/*
* Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.command.ddl;
import org.h2.command.CommandInterface;
import org.h2.command.Prepared;
import org.h2.engine.Database;
import org.h2.engine.Right;
import org.h2.engine.Session;
import org.h2.result.ResultInterface;
import org.h2.table.Column;
import org.h2.table.RegularTable;
import org.h2.table.Table;
import org.h2.util.StatementBuilder;
/**
* This class represents the statement
* ANALYZE
*/
public class Analyze extends DefineCommand {
/**
* The sample size.
*/
private int sampleRows;
public Analyze(Session session) {
super(session);
sampleRows = session.getDatabase().getSettings().analyzeSample;
}
public int update() {
session.commit(true);
session.getUser().checkAdmin();
Database db = session.getDatabase();
for (Table table : db.getAllTablesAndViews(false)) {
analyzeTable(session, table, sampleRows, true);
}
return 0;
}
/**
* Analyze this table.
*
* @param session the session
* @param table the table
* @param sample the number of sample rows
* @param manual whether the command was called by the user
*/
public static void analyzeTable(Session session, Table table, int sample, boolean manual) {
if (!(table instanceof RegularTable) || table.isHidden() || session == null) {
return;
}
if (!manual) {
if (session.getDatabase().isSysTableLocked()) {
return;
}
if (table.hasSelectTrigger()) {
return;
}
}
if (table.isTemporary() && !table.isGlobalTemporary()
&& session.findLocalTempTable(table.getName()) == null) {
return;
}
if (table.isLockedExclusively() && !table.isLockedExclusivelyBy(session)) {
return;
}
if (!session.getUser().hasRight(table, Right.SELECT)) {
return;
}
if (session.getCancel() != 0) {
// if the connection is closed and there is something to undo
return;
}
Database db = session.getDatabase();
StatementBuilder buff = new StatementBuilder("SELECT ");
Column[] columns = table.getColumns();
for (Column col : columns) {
buff.appendExceptFirst(", ");
buff.append("SELECTIVITY(").append(col.getSQL()).append(')');
}
buff.append(" FROM ").append(table.getSQL());
if (sample > 0) {
buff.append(" LIMIT 1 SAMPLE_SIZE ").append(sample);
}
String sql = buff.toString();
Prepared command = session.prepare(sql);
ResultInterface result = command.query(0);
result.next();
for (int j = 0; j < columns.length; j++) {
int selectivity = result.currentRow()[j].getInt();
columns[j].setSelectivity(selectivity);
}
if (manual) {
db.update(session, table);
} else {
Session s = db.getSystemSession();
if (s != session) {
// if the current session is the system session
// (which is the case if we are within a trigger)
// then we can't update the statistics because
// that would unlock all locked objects
db.update(s, table);
s.commit(true);
}
}
}
public void setTop(int top) {
this.sampleRows = top;
}
public int getType() {
return CommandInterface.ANALYZE;
}
}