Database Reference
In-Depth Information
Table 8. Result of FTS join operation to join the FTS relations Emp & Dept from Table-5.
fs
sameDB
fs
sameDB
fs
anyDB
fs
anyDB
(
Emp
Dept
)
(
Emp
Dept
)
p
A
p
A
DD
DD
,.
5
Name HoD
=
,.
5
,.
5
Name HoD
=
,.
5
Dname
Staff
Fund
μ
r
source
Dname
Staff
Fund
μ
r
source
Chem
Null
.5/low
.50
DB
1
Chem
Null
.5/low
.50
DB
1
Chem
15
.5/mod
.50
DB
2
Chem
15
.5/mod
.50
*
Eco
10
.5/mod
.50
DB
2
Chem
Null
.5/low
.50
*
Chem
15
.5/mod
.50
DB
2
Where A={Dname, Staff, Fund}
Eco
Null
.5/mod
.50
*
Eco
10
.5/mod
.50
DB
2
fs
to indicate if projected attributes from different export
fuzzy databases sharing the same fuzzy attributes should be merged or not. s
merge
() produces
∧
for
resultant tuples that have multiple sources. Original source values are not maintained because (1) the
source attribute values should be atomic, (2) By maintaining set of values for source information, it is
not possible to tell the exact source of each individual attribute for a given FTS relation. (see Table 7).
A flag (
sameDB
or
anyDB
) is attached to
p
Definition: FTS
join
(
D
fs
)
(
)
≥
µ
(
a a
,
) min
=
µ
(
a
),
µ
(
a
)
β
=
(
)
fs
sameDB
T
R
S
R
R
S
S
T
=
R
S
a a
,
,
µ
(
a a
,
)
1
DD
α β
1
,
R
S
T
R
S
∧
p a a s
(
,
,
,
s
)
∧ =
(
s
s
=
s
≠ ∗
)
1
α
R
S
a
a
a
a
R
S
R
S
(
)
≥ ∧
a a
,
,
µ
(
a a
,
),
µ
(
a a
,
) min
µ
(
a
),
µ
(
a
)
β
=
R
S
T
R
S
fs
anyDB
T
R
S
R
R
S
S
T
=
R
S
=
2
(
)
{
}
2
DD
α β
2
,
p a a s
(
,
,
,
s
)
∧ =
(
s
s
=
s
≠ ∗
)
smerge
s
,
s
α
R
S
a
a
a
a
a
a
R
S
R
S
R
S
where
p
α
is a conjunction of fuzzy predicates which may include the source related predicates. It can be
observed that the operator
D
fs
anyDB
α β
,
produces a
∧
source value for its resultant fuzzy tuple whenever it
joins two fuzzy tuples from different sources, whereas the operator
D
fs
sameDB
α β
retains the original non-
∧
,
source values.
fs
Definition:FTS
union
( )
∪
(
)
≥
µ
( .
t A t A
,
. )
≥ ∧
α µ
( . ) max
t A
=
µ
( . ),
t A
µ
(
t A
. )
fs
sameDB
EQ
R
T
T
R R
(
)
1
1
T
= ∪
R
S
=
t A
.
,
µ
( . ), .
t A t s
β
∧
( .
t s
=
t
≠ ∗ ∨
)
µ
( .
t A t A
,
. )
≥ ∧
α µ
( . ) max
t A
=
α β
,
1
T
R
EQ
S
T
1
1
(
)
≥ ∧
µ
( . ),
t A
µ
( . )
t A
β
(
t s
.
= ≠ ∗
t
)
T
S
S
S
1
fs
anyDB
f
f
f
f
f
f
T
= ∪
R
S
=
( .
t A
,
µ
( . ),
t A smerge
(
π
(
σ
(
R
∪
S
)))) .
t A
∈
((
π
R
)
∪
(
π
S
))
α β
,
s
,
β
µ
( , . )
A t A
β
A
,
α β
,
α β
,
A
,
α β
,
2
T
EQ
1
