2016	O
restored	O
support	O
for	O
xBase	B-Language
files	O
,	O
and	O
Version	O
1703	O
introduced	O
a	O
Large	O
Number	O
data	O
type	O
.	O
</s>
<s>
From	O
a	O
data	O
access	O
technology	O
standpoint	O
,	O
Jet	B-Application
is	O
considered	O
a	O
deprecated	O
technology	O
by	O
Microsoft	O
,	O
but	O
Microsoft	O
continues	O
to	O
support	O
ACE	O
as	O
part	O
of	O
Microsoft	B-Application
Access	I-Application
.	O
</s>
<s>
Microsoft	O
provides	O
the	O
JET	B-Application
drivers	O
for	O
Microsoft	B-Application
Windows	I-Application
only	O
and	O
third	O
party	O
software	O
support	O
for	O
JET	B-Application
databases	I-Application
is	O
almost	O
exclusively	O
found	O
on	O
Windows	B-Application
.	O
</s>
<s>
However	O
,	O
there	O
are	O
open	B-Application
source	I-Application
projects	O
that	O
enable	O
working	O
with	O
JET	B-Application
databases	I-Application
on	O
other	O
platforms	O
including	O
Linux	B-Application
.	O
</s>
<s>
Notably	O
,	O
MDB	B-Language
Tools	I-Language
and	O
its	O
much	O
extended	O
Java	O
port	O
named	O
as	O
well	O
as	O
.	O
</s>
