<s>
Extensible	B-Application
Storage	I-Application
Engine	I-Application
(	O
ESE	O
)	O
,	O
also	O
known	O
as	O
JET	B-Application
Blue	I-Application
,	O
is	O
an	O
ISAM	B-Application
(	O
indexed	B-Application
sequential	I-Application
access	I-Application
method	I-Application
)	O
data	O
storage	O
technology	O
from	O
Microsoft	O
.	O
</s>
<s>
ESE	O
is	O
the	O
core	O
of	O
Microsoft	B-Operating_System
Exchange	I-Operating_System
Server	I-Operating_System
,	O
Active	B-Protocol
Directory	I-Protocol
,	O
and	O
Windows	B-Application
Search	I-Application
.	O
</s>
<s>
It	O
's	O
also	O
used	O
by	O
a	O
number	O
of	O
Windows	B-Application
components	O
including	O
Windows	B-Application
Update	O
client	O
and	O
Help	O
and	O
Support	O
Center	O
.	O
</s>
<s>
ESE	O
provides	O
transacted	B-General_Concept
data	O
update	O
and	O
retrieval	O
.	O
</s>
<s>
A	O
crash	O
recovery	O
mechanism	O
is	O
provided	O
so	O
that	O
data	B-General_Concept
consistency	I-General_Concept
is	O
maintained	O
even	O
in	O
the	O
event	O
of	O
a	O
system	O
crash	O
.	O
</s>
<s>
The	O
ESE	O
Runtime	O
(	O
ESENT.DLL	O
)	O
has	O
shipped	O
in	O
every	O
Windows	B-Application
release	O
since	O
Windows	B-Application
2000	I-Application
,	O
with	O
native	O
x64	B-Device
version	O
of	O
the	O
ESE	O
runtime	O
shipping	O
with	O
x64	B-Device
versions	O
of	O
Windows	B-Application
XP	I-Application
and	O
Windows	B-Application
Server	I-Application
2003	I-Application
.	O
</s>
<s>
Microsoft	B-Operating_System
Exchange	I-Operating_System
,	O
up	O
to	O
Exchange	O
2003	O
shipped	O
with	O
only	O
the	O
32-bit	O
edition	O
,	O
as	O
it	O
was	O
the	O
only	O
supported	O
platform	O
.	O
</s>
<s>
An	O
ESE	O
database	O
looks	O
like	O
a	O
single	O
file	O
to	O
Windows	B-Application
.	O
</s>
<s>
Internally	O
the	O
database	O
is	O
a	O
collection	O
of	O
2	O
,	O
4	O
,	O
8	O
,	O
16	O
,	O
or	O
32	O
KB	O
pages	O
(	O
16	O
and	O
32	O
KB	O
page	O
options	O
are	O
only	O
available	O
in	O
Windows	B-Application
7	O
and	O
Exchange	O
2010	O
)	O
,	O
arranged	O
in	O
a	O
balanced	O
B-tree	B-Architecture
structure	O
.	O
</s>
<s>
While	O
detached	O
,	O
a	O
database	O
may	O
be	O
copied	O
using	O
standard	O
Windows	B-Application
utilities	O
.	O
</s>
<s>
A	O
database	O
may	O
physically	O
reside	O
on	O
any	O
device	O
supported	O
for	O
directly	O
addressable	O
I/O	O
operations	O
by	O
Windows	B-Application
.	O
</s>
<s>
Clustered	O
and	O
non-clustered	O
indexes	O
are	O
represented	O
using	O
B+	O
trees	O
.	O
</s>
<s>
The	O
maximum	O
size	O
of	O
a	O
record	O
is	O
8110	O
bytes	B-Application
for	O
8	O
kilobyte	O
pages	O
with	O
the	O
exception	O
of	O
long	O
value	O
columns	O
.	O
</s>
<s>
When	O
a	O
long	O
value	O
reference	O
is	O
stored	O
in	O
a	O
record	O
,	O
only	O
9	O
bytes	B-Application
of	O
in-record	O
data	O
