Database Reference
In-Depth Information
Table 9. Result of FTS union, intersection & minus operations on FTS relations R and S
FTS relation
R
FTS relation
S
Name
Subject
Grade
μ
r
source
Name
Subject
Grade
μ
r
source
Gupta
DBMS
.5/C
.50
DB
1
Datta
OOPS
.63/A
.63
DB
2
Raja
OOPS
B
1.0
DB
2
Sonu
Graph
.73/A
.73
DB
2
Datta
OOPS
.65/A
.65
DB
1
gupta
DBMS
.5/C
.50
DB
1
fs
sameDB
È
. ,8 5
fs
any
DB
È
. ,8 5
R
S
R
S
μ
r
μ
r
Name
Subject
Grade
source
Name
Subject
Grade
source
Gupta
DBMS
.5/C
.55
DB
1
Gupta
DBMS
.5/C
.50
DB
1
Raja
OOPS
B
1.0
DB
2
Raja
OOPS
B
1.0
DB
2
Datta
OOPS
.65/A
.65
DB
1
Datta
OOPS
.65/A
.65
*
Datta
OOPS
.63/A
.63
DB
2
fs
sameDB
Ç
. ,8 5
fs
any
DB
Ç
. ,8 5
R
S
R
S
DB
1
DB
1
Gupta
DBMS
.5/C
.50
Gupta
DBMS
.5/C
.50
Datta
OOPS
.65/A
.65
*
fs
sameDB
-
. ,8 5
fs
any
DB
-
. ,8 5
R
S
R
S
Raja
OOPS
B
1.0
DB
2
Raja
OOPS
B
1.0
DB
2
Datta
OOPS
.65/A
.65
DB
1
Many real world problems involve imprecise and ambiguous information rather than crisp information.
Recent trends in the database paradigm are to incorporate fuzzy sets to tackle imprecise and ambiguous
information of real world problems. Fuzzy query processing in multidatabases have been extensively
studied, however, the same has rarely been addressed for fuzzy multidatabases. In this chapter we have
made an attempt to extend the SQL to formulate a global fuzzy query on a fuzzy multidatabase under
FTS relational model discussed earlier. We have also provided architecture for distributed fuzzy query
processing with a strategy for fuzzy query decomposition and optimization.
Assumptions
Our system configuration basically consists of one global site and a number of local sites. One of the
local sites can be the global site, in which case we save a data communication cost for the site and the
global site. Each local site maintains its own data management system that support FSQL (Galindo,
Medina, Cubero and Garca, 2001; Galindo, Medina, Pons and Cubero, 1998) and is independent of other
sites. A user communicates only with the global site. A global fuzzy query using FTS-SQL is entered
