1. Session – 7 DATA HANDLING – DISTRIBUTION AND TRANSFORMATION Matakuliah: M0184 / Pengolahan Data Distribusi Tahun: 2005 Versi:

2. OBJECTIVES DATA ALLOCATION THE DATA PLACEMENT AND ALLOCATION PROBLEM SEMANTIC APPROACH FOR DATA ALLOCATION

3. DATA ALLOCATION An essential aspect of handling distributed data arises when we are deciding how to distributed the data around the sites in order to take advantage of the “natural” parallelism of execution inherent in the distributed system. Providing automatic methods of transforming access to data which are written in global query language into local DBMS

4. The Data Placement and Allocation Problem This problem is concerned with ensuring that the data objects are well placed with respect to other objects with which they are related “Well Placedness”  if data object O1 and O2 are required consecutively in a particular query, place them near to each other. Dispersing files efficiently around network Splitting records up, so that the most “busy” parts are allocated the best performing facilities

5. DATA ALLOCATION (EXAMPLE) Single Relation Case : (1,p)(1,q)(1,r)(1,s) (2,q)(2,r)(2,s)(2,p) (3,r)(3,s)(3,p)(3,q) (4,s)(4,p)(4,q)(4,r) Get all tuples with a “1” in the first position ? Alternative placement as follows : (1,p)(1,r)(3,p)(3,r) (1,q)(1,s)(3,q)(3,s) (2,p)(2,r)(4,p)(4,r) (2,q)(2,s)(4,q)(4,s)

6. DATA ALLOCATION (EXAMPLE) Multi Relation Case : (a,p)(p,1) (a,q)(p,2)(a,r)(p,3)(a,s)(p,4) (b,q)(q,2) (b,r)(q,3)(b,s)(q,4)(b,p)(q,1) (c,r)(r,3) (c,s)(r,4)(c,p)(r,1)(c,q)(r,2) (d,s)(s,4) (d,p)(s,1)(d,q)(s,2)(d,r)(s,3) ===== ===== ===== ===== ===== ===== ===== ====== R1R2R1R2R1R2R1R2 Get all R2 tuples with a “1” in column 2 which match R1 tuples with an “a” in column 1 Alternative placement as follows : (a,p)(p,1) (c,p)(p,3)(a,r)(r,1)(c,r)(r,3) (b,p)(p,2) (d,q)(p,4)(b,r)(r,2)(d,r)(r,4) (a,q)(q,1) (c,p)(q,3)(a,s)(s,1)(c,s)(s,3) (b,q)(q,2) (d,q)(q,4)(b,s)(s,2)(d,s)(s,4) ===== ===== ===== ===== ===== ===== ===== ====== R1R2R1R2R1R2R1R2

7. Semantic Approach to the Problem Optimizing the placement and allocation data without considering the requirements of any quantitative cost model directly The goal : to split a global database up into fragments to maximize the efficiency of query execution

8. Semantic Approach to the Problem Example of qualitative approach  to have equi-JOIN on a primary key or a foreign key in SQL Query SELECT doctor-name, patient-name FROM Doctor, Patient WHERE Doctor.age = patient.age