are	O
required	O
.	O
</s>
<s>
Variable	O
columns	O
take	O
up	O
2-bytes	O
to	O
determine	O
NULLity	O
and	O
size	O
,	O
and	O
a	O
variable	O
amount	O
of	O
space	O
in	O
each	O
record	O
in	O
which	O
that	O
column	O
is	O
set	O
.	O
</s>
<s>
When	O
tagged	O
columns	O
are	O
set	O
in	O
a	O
record	O
,	O
each	O
instance	O
of	O
a	O
tagged	O
column	O
takes	O
approximately	O
4-bytes	O
of	O
space	O
in	O
addition	O
to	O
the	O
size	O
of	O
the	O
tagged	O
column	O
instance	O
value	O
.	O
</s>
<s>
When	O
the	O
number	O
of	O
instances	O
of	O
a	O
single	O
tagged	O
column	O
is	O
large	O
,	O
the	O
overhead	O
per	O
tagged	O
column	O
instance	O
is	O
approximately	O
2-bytes	O
.	O
</s>
<s>
They	O
are	O
stored	O
in	O
separate	O
B+tree	O
from	O
the	O
clustered	O
index	O
keyed	O
by	O
long	O
value	O
id	O
and	O
byte	B-Application
offset	O
.	O
</s>
<s>
ESE	O
supports	O
append	O
,	O
byte	B-Application
range	O
overwrite	O
,	O
and	O
set	O
size	O
for	O
these	O
columns	O
.	O
</s>
<s>
Optionally	O
,	O
database	B-General_Concept
engine	I-General_Concept
can	O
erase	O
records	O
with	O
zero	O
value	O
of	O
the	O
column	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
a	O
Text	O
column	O
value	O
is	O
“	O
I	O
love	O
JET	B-Application
Blue	I-Application
”	O
,	O
and	O
the	O
index	O
is	O
configured	O
to	O
have	O
a	O
minimum	O
tuple	O
size	O
of	O
4	O
characters	O
and	O
a	O
maximum	O
tuple	O
length	O
of	O
10	O
characters	O
,	O
then	O
the	O
following	O
sub-strings	O
will	O
be	O
indexed	O
:	O
</s>
<s>
Even	O
though	O
tuple	O
indexes	O
can	O
be	O
very	O
large	O
,	O
they	O
can	O
significantly	O
speed	O
queries	O
of	O
the	O
form	O
:	O
find	O
all	O
records	O
containing	O
“	O
JET	B-Application
Blue	I-Application
”	O
.	O
</s>
<s>
Since	O
a	O
transaction	O
may	O
make	O
changes	O
based	O
on	O
data	O
read	O
that	O
has	O
already	O
been	O
updated	O
in	O
another	O
transaction	O
,	O
multi-versioning	O
by	O
itself	O
does	O
not	O
guarantee	O
serializable	B-Operating_System
transactions	O
.	O
</s>
<s>
However	O
,	O
serializability	B-Operating_System
can	O
be	O
achieved	O
when	O
desired	O
by	O
simply	O
using	O
explicit	O
record	O
read	O
locks	O
to	O
lock	O
read	O
data	O
that	O
updates	O
are	O
based	O
upon	O
.	O
</s>
<s>
When	O
an	O
ESENT	B-Application
database	O
is	O
created	O
,	O
the	O
physical	O
disk	B-Application
sector	I-Application
size	O
is	O
stored	O
with	O
the	O
database	O
.	O
</s>
<s>
When	O
a	O
physical	O
drive	O
is	O
cloned	O
or	O
restored	O
from	O
a	O
drive	O
image	O
to	O
a	O
drive	O
that	O
uses	O
a	O
different	O
physical	O
sector	O
size	O
(	O
Advanced	B-Device
Format	I-Device
Drives	I-Device
)	O
,	O
ESENT	B-Application
will	O
report	O
errors	O
.	O
</s>
<s>
For	O
Windows	B-Application
Vista	O
or	O
Windows	B-Application
Server	O
2008	O
see	O
