<s>
Anchor	B-Application
modeling	I-Application
is	O
an	O
agile	O
database	B-General_Concept
modeling	B-Application
technique	O
suited	O
for	O
information	O
that	O
changes	O
over	O
time	O
both	O
in	O
structure	O
and	O
content	O
.	O
</s>
<s>
It	O
provides	O
a	O
graphical	O
notation	O
used	O
for	O
conceptual	O
modeling	B-Application
similar	O
to	O
that	O
of	O
entity-relationship	B-Architecture
modeling	I-Architecture
,	O
with	O
extensions	O
for	O
working	O
with	O
temporal	O
data	O
.	O
</s>
<s>
The	O
modeling	B-Application
technique	O
involves	O
four	O
modeling	B-Application
constructs	O
:	O
the	O
anchor	O
,	O
attribute	O
,	O
tie	O
and	O
knot	O
,	O
each	O
capturing	O
different	O
aspects	O
of	O
the	O
domain	O
being	O
modeled	O
.	O
</s>
<s>
The	O
resulting	O
models	O
can	O
be	O
translated	O
to	O
physical	O
database	B-General_Concept
designs	O
using	O
formalized	O
rules	O
.	O
</s>
<s>
When	O
such	O
a	O
translation	O
is	O
done	O
the	O
tables	O
in	O
the	O
relational	B-Application
database	I-Application
will	O
mostly	O
be	O
in	O
the	O
sixth	O
normal	B-Application
form	I-Application
.	O
</s>
<s>
Unlike	O
the	O
star	B-Application
schema	I-Application
(	O
dimensional	O
modelling	O
)	O
and	O
the	O
classical	O
relational	B-Architecture
model	I-Architecture
(	O
3NF	O
)	O
,	O
data	O
vault	O
and	O
anchor	O
modelling	O
are	O
well-suited	O
for	O
capturing	O
changes	O
that	O
occur	O
when	O
a	O
source	O
system	O
is	O
changed	O
or	O
added	O
,	O
but	O
are	O
considered	O
advanced	O
techniques	O
which	O
require	O
experienced	O
data	B-Application
architects	I-Application
.	O
</s>
<s>
Anchor	B-Application
modeling	I-Application
was	O
created	O
in	O
order	O
to	O
take	O
advantage	O
of	O
the	O
benefits	O
from	O
a	O
high	O
degree	O
of	O
normalization	B-Application
while	O
avoiding	O
its	O
drawbacks	O
which	O
higher	O
normal	B-Application
forms	I-Application
have	O
with	O
regards	O
to	O
human	O
readability	O
.	O
</s>
<s>
Performance	O
issues	O
due	O
to	O
extra	O
joins	O
are	O
largely	O
avoided	O
thanks	O
to	O
a	O
feature	O
in	O
modern	O
database	B-General_Concept
engines	O
called	O
join	O
elimination	O
or	O
table	B-Application
elimination	O
.	O
</s>
<s>
In	O
order	O
to	O
handle	O
changes	O
in	O
the	O
information	O
content	O
,	O
anchor	B-Application
modeling	I-Application
emulates	O
aspects	O
of	O
a	O
temporal	O
database	B-General_Concept
in	O
the	O
resulting	O
relational	B-Application
database	I-Application
schema	B-Application
.	O
</s>
<s>
In	O
2004	O
in	O
Sweden	O
came	O
the	O
earliest	O
installations	O
using	O
anchor	B-Application
modeling	I-Application
were	O
made	O
when	O
a	O
data	O
warehouse	O
for	O
an	O
insurance	O
company	O
was	O
built	O
using	O
the	O
technique	O
.	O
</s>
<s>
In	O
2007	O
the	O
technique	O
was	O
being	O
used	O
in	O
a	O
few	O
data	O
warehouses	O
and	O
one	O
online	B-General_Concept
transaction	I-General_Concept
processing	I-General_Concept
(	O
OLTP	B-General_Concept
)	O
system	O
,	O
and	O
it	O
was	O
presented	O
internationally	O
by	O
Lars	O
Rönnbäck	O
at	O
the	O
2007	O
Transforming	O
Data	O
with	O
Intelligence	O
(	O
TDWI	O
)	O
conference	O
in	O
Amsterdam	O
.	O
</s>
<s>
Since	O
then	O
research	O
concerning	O
anchor	B-Application
modeling	I-Application
is	O
being	O
done	O
in	O
a	O
collaboration	O
between	O
the	O
creators	O
Olle	O
Regardt	O
and	O
Lars	O
Rönnbäck	O
and	O
a	O
team	O
at	O
the	O
Department	O
of	O
Computer	O
and	O
Systems	O
Sciences	O
,	O
Stockholm	O
University	O
.	O
</s>
<s>
The	O
first	O
