url - Universität zu Lübeck

122 CHAPTER 6. THE INDEX SELECTION PROBLEM
Figure 6.7: Test 3: Long-running evaluation of the ISP tool that optimizes the
database to a permanently changing workload.
The pseudo code for this test scenario including the delta algorithm is presented
below.
1 /∗∗
2 ∗ Pseudo code f o r scenario 3:
3 ∗ This method creates , modifies and
4 ∗ executes a workload continuously .
5 ∗ The ISP Tool is called to optimize
6 ∗ the workload ’ s execution time .
7 ∗/
9 int counter = 0;
10 int ispFrequency = 30;
11 double queryModifyRatio = 0.75;
12 int workloadSize = 25;
13 Workload w =
14 createRandomWorkload ( workloadSize )
16 while ( true ) {
17 // create new database Operation
18 Operation op = new Operation ( ) ;
19 op . path = createRandomPathExpr ( ) ;
20 op . type = getType ( queryModifyRatio ) ;
22 // swap op with random op from w
23 int index =
24 ( int )random . nextDouble ( ) ∗workloadSize ;
25 w[ index ] = op ;
27 // execute and log the workload
28 w. log ( ) ;
29 w. execute ( ) ;
31 // c a l l ISP t o o l each ispFreq ’ th run
32 i f ( counter % ispFrequency == 0)
33 ispTool . createSuitableIndexes (w) ;
35 counter++;
36 }