KB2470478	O
.	O
</s>
<s>
For	O
Windows	B-Application
7	O
or	O
Windows	B-Application
Server	O
2008	O
R2	O
see	O
KB982018	O
.	O
</s>
<s>
JET	B-Application
Blue	I-Application
was	O
originally	O
developed	O
by	O
Microsoft	O
as	O
a	O
prospective	O
upgrade	O
for	O
the	O
JET	B-Application
Red	I-Application
database	B-General_Concept
engine	I-General_Concept
in	O
Microsoft	B-Application
Access	I-Application
,	O
but	O
was	O
never	O
used	O
in	O
this	O
role	O
.	O
</s>
<s>
Instead	O
,	O
it	O
went	O
on	O
to	O
be	O
used	O
by	O
Exchange	B-Operating_System
Server	I-Operating_System
,	O
Active	B-Protocol
Directory	I-Protocol
,	O
File	B-Protocol
Replication	I-Protocol
Service	I-Protocol
(	O
FRS	O
)	O
,	O
Security	O
Configuration	O
Editor	O
,	O
Certificate	O
Services	O
,	O
Windows	B-Device
Internet	I-Device
Name	I-Device
Service	I-Device
(	O
WINS	O
)	O
and	O
a	O
host	O
of	O
other	O
Microsoft	O
services	O
,	O
applications	O
and	O
Windows	B-Application
components	O
.	O
</s>
<s>
Over	O
the	O
next	O
year	O
a	O
team	O
of	O
four	O
developers	O
worked	O
for	O
Allen	O
to	O
largely	O
complete	O
the	O
ISAM	B-Application
.	O
</s>
<s>
Microsoft	O
already	O
had	O
the	O
BC7	O
ISAM	B-Application
(	O
JET	B-Application
Red	I-Application
)	O
but	O
began	O
the	O
Data	O
Access	O
Engine	O
(	O
DAE	O
)	O
effort	O
to	O
build	O
a	O
more	O
robust	O
database	B-General_Concept
engine	I-General_Concept
as	O
an	O
entry	O
in	O
the	O
then	O
new	O
client-server	O
architecture	O
realm	O
.	O
</s>
<s>
In	O
the	O
spring	O
of	O
1990	O
,	O
BC7	O
ISAM	B-Application
and	O
DAE	O
teams	O
were	O
joined	O
to	O
become	O
the	O
Joint	B-Application
Engine	I-Application
Technology	I-Application
(	O
JET	B-Application
)	O
effort	O
;	O
responsible	O
for	O
producing	O
two	O
engines	O
a	O
v1	O
(	O
JET	B-Application
Red	I-Application
)	O
and	O
a	O
v2	O
(	O
JET	B-Application
Blue	I-Application
)	O
that	O
would	O
conform	O
to	O
the	O
same	O
API	O
specification	O
(	O
JET	B-Application
API	O
)	O
.	O
</s>
<s>
DAE	O
became	O
JET	B-Application
Blue	I-Application
for	O
the	O
color	O
of	O
the	O
flag	O
of	O
Israel	O
.	O
</s>
<s>
BC7	O
ISAM	B-Application
became	O
JET	B-Application
Red	I-Application
for	O
the	O
color	O
of	O
the	O
flag	O
of	O
Russia	O
.	O
</s>
<s>
While	O
JET	B-Application
Blue	I-Application
and	O
JET	B-Application
Red	I-Application
were	O
written	O
to	O
the	O
same	O
API	O
specification	O
,	O
they	O
shared	O
no	O
ISAM	B-Application
code	O
whatsoever	O
.	O
</s>
<s>
They	O
did	O
both	O
support	O
a	O
common	O
query	O
processor	O
,	O
QJET	O
,	O
which	O
later	O
together	O
with	O
the	O
BC7	O
ISAM	B-Application
became	O
synonymous	O
with	O
JET	B-Application
Red	I-Application
.	O
</s>
<s>
JET	B-Application
Blue	I-Application
first	O
shipped	O
in	O
1994	O
as	O
an	O