paper	O
,	O
in	O
which	O
anchor	B-Application
modeling	I-Application
is	O
formalized	O
,	O
was	O
presented	O
in	O
2008	O
at	O
the	O
28th	O
International	O
Conference	O
on	O
Conceptual	O
Modeling	B-Application
and	O
won	O
the	O
best	O
paper	O
award	O
.	O
</s>
<s>
A	O
commercial	O
web	O
site	O
provides	O
material	O
on	O
anchor	B-Application
modeling	I-Application
which	O
is	O
free	O
to	O
use	O
under	O
a	O
Creative	O
Commons	O
license	O
.	O
</s>
<s>
An	O
online	O
modeling	B-Application
tool	O
is	O
also	O
available	O
,	O
which	O
is	O
free	O
to	O
use	O
and	O
is	O
open	B-License
source	I-License
.	O
</s>
<s>
Anchor	B-Application
modeling	I-Application
has	O
four	O
basic	O
modeling	B-Application
concepts	O
:	O
anchors	O
,	O
attributes	O
,	O
ties	O
,	O
and	O
knots	O
.	O
</s>
<s>
The	O
symbols	O
resemble	O
those	O
used	O
in	O
entity	O
–	O
relationship	O
modeling	B-Application
,	O
with	O
a	O
couple	O
of	O
extensions	O
.	O
</s>
<s>
Anchor	B-Application
modeling	I-Application
handles	O
two	O
types	O
of	O
informational	O
evolution	O
,	O
which	O
are	O
structural	O
changes	O
and	O
content	O
changes	O
.	O
</s>
<s>
The	O
high	O
degree	O
of	O
normalization	B-Application
makes	O
it	O
possible	O
to	O
non-destructively	O
add	O
the	O
necessary	O
modeling	B-Application
concepts	O
needed	O
to	O
capture	B-General_Concept
a	I-General_Concept
change	I-General_Concept
,	O
in	O
such	O
a	O
way	O
that	O
every	O
previous	O
schema	B-Application
always	O
remains	O
as	O
a	O
subset	O
of	O
the	O
current	O
schema	B-Application
.	O
</s>
<s>
Since	O
the	O
existing	O
schema	B-Application
is	O
not	O
touched	O
,	O
this	O
gives	O
the	O
benefit	O
of	O
being	O
able	O
to	O
evolve	O
the	O
database	B-General_Concept
in	O
a	O
highly	O
iterative	O
manner	O
and	O
without	O
causing	O
any	O
downtime	O
.	O
</s>
<s>
Changes	O
in	O
the	O
content	O
of	O
information	O
is	O
done	O
by	O
emulating	O
similar	O
features	O
of	O
a	O
temporal	O
database	B-General_Concept
in	O
a	O
relational	B-Application
database	I-Application
.	O
</s>
<s>
In	O
anchor	B-Application
modeling	I-Application
,	O
pieces	O
of	O
information	O
can	O
be	O
tied	O
to	O
points	O
in	O
time	O
or	O
to	O
intervals	O
of	O
time	O
(	O
both	O
open	O
and	O
closed	O
)	O
.	O
</s>
<s>
In	O
a	O
relational	B-Application
database	I-Application
this	O
is	O
achieved	O
by	O
adding	O
a	O
single	O
column	B-Application
,	O
with	O
a	O
data	O
type	O
granular	O
enough	O
to	O
capture	O
the	O
speed	O
of	O
the	O
changes	O
,	O
to	O
the	O
table	B-Application
corresponding	O
to	O
the	O
historized	O
attribute	O
or	O
tie	O
.	O
</s>
<s>
This	O
adds	O
a	O
slight	O
complexity	O
as	O
more	O
than	O
one	O
row	B-Application
in	O
the	O
table	B-Application
have	O
to	O
be	O
examined	O
in	O
order	O
to	O
know	O
if	O
an	O
interval	O
is	O
closed	O
or	O
not	O
.	O
</s>
<s>
Points	O
or	O
intervals	O
of	O
time	O
not	O
directly	O
related	O
to	O
the	O
domain	O
being	O
modeled	O
,	O
such	O
as	O
the	O
points	O
of	O
time	O
information	O
entered	O
the	O
database	B-General_Concept
,	O
are	O
handled	O
through	O
the	O
use	O
of	O
metadata	O
in	O
anchor	B-Application
modeling	I-Application
,	O
rather	O
than	O
any	O
of	O
the	O
above-mentioned	O
constructs	O
.	O
</s>
<s>
If	O
information	O
about	O
such	O
changes	O
to	O
the	O
database	B-General_Concept
needs	O
to	O
be	O
kept	O
then	O
bitemporal	O
anchor	B-Application
modeling	I-Application
can	O
be	O
used	O
,	O
where	O
in	O
addition	O
to	O
updates	O
,	O
also	O
delete	O
statements	O
become	O
