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Java > Open Source Codes > org > h2 > table > Plan


1 /*
2  * Copyright 2004-2006 H2 Group. Licensed under the H2 License, Version 1.0 (http://h2database.com/html/license.html).
3  * Initial Developer: H2 Group
4  */
5 package org.h2.table;
6
7 import java.sql.SQLException JavaDoc;
8 import java.util.HashMap JavaDoc;
9
10 import org.h2.engine.Session;
11 import org.h2.expression.Expression;
12 import org.h2.expression.ExpressionVisitor;
13 import org.h2.util.ObjectArray;
14
15 /**
16  * @author Thomas
17  */
18 public class Plan {
19     private TableFilter[] filters;
20     private HashMap JavaDoc planItems = new HashMap JavaDoc();
21     private Expression[] allConditions;
22     private TableFilter[] allFilters;
23
24     public Plan(TableFilter[] filters, int count, Expression condition) {
25         this.filters = new TableFilter[count];
26         System.arraycopy(filters, 0, this.filters, 0, count);
27         ObjectArray allCond = new ObjectArray();
28         ObjectArray allFilt= new ObjectArray();
29         if(condition != null) {
30             allCond.add(condition);
31         }
32         for(int i=0; i<count; i++) {
33             TableFilter f = filters[i];
34             do {
35                 allFilt.add(f);
36                 if(f.getJoinCondition() != null) {
37                     allCond.add(f.getJoinCondition());
38                 }
39                 f = f.getJoin();
40             } while(f != null);
41         }
42         allConditions = new Expression[allCond.size()];
43         allCond.toArray(allConditions);
44         allFilters = new TableFilter[allFilt.size()];
45         allFilt.toArray(allFilters);
46     }
47
48     public PlanItem getItem(TableFilter filter) {
49         return (PlanItem) planItems.get(filter);
50     }
51
52     public TableFilter[] getFilters() {
53         return filters;
54     }
55
56     public void removeUnusableIndexConditions() {
57         for(int i=0; i<allFilters.length; i++) {
58             TableFilter f = allFilters[i];
59             setEvaluatable(f, true);
60             if(i < allFilters.length - 1) {
61                 // the last table doesn't need the optimization,
62 // otherwise the expression is calculated twice unnecessarily
63 // (not that bad but not optimal)
64 f.optimizeFullCondition(false);
65             }
66             f.removeUnusableIndexConditions();
67         }
68         for(int i=0; i<allFilters.length; i++) {
69             TableFilter f = allFilters[i];
70             setEvaluatable(f, false);
71         }
72     }
73
74     public double calculateCost(Session session) throws SQLException JavaDoc {
75         double cost = 1;
76         boolean invalidPlan = false;
77         for (int i = 0; i < allFilters.length; i++) {
78             TableFilter tableFilter = allFilters[i];
79             PlanItem item = tableFilter.getBestPlanItem(session);
80             planItems.put(tableFilter, item);
81             cost += cost * item.cost;
82             setEvaluatable(tableFilter, true);
83             Expression on = tableFilter.getJoinCondition();
84             if(on != null) {
85                 if(!on.isEverything(ExpressionVisitor.EVALUATABLE)) {
86                     invalidPlan = true;
87                     break;
88                 }
89             }
90         }
91         if(invalidPlan) {
92             cost = 1./0.; // Infinity
93 }
94         for (int i = 0; i < allFilters.length; i++) {
95             setEvaluatable(allFilters[i], false);
96         }
97         return cost;
98     }
99
100     private void setEvaluatable(TableFilter filter, boolean b) {
101         for(int j=0; j<allConditions.length; j++) {
102             allConditions[j].setEvaluatable(filter, b);
103         }
104     }
105 }
106
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