ISAM	B-Application
for	O
WINS	O
,	O
DHCP	O
,	O
and	O
the	O
now	O
defunct	O
RPL	B-Device
services	O
in	O
Windows	B-Application
NT	O
3.5	O
.	O
</s>
<s>
It	O
shipped	O
again	O
as	O
the	O
storage	B-General_Concept
engine	I-General_Concept
for	O
Microsoft	B-Operating_System
Exchange	I-Operating_System
in	O
1996	O
.	O
</s>
<s>
Additional	O
Windows	B-Application
services	O
chose	O
JET	B-Application
Blue	I-Application
as	O
their	O
storage	O
technology	O
and	O
by	O
2000	O
every	O
version	O
of	O
Windows	B-Application
began	O
to	O
ship	O
with	O
JET	B-Application
Blue	I-Application
.	O
</s>
<s>
JET	B-Application
Blue	I-Application
was	O
used	O
by	O
Active	B-Protocol
Directory	I-Protocol
and	O
became	O
part	O
of	O
a	O
special	O
set	O
of	O
Windows	B-Application
code	O
called	O
the	O
Trusted	O
Computing	O
Base	O
(	O
TCB	O
)	O
.	O
</s>
<s>
The	O
number	O
of	O
Microsoft	O
applications	O
using	O
JET	B-Application
Blue	I-Application
continues	O
to	O
grow	O
and	O
the	O
JET	B-Application
Blue	I-Application
API	O
was	O
published	O
in	O
2005	O
to	O
facilitate	O
usage	O
by	O
an	O
ever-increasing	O
number	O
of	O
applications	O
and	O
services	O
both	O
within	O
and	O
beyond	O
Windows	B-Application
.	O
</s>
<s>
It	O
was	O
posted	O
to	O
GitHub	O
with	O
the	O
permissive	O
MIT	B-License
License	I-License
.	O
</s>
<s>
While	O
they	O
share	O
a	O
common	O
lineage	O
,	O
there	O
are	O
vast	O
differences	O
between	O
JET	B-Application
Red	I-Application
and	O
ESE	O
.	O
</s>
<s>
JET	B-Application
Red	I-Application
is	O
a	O
file	O
sharing	O
technology	O
,	O
while	O
ESE	O
is	O
designed	O
to	O
be	O
embedded	O
in	O
a	O
server	O
application	O
,	O
and	O
does	O
not	O
share	O
files	O
.	O
</s>
<s>
JET	B-Application
Red	I-Application
makes	O
best	O
effort	O
file	O
recovery	O
,	O
while	O
ESE	O
has	O
write	O
ahead	O
logging	O
and	O
snapshot	O
isolation	O
for	O
guaranteed	O
crash	O
recovery	O
.	O
</s>
<s>
JET	B-Application
Red	I-Application
before	O
version	O
4.0	O
supports	O
only	O
page	O
level	O
locking	O
,	O
while	O
ESE	O
and	O
JET	B-Application
Red	I-Application
version	O
4.0	O
supports	O
record	O
level	O
locking	O
.	O
</s>
<s>
JET	B-Application
Red	I-Application
supports	O
a	O
wide	O
variety	O
of	O
query	O
interfaces	O
,	O
including	O
ODBC	B-Application
and	O
OLE	B-Language
DB	I-Language
.	O
</s>
<s>
ESE	O
does	O
not	O
ship	O
with	O
a	O
query	O
engine	O
but	O
instead	O
relies	O
on	O
applications	O
to	O
write	O
their	O
own	O
queries	O
as	O
C	B-Language
ISAM	B-Application
code	O
.	O
</s>
<s>
JET	B-Application
Red	I-Application
has	O
a	O
maximum	O
database	O
file	O
size	O
of	O
2	O
GiB	O
,	O
while	O
ESE	O
has	O
a	O
maximum	O
database	O
file	O
size	O
of	O
8	O
TiB	O
with	O
4	O
KiB	O
pages	O
,	O
and	O
16	O
TiB	O
with	O
8	O
KiB	O
pages	O
.	O
</s>
