Adds DB2 support

Provides the files and enum constants for Spring Cloud Task
to work with a DB2 database.

spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/Db2PagingQueryProvider.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.task.repository.database.support;
+
+import org.springframework.data.domain.Pageable;
+
+/**
+ * IBM DB2 implementation of a {@link org.springframework.cloud.task.repository.database.PagingQueryProvider} using database
+ * specific features.
+ * 
+ * @author Thomas Schuettel
+ */
+public class Db2PagingQueryProvider extends AbstractSqlPagingQueryProvider {
+
+	@Override
+	public String getPageQuery(Pageable pageable) {
+		int offset = pageable.getOffset() + 1;
+		return generateRowNumSqlQueryWithNesting(getSelectClause(), false,
+				"TMP_ROW_NUM BETWEEN " + offset + " AND " + (offset + pageable.getPageSize()));
+	}
+
+	private String generateRowNumSqlQueryWithNesting(String selectClause, boolean remainingPageQuery,
+			String rowNumClause) {
+		StringBuilder sql = new StringBuilder();
+		sql.append("SELECT ").append(selectClause).append(" FROM (SELECT ").append(selectClause).append(", ")
+				.append("ROW_NUMBER() OVER() as TMP_ROW_NUM");
+		sql.append(" FROM (SELECT ").append(selectClause).append(" FROM ").append(this.getFromClause());
+		SqlPagingQueryUtils.buildWhereClause(this, remainingPageQuery, sql);
+		sql.append(" ORDER BY ").append(SqlPagingQueryUtils.buildSortClause(this));
+		sql.append(")) WHERE ").append(rowNumClause);
+
+		return sql.toString();
+	}
+
+}

spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/SqlPagingQueryProviderFactoryBean.java

@@ -16,7 +16,7 @@
 
 package org.springframework.cloud.task.repository.database.support;
 
-
+import static org.springframework.cloud.task.repository.support.DatabaseType.DB2;
 import static org.springframework.cloud.task.repository.support.DatabaseType.HSQL;
 import static org.springframework.cloud.task.repository.support.DatabaseType.H2;
 import static org.springframework.cloud.task.repository.support.DatabaseType.MYSQL;
@@ -68,6 +68,7 @@ public class SqlPagingQueryProviderFactoryBean implements FactoryBean<PagingQuer
 		providers.put(POSTGRES, new PostgresPagingQueryProvider());
 		providers.put(ORACLE, new OraclePagingQueryProvider());
 		providers.put(SQLSERVER, new SqlServerPagingQueryProvider());
+		providers.put(DB2, new Db2PagingQueryProvider());
 	}
 
 	/**

spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/DatabaseType.java

@@ -40,7 +40,8 @@ public enum DatabaseType {
 	ORACLE("Oracle"),
 	MYSQL("MySQL"),
 	POSTGRES("PostgreSQL"),
-	SQLSERVER("Microsoft SQL Server");
+	SQLSERVER("Microsoft SQL Server"),
+	DB2("DB2");
 
 	private static final Map<String, DatabaseType> dbNameMap;
 

spring-cloud-task-core/src/main/resources/org/springframework/cloud/task/schema-db2.sql

@@ -0,0 +1,26 @@
+
+CREATE TABLE TASK_EXECUTION  (
+	TASK_EXECUTION_ID BIGINT  NOT NULL PRIMARY KEY ,
+	START_TIME TIMESTAMP DEFAULT NULL ,
+	END_TIME TIMESTAMP DEFAULT NULL ,
+	TASK_NAME  VARCHAR(100) ,
+	EXIT_CODE INTEGER ,
+	EXIT_MESSAGE VARCHAR(2500) ,
+	LAST_UPDATED TIMESTAMP
+);
+
+CREATE TABLE TASK_EXECUTION_PARAMS  (
+	TASK_EXECUTION_ID BIGINT NOT NULL ,
+	TASK_PARAM VARCHAR(2500) ,
+	constraint TASK_EXEC_PARAMS_FK foreign key (TASK_EXECUTION_ID)
+	references TASK_EXECUTION(TASK_EXECUTION_ID)
+) ;
+
+CREATE TABLE TASK_TASK_BATCH (
+  TASK_EXECUTION_ID BIGINT NOT NULL ,
+  JOB_EXECUTION_ID BIGINT NOT NULL ,
+	constraint TASK_EXEC_BATCH_FK foreign key (TASK_EXECUTION_ID)
+	references TASK_EXECUTION(TASK_EXECUTION_ID)
+) ;
+
+CREATE SEQUENCE TASK_SEQ AS BIGINT START WITH 0 MINVALUE 0 MAXVALUE 9223372036854775807 NOCACHE NOCYCLE;

spring-cloud-task-docs/src/main/asciidoc/getting-started.adoc

@@ -29,6 +29,7 @@ While you can begin developing a task without a database (the status of the task
  as part of the task repository's updates), for production environments, you'll want to
 utilize a supported database.  Below is a list of the ones currently supported:
 
+- DB2
 - H2
 - HSQLDB
 - MySql