<s>
A	O
tablespace	B-General_Concept
is	O
a	O
storage	O
location	O
where	O
the	O
actual	O
data	O
underlying	O
database	O
objects	O
can	O
be	O
kept	O
.	O
</s>
<s>
It	O
provides	O
a	O
layer	O
of	O
abstraction	O
between	O
physical	O
and	O
logical	O
data	O
,	O
and	O
serves	O
to	O
allocate	O
storage	O
for	O
all	O
DBMS	B-General_Concept
managed	O
segments	O
.	O
</s>
<s>
(	O
A	O
database	O
segment	O
is	O
a	O
database	O
object	O
which	O
occupies	O
physical	O
space	O
such	O
as	O
table	B-Application
data	O
and	O
indexes	B-Data_Structure
.	O
)	O
</s>
<s>
Once	O
created	O
,	O
a	O
tablespace	B-General_Concept
can	O
be	O
referred	O
to	O
by	O
name	O
when	O
creating	O
database	O
segments	O
.	O
</s>
<s>
Tablespaces	B-General_Concept
specify	O
only	O
the	O
database	O
storage	O
locations	O
,	O
not	O
the	O
logical	O
database	O
structure	O
,	O
or	O
database	B-Application
schema	I-Application
.	O
</s>
<s>
For	O
instance	O
,	O
different	O
objects	O
in	O
the	O
same	O
schema	O
may	O
have	O
different	O
underlying	O
tablespaces	B-General_Concept
.	O
</s>
<s>
Similarly	O
,	O
a	O
tablespace	B-General_Concept
may	O
service	O
segments	O
for	O
more	O
than	O
one	O
schema	O
.	O
</s>
<s>
By	O
using	O
tablespaces	B-General_Concept
,	O
an	O
administrator	O
also	O
can	O
control	O
the	O
disk	O
layout	O
of	O
an	O
installation	O
.	O
</s>
<s>
A	O
common	O
use	O
of	O
tablespaces	B-General_Concept
is	O
to	O
optimize	O
performance	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
heavily	O
used	O
index	O
can	O
be	O
placed	O
on	O
a	O
fast	O
SSD	B-Device
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
a	O
database	B-Application
table	I-Application
which	O
contains	O
archived	O
data	O
that	O
is	O
rarely	O
accessed	O
could	O
be	O
stored	O
on	O
a	O
less	O
expensive	O
but	O
slower	O
magnetic	B-Device
hard	I-Device
drive	I-Device
.	O
</s>
<s>
While	O
it	O
is	O
common	O
for	O
tablespaces	B-General_Concept
to	O
store	O
their	O
data	O
in	O
a	O
filesystem	O
file	O
,	O
a	O
single	O
file	O
must	O
be	O
part	O
of	O
a	O
single	O
tablespace	B-General_Concept
.	O
</s>
<s>
Some	O
database	B-Application
management	I-Application
systems	I-Application
allow	O
tablespaces	B-General_Concept
to	O
be	O
configured	O
directly	O
over	O
operating-system	O
device	O
entries	O
,	O
called	O
raw	B-Application
devices	I-Application
,	O
providing	O
better	O
performance	O
by	O
avoiding	O
the	O
OS	O
filesystem	O
overheads	O
.	O
</s>
<s>
Oracle	B-General_Concept
stores	O
data	O
logically	O
in	O
tablespaces	B-General_Concept
and	O
physically	O
in	O
datafiles	O
associated	O
with	O
the	O
corresponding	O
tablespace	B-General_Concept
.	O
</s>
