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1 package com.quadcap.sql;
2
3
40
41 import java.io.ByteArrayOutputStream  ;
42 import java.io.Externalizable ;
43 import java.io.IOException ;
44 import java.io.ObjectInput ;
45 import java.io.ObjectOutput ;
46
47 import java.util.Enumeration ;
48 import java.util.Hashtable ;
49
50 import java.util.Vector ;
51
52 import java.sql.SQLException ;
53
54 import com.quadcap.sql.io.ObjectInputStream;
55 import com.quadcap.sql.io.ObjectOutputStream;
56
57 import com.quadcap.sql.file.ByteUtil;
58
59 import com.quadcap.util.Debug;
60 import com.quadcap.util.Util;
61
62
68 public class DistinctCursor extends BC_Cursor {
69 Cursor sourceCursor;
70 Vector orderBy = null;
71 TempTable tempTable;
72 boolean distinct = true;
73
74
77 public DistinctCursor(Session session, Cursor cursor) throws SQLException {
78 super(session, null, null);
79 this.sourceCursor = cursor;
80 addColumns(session, cursor);
81 }
82
83 public final void checkCursor() throws SQLException , IOException {
84 if (bc == null) {
85 try {
86 makeTempTable();
87 } finally {
88 try {
89 sourceCursor.close();
90 } catch (Throwable t) {
91 } finally {
92 sourceCursor = null;
93 }
94 }
95 }
96 }
97
98
99 private void makeTempTable() throws IOException , SQLException {
100 int size = getColumnCount();
101 if (orderBy == null) {
102 if (distinct) {
103 tempTable = new TempTable(session, new Key(size), null);
104 } else {
105 tempTable = new TempTable(session, new Key(1), new int[0]);
106 }
107 } else {
108 tempTable = makeObTemp();
109 }
110 tempTable.addRows(sourceCursor);
111 row = new LazyRow(size);
112 bc = tempTable.getCursor();
113 }
114
115 TempTable makeObTemp() throws SQLException , IOException {
116 int[] map = new int[getColumnCount()];
117 boolean[] rmap = new boolean[map.length+1];
118 boolean[] asc = new boolean[map.length];
119 for (int i = 0; i < orderBy.size(); i++) {
120 OrderElement elem = (OrderElement)orderBy.elementAt(i);
121 int num = elem.getColumn();
122 if (num < 0) {
123 String name = elem.getColName();
124 Column col = getColumn(name);
125 if (col == null) {
126 throw new SQLException ("Bad column name: " + name);
127 }
128 num = col.getColumn();
129 elem.setColumn(num);
130 }
131 map[i] = num;
132 rmap[num] = true;
133 asc[i] = elem.isAscending();
134 }
135 int cnt = orderBy.size();
136 for (int i = 1; i < rmap.length; i++) {
137 if (!rmap[i]) {
138 map[cnt] = i;
139 asc[cnt] = true;
140 cnt++;
141 }
142 }
143 Key compare = new Key(asc);
144 return new TempTable(session, compare, map);
145 }
146
147 public void setOrder(Vector v) {
148 this.orderBy = v;
149 }
150
151 public void setDistinct(boolean b) {
152 this.distinct = b;
153 }
154
155 public long getCurrentRowId() throws SQLException {
156 return ByteUtil.getLong(bc.getValBuf(), 1);
157 }
158
159 public void fetchCurrentRow() throws SQLException , IOException {
160 tempTable.getRow(bc.getValBuf(), row);
161 rowValid = true;
162 }
163
164
167 public void close() throws SQLException {
168 try {
169 super.close();
170 } finally {
171 try {
172 if (sourceCursor != null) sourceCursor.close();
173 } finally {
174 sourceCursor = null;
175 try {
176 if (tempTable != null) tempTable.release();
177 } catch (IOException ex) {
178 throw DbException.wrapThrowable(ex);
179 } finally {
180 tempTable = null;
181 }
182 }
183 }
184 }
185
186 public String toString() {
188 return super.toString() + "\n\t[source cursor = " + sourceCursor + "]\n";
189 }
190 }
192 |
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