| 1 | /* |
| 2 | * Copyright 2006-2012 the original author or authors. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package org.springframework.batch.item.database.support; |
| 18 | |
| 19 | import javax.sql.DataSource; |
| 20 | |
| 21 | import org.springframework.batch.item.database.PagingQueryProvider; |
| 22 | import org.springframework.dao.InvalidDataAccessResourceUsageException; |
| 23 | import org.springframework.jdbc.support.JdbcUtils; |
| 24 | |
| 25 | /** |
| 26 | * Derby implementation of a {@link PagingQueryProvider} using standard SQL:2003 windowing functions. |
| 27 | * These features are supported starting with Apache Derby version 10.4.1.3. |
| 28 | * |
| 29 | * As the OVER() function does not support the ORDER BY clause a sub query is instead used to order the results |
| 30 | * before the ROW_NUM restriction is applied |
| 31 | * |
| 32 | * @author Thomas Risberg |
| 33 | * @author David Thexton |
| 34 | * @author Michael Minella |
| 35 | * @since 2.0 |
| 36 | */ |
| 37 | public class DerbyPagingQueryProvider extends SqlWindowingPagingQueryProvider { |
| 38 | |
| 39 | private static final String MINIMAL_DERBY_VERSION = "10.4.1.3"; |
| 40 | |
| 41 | @Override |
| 42 | public void init(DataSource dataSource) throws Exception { |
| 43 | super.init(dataSource); |
| 44 | String version = JdbcUtils.extractDatabaseMetaData(dataSource, "getDatabaseProductVersion").toString(); |
| 45 | if (!isDerbyVersionSupported(version)) { |
| 46 | throw new InvalidDataAccessResourceUsageException("Apache Derby version " + version + " is not supported by this class, Only version " + MINIMAL_DERBY_VERSION + " or later is supported"); |
| 47 | } |
| 48 | } |
| 49 | |
| 50 | // derby version numbering is M.m.f.p [ {alpha|beta} ] see http://db.apache.org/derby/papers/versionupgrade.html#Basic+Numbering+Scheme |
| 51 | private boolean isDerbyVersionSupported(String version) { |
| 52 | String[] minimalVersionParts = MINIMAL_DERBY_VERSION.split("\\."); |
| 53 | String[] versionParts = version.split("[\\. ]"); |
| 54 | for (int i = 0; i < minimalVersionParts.length; i++) { |
| 55 | int minimalVersionPart = Integer.valueOf(minimalVersionParts[i]); |
| 56 | int versionPart = Integer.valueOf(versionParts[i]); |
| 57 | if (versionPart < minimalVersionPart) { |
| 58 | return false; |
| 59 | } else if (versionPart > minimalVersionPart) { |
| 60 | return true; |
| 61 | } |
| 62 | } |
| 63 | return true; |
| 64 | } |
| 65 | |
| 66 | @Override |
| 67 | protected String getOrderedQueryAlias() { |
| 68 | return "TMP_ORDERED"; |
| 69 | } |
| 70 | |
| 71 | @Override |
| 72 | protected String getOverClause() { |
| 73 | return ""; |
| 74 | } |
| 75 | |
| 76 | @Override |
| 77 | protected String getOverSubstituteClauseStart() { |
| 78 | return " FROM (SELECT " + getSelectClause(); |
| 79 | } |
| 80 | |
| 81 | @Override |
| 82 | protected String getOverSubstituteClauseEnd() { |
| 83 | return " ) AS " + getOrderedQueryAlias(); |
| 84 | } |
| 85 | |
| 86 | } |