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1
5 package org.h2.command.dml;
6
7 import java.sql.SQLException  ;
8 import java.util.HashSet ;
9
10 import org.h2.command.Prepared;
11 import org.h2.engine.Session;
12 import org.h2.expression.Alias;
13 import org.h2.expression.Expression;
14 import org.h2.expression.ExpressionColumn;
15 import org.h2.expression.ExpressionVisitor;
16 import org.h2.expression.Parameter;
17 import org.h2.message.Message;
18 import org.h2.result.LocalResult;
19 import org.h2.result.SortOrder;
20 import org.h2.table.ColumnResolver;
21 import org.h2.table.TableFilter;
22 import org.h2.util.ObjectArray;
23 import org.h2.value.Value;
24
25 public abstract class Query extends Prepared {
26
27 protected Expression limit, offset;
28 protected int sampleSize;
29
30 private int lastLimit;
31 private long lastEvaluated;
32 private LocalResult lastResult;
33 private Value[] lastParameters;
34
35 abstract LocalResult queryWithoutCache(int limit) throws SQLException ;
36
37 public Query(Session session) {
38 super(session);
39 }
40
41 public boolean isQuery() {
42 return true;
43 }
44
45 public boolean isTransactional() {
46 return true;
47 }
48
49 public final boolean sameResultAsLast(Session session, Value[] params, Value[] lastParams, long lastEvaluated) throws SQLException {
50 for(int i=0; i<params.length; i++) {
51 if(!session.getDatabase().areEqual(lastParams[i], params[i])) {
52 return false;
53 }
54 }
55 if(!isEverything(ExpressionVisitor.DETERMINISTIC) || !isEverything(ExpressionVisitor.INDEPENDENT)) {
56 return false;
57 }
58 if(getMaxDataModificationId() > lastEvaluated) {
59 return false;
60 }
61 return true;
62 }
63
64 public final Value[] getParameterValues() throws SQLException {
65 ObjectArray list = getParameters();
66 if(list == null) {
67 list = new ObjectArray();
68 }
69 Value[] params = new Value[list.size()];
70 for(int i=0; i<list.size(); i++) {
71 Value v = ((Parameter) list.get(i)).getParamValue();
72 params[i] = v;
73 }
74 return params;
75 }
76
77 public final LocalResult query(int limit) throws SQLException {
78 if(!session.getDatabase().getOptimizeReuseResults()) {
79 return queryWithoutCache(limit);
80 }
81 Value[] params = getParameterValues();
82 long now = session.getDatabase().getModificationDataId();
83 if(lastResult != null && limit == lastLimit) {
84 if(sameResultAsLast(session, params, lastParameters, lastEvaluated)) {
85 lastResult = lastResult.createShallowCopy(session);
86 lastResult.reset();
87 return lastResult;
88 }
89 }
90 lastParameters = params;
91 lastResult = queryWithoutCache(limit);
92 this.lastEvaluated = now;
93 lastLimit = limit;
94 return lastResult;
95 }
96
97 protected SortOrder initOrder(ObjectArray expressions, ObjectArray orderList, int visible, boolean mustBeInResult) throws SQLException {
98 int[] index = new int[orderList.size()];
99 int[] sortType = new int[orderList.size()];
100 int originalLength = expressions.size();
101 for(int i=0; i<orderList.size(); i++) {
102 SelectOrderBy o = (SelectOrderBy) orderList.get(i);
103 int idx;
104 if(o.expression != null) {
105 Expression e = o.expression;
106 boolean isAlias = false;
110 idx = expressions.size();
111 if(e instanceof ExpressionColumn) {
112 ExpressionColumn ecol = (ExpressionColumn)e;
113 String alias = ecol.getOriginalAliasName();
114 String col = ecol.getOriginalColumnName();
115 for(int j=0; j<visible; j++) {
116 boolean found = false;
117 Expression ec = (Expression) expressions.get(j);
118 if(ec instanceof ExpressionColumn) {
119 ExpressionColumn c = (ExpressionColumn) ec;
120 found = col.equals(c.getColumnName());
121 if(alias != null && found) {
122 found = alias.equals(c.getOriginalAliasName());
123 }
124 } else if(!(ec instanceof Alias)) {
125 continue;
126 } else if(col.equals(ec.getAlias())) {
127 found = true;
128 } else {
129 Expression ec2 = ec.getNonAliasExpression();
130 if(ec2 instanceof ExpressionColumn) {
131 ExpressionColumn c2 = (ExpressionColumn) ec2;
132 found = col.equals(c2.getColumnName());
133 }
134 }
135 if(found) {
136 idx = j;
137 isAlias = true;
138 break;
139 }
140 }
141 }
142 if(!isAlias) {
143 if(mustBeInResult) {
144 throw Message.getSQLException(Message.ORDER_BY_NOT_IN_RESULT, e.getSQL());
145 }
146 expressions.add(e);
147 }
148 } else {
149 idx = o.column;
150 if(idx >= originalLength) {
151 throw Message.getSQLException(Message.ORDER_BY_NOT_IN_RESULT, "index " + idx);
152 }
153 }
154 index[i] = idx;
155 int type = o.descending ? SortOrder.DESCENDING : SortOrder.ASCENDING;
156 if(o.nullsFirst) {
157 type += SortOrder.NULLS_FIRST;
158 } else if(o.nullsLast) {
159 type += SortOrder.NULLS_LAST;
160 }
161 sortType[i] = type;
162 }
163 return new SortOrder(session.getDatabase(), index, sortType);
164 }
165
166 public void setOffset(Expression offset) {
167 this.offset = offset;
168 }
169
170 public void setLimit(Expression limit) {
171 this.limit = limit;
172 }
173
174 public abstract void init() throws SQLException ;
175 public abstract ObjectArray getExpressions();
176 public abstract double getCost();
177 public abstract HashSet getTables();
178 public abstract void setOrder(ObjectArray order);
179 public abstract void setForUpdate(boolean forUpdate);
180 public abstract int getColumnCount();
181 public abstract void mapColumns(ColumnResolver resolver, int level) throws SQLException ;
182 public abstract void setEvaluatable(TableFilter tableFilter, boolean b);
183 public abstract void addGlobalCondition(Expression expr, int columnId, int comparisonType) throws SQLException ;
184 public abstract void setDistinct(boolean b);
185
186 public void setSampleSize(int sampleSize) {
187 this.sampleSize = sampleSize;
188 }
189
190 public final long getMaxDataModificationId() {
191 ExpressionVisitor visitor = ExpressionVisitor.get(ExpressionVisitor.SET_MAX_DATA_MODIFICATION_ID);
192 isEverything(visitor);
193 return visitor.getMaxDataModificationId();
194 }
195
196 public abstract boolean isEverything(ExpressionVisitor visitor);
197
198 public final boolean isEverything(int expressionVisitorType) {
199 ExpressionVisitor visitor = ExpressionVisitor.get(expressionVisitorType);
200 return isEverything(visitor);
201 }
202
203 }
204 |
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