non-destructive	O
.	O
</s>
<s>
In	O
anchor	B-Application
modeling	I-Application
there	O
is	O
a	O
one-to-one	O
mapping	O
between	O
the	O
symbols	O
used	O
in	O
the	O
conceptual	O
model	O
and	O
tables	O
in	O
the	O
relational	B-Application
database	I-Application
.	O
</s>
<s>
Every	O
anchor	O
,	O
attribute	O
,	O
tie	O
,	O
and	O
knot	O
have	O
a	O
corresponding	O
table	B-Application
in	O
the	O
database	B-General_Concept
with	O
an	O
unambiguously	O
defined	O
structure	O
.	O
</s>
<s>
A	O
conceptual	O
model	O
can	O
thereby	O
be	O
translated	O
to	O
a	O
relational	B-Application
database	I-Application
schema	B-Application
using	O
simple	O
automated	O
rules	O
,	O
and	O
vice	O
versa	O
.	O
</s>
<s>
This	O
is	O
different	O
from	O
many	O
other	O
modeling	B-Application
techniques	O
in	O
which	O
there	O
are	O
complex	O
and	O
sometimes	O
subjective	O
translation	O
steps	O
between	O
the	O
conceptual	O
,	O
logical	O
,	O
and	O
physical	O
levels	O
.	O
</s>
<s>
Anchor	O
tables	O
contain	O
a	O
single	O
column	B-Application
in	O
which	O
identities	O
are	O
stored	O
.	O
</s>
<s>
An	O
example	O
of	O
an	O
anchor	O
for	O
the	O
identities	O
of	O
the	O
nephews	O
of	O
Donald	O
Duck	O
is	O
a	O
set	O
of	O
1-tuples	O
:	O
</s>
<s>
An	O
example	O
of	O
a	O
knot	O
for	O
genders	O
is	O
a	O
set	O
of	O
2-tuples	O
:	O
</s>
<s>
Historized	O
attribute	O
tables	O
have	O
an	O
extra	O
column	B-Application
for	O
storing	O
the	O
starting	O
point	O
of	O
a	O
time	O
interval	O
.	O
</s>
<s>
In	O
a	O
knotted	O
attribute	O
table	B-Application
,	O
the	O
value	O
column	B-Application
is	O
an	O
identity	O
that	O
references	O
a	O
knot	O
table	B-Application
.	O
</s>
<s>
An	O
example	O
of	O
a	O
static	O
attribute	O
for	O
their	O
names	O
is	O
a	O
set	O
of	O
2-tuples	O
:	O
</s>
<s>
An	O
example	O
of	O
a	O
knotted	O
static	O
attribute	O
for	O
their	O
genders	O
is	O
a	O
set	O
of	O
2-tuples	O
:	O
</s>
<s>
An	O
example	O
of	O
a	O
historized	O
attribute	O
for	O
the	O
(	O
changing	O
)	O
colors	O
of	O
their	O
outfits	O
is	O
a	O
set	O
of	O
3-tuples	O
:	O
</s>
<s>
Historized	O
tie	O
tables	O
have	O
an	O
extra	O
column	B-Application
for	O
storing	O
the	O
starting	O
point	O
of	O
a	O
time	O
interval	O
.	O
</s>
<s>
Knotted	O
tie	O
tables	O
have	O
an	O
additional	O
column	B-Application
for	O
each	O
referenced	O
knot	O
.	O
</s>
<s>
An	O
example	O
of	O
a	O
static	O
tie	O
for	O
the	O
sibling	O
relationship	O
is	O
a	O
set	O
of	O
2-tuples	O
:	O
</s>
<s>
The	O
resulting	O
tables	O
will	O
all	O
be	O
in	O
sixth	O
normal	B-Application
form	I-Application
except	O
for	O
ties	O
in	O
which	O
not	O
all	O
columns	O
are	O
part	O
of	O
the	O
primary	O
key	O
.	O
</s>
<s>
In	O
the	O
2000s	O
,	O
several	O
data	O
warehouse	O
data	B-Application
modeling	I-Application
patterns	O
have	O
been	O
introduced	O
with	O
the	O
goal	O
of	O
achieving	O
agile	O
data	O
warehouses	O
,	O
including	O
ensemble	O
modeling	B-Application
forms	O
such	O
as	O
anchor	B-Application
modeling	I-Application
,	O
data	O
vault	O
modeling	B-Application
,	O
focal	O
point	O
modeling	B-Application
,	O
and	O
others	O
.	O
</s>
<s>
In	O
2013	O
at	O
the	O
data	B-Application
modeling	I-Application
conference	O
BI	O
Podium	O
in	O
the	O
Netherlands	O
,	O
Lars	O
Rönnbäck	O
presented	O
a	O
comparison	O
of	O
anchor	B-Application
modeling	I-Application
and	O
data	O
vault	O
modeling	B-Application
.	O
</s>
<s>
The	O
following	O
table	B-Application
is	O
based	O
on	O
this	O
comparison	O
(	O
2013	O
copyleft	B-License
anchormodeling.com	O
)	O
:	O
</s>
