1. Instructors: Winston Hsu, Hao-Hua Chu Fall 2010
HW6: Sort-Merge Join
Instructors: Winston Hsu, Hao-Hua Chu
Fall 2010

2. Architecture of a DBMS Query Query Optimization and Execution
Relation Operators(Join)
File and Access Methods
Buffer Management
Disk Space Management DB

3. Sort-Merge Join

4. Example Sort by sname Get the first tuples Merge sid sname 31 A 28 E22 36 C 44 D
sid
sname 31 A 22 36 C 44 D 28 E
sname
BID A
112
168 B
101 C
118
sname
BID C
118 B
112 A
168
101
Sort by sname
sid
sname
BID 31 A
112
168 22 36 C
118
Get the first tuples
Merge

5. Some APIs Sort constructor(… outfile …) HeapFile constructor
Outfile : Name of sorted heapfile should be distinct
HeapFile constructor
HeapFile->openScan()
Followed by scan->getNext() and get the firstRecord
tupleCmp() : compare tuples
Scan->position()
Position the scan cursor to the record with the given rid.

6. Other
Output format:
If there are any questions, you can post them on ptt.cc / CSIE_DBMS, or mail to:
Deadline: 23:59 Jan 12 (Wednesday), 2011 if =
,then write
recA
recA
recA
recA

7. Heapfile
“Database Management Systems, Third Edition” by Ramakrishnan and Gehrke