KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > objectstyle > cayenne > dba > oracle > OracleSelectTranslator


1 /* ====================================================================
2  *
3  * The ObjectStyle Group Software License, version 1.1
4  * ObjectStyle Group - http://objectstyle.org/
5  *
6  * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
7  * of the software. All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  * notice, this list of conditions and the following disclaimer.
15  *
16  * 2. Redistributions in binary form must reproduce the above copyright
17  * notice, this list of conditions and the following disclaimer in
18  * the documentation and/or other materials provided with the
19  * distribution.
20  *
21  * 3. The end-user documentation included with the redistribution, if any,
22  * must include the following acknowlegement:
23  * "This product includes software developed by independent contributors
24  * and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
25  * Alternately, this acknowlegement may appear in the software itself,
26  * if and wherever such third-party acknowlegements normally appear.
27  *
28  * 4. The names "ObjectStyle Group" and "Cayenne" must not be used to endorse
29  * or promote products derived from this software without prior written
30  * permission. For written permission, email
31  * "andrus at objectstyle dot org".
32  *
33  * 5. Products derived from this software may not be called "ObjectStyle"
34  * or "Cayenne", nor may "ObjectStyle" or "Cayenne" appear in their
35  * names without prior written permission.
36  *
37  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40  * DISCLAIMED. IN NO EVENT SHALL THE OBJECTSTYLE GROUP OR
41  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48  * SUCH DAMAGE.
49  * ====================================================================
50  *
51  * This software consists of voluntary contributions made by many
52  * individuals and hosted on ObjectStyle Group web site. For more
53  * information on the ObjectStyle Group, please see
54  * <http://objectstyle.org/>.
55  */
56
57 package org.objectstyle.cayenne.dba.oracle;
58
59 import java.lang.reflect.Method JavaDoc;
60 import java.sql.PreparedStatement JavaDoc;
61 import java.sql.Statement JavaDoc;
62
63 import org.apache.log4j.Level;
64 import org.apache.log4j.Logger;
65 import org.objectstyle.cayenne.access.QueryLogger;
66 import org.objectstyle.cayenne.access.trans.SelectTranslator;
67
68 /**
69  * Select translator that implements Oracle-specific optimizations.
70  *
71  * @author Andrei Adamchik
72  */
73 public class OracleSelectTranslator extends SelectTranslator {
74
75     private static Logger logObj = Logger.getLogger(OracleSelectTranslator.class);
76
77     private static boolean testedDriver;
78     private static boolean useOptimizations;
79     private static Method JavaDoc statementSetRowPrefetch;
80
81     private static final Object JavaDoc[] rowPrefetchArgs = new Object JavaDoc[] {
82         new Integer JavaDoc(100)
83     };
84
85     /**
86      * Determines if we can use Oracle optimizations. If yes, configure this object to use
87      * them via reflection.
88      */
89     private static final synchronized void testDriver(Statement JavaDoc st) {
90         if (testedDriver) {
91             return;
92         }
93
94         // invalid call.. give it another chance later
95 if (st == null) {
96             return;
97         }
98
99         testedDriver = true;
100
101         try {
102             // search for matching methods in class and its superclasses
103
104             Class JavaDoc[] args2 = new Class JavaDoc[] {
105                 Integer.TYPE
106             };
107             statementSetRowPrefetch = st.getClass().getMethod("setRowPrefetch", args2);
108
109             useOptimizations = true;
110         }
111         catch (Exception JavaDoc ex) {
112             useOptimizations = false;
113             statementSetRowPrefetch = null;
114
115             StringBuffer JavaDoc buf = new StringBuffer JavaDoc();
116             buf
117                     .append("Unknown Oracle statement type: [")
118                     .append(st.getClass().getName())
119                     .append("]. No Oracle optimizations applied.");
120
121             logObj.info(buf.toString());
122         }
123     }
124
125     /**
126      * Translates internal query into PreparedStatement, applying Oracle optimizations if
127      * possible.
128      */
129     public PreparedStatement JavaDoc createStatement(Level logLevel) throws Exception JavaDoc {
130         String JavaDoc sqlStr = createSqlString();
131         QueryLogger.logQuery(logLevel, sqlStr, values);
132         PreparedStatement JavaDoc stmt = connection.prepareStatement(sqlStr);
133
134         initStatement(stmt);
135
136         if (!testedDriver) {
137             testDriver(stmt);
138         }
139
140         if (useOptimizations) {
141             // apply Oracle optimization of the statement
142
143             // Performance tests conducted by Arndt (bug #699966) show
144 // that using explicit "defineColumnType" slows things down,
145 // so this is disabled now
146
147             // 1. name result columns
148 /*
149              * List columns = getColumns(); int len = columns.size(); Object[] args = new
150              * Object[2]; for (int i = 0; i < len; i++) { DbAttribute attr = (DbAttribute)
151              * columns.get(i); args[0] = new Integer(i + 1); args[1] = new
152              * Integer(attr.getType()); statementDefineColumnType.invoke(stmt, args); }
153              */
154
155             // 2. prefetch bigger batches of rows
156 // [This optimization didn't give any measurable performance
157 // increase. Keeping it for the future research]
158 // Note that this is done by statement,
159 // instead of Connection, since we do not want to mess
160 // with Connection that is potentially used by
161 // other people.
162 statementSetRowPrefetch.invoke(stmt, rowPrefetchArgs);
163         }
164
165         return stmt;
166     }
167 }
Popular Tags