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1
5 package org.h2.command.ddl;
6
7 import java.sql.SQLException  ;
8
9 import org.h2.command.Prepared;
10 import org.h2.engine.Constants;
11 import org.h2.engine.Database;
12 import org.h2.engine.DbObject;
13 import org.h2.engine.Session;
14 import org.h2.result.LocalResult;
15 import org.h2.table.Column;
16 import org.h2.table.Table;
17 import org.h2.table.TableData;
18 import org.h2.util.ObjectArray;
19
20 public class Analyze extends DefineCommand {
21
22 private int sampleRows = Constants.SELECTIVITY_ANALYZE_SAMPLE_ROWS;
23
24 public Analyze(Session session) {
25 super(session);
26 }
27
28 public int update() throws SQLException {
29 session.commit();
30 Database db = session.getDatabase();
31 session.getUser().checkAdmin();
32 ObjectArray tables = db.getAllSchemaObjects(DbObject.TABLE_OR_VIEW);
33 for(int i=0; i<tables.size(); i++) {
35 Table table = (Table) tables.get(i);
36 if(!(table instanceof TableData)) {
37 continue;
38 }
39 Column[] columns = table.getColumns();
40 StringBuffer buff = new StringBuffer ();
41 buff.append("SELECT ");
42 for(int j=0; j<columns.length; j++) {
43 if(j>0) {
44 buff.append(", ");
45 }
46 buff.append("SELECTIVITY(");
47 buff.append(columns[j].getSQL());
48 buff.append(")");
49 }
50 buff.append(" FROM ");
51 buff.append(table.getSQL());
52 if(sampleRows > 0) {
53 buff.append(" LIMIT 1 SAMPLE_SIZE ");
54 buff.append(sampleRows);
55 }
56 String sql = buff.toString();
57 Prepared command = session.prepare(sql);
58 LocalResult result = command.query(0);
59 result.next();
60 for(int j=0; j<columns.length; j++) {
61 int selectivity = result.currentRow()[j].getInt();
62 columns[j].setSelectivity(selectivity);
63 }
64 db.update(session, table);
65 }
66 return 0;
67 }
68
69 public void setTop(int top) {
70 this.sampleRows = top;
71 }
72
73 }
74 |
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