Initial DB2Luw9Platform using row_number() for row limiting sql

platforms/db2/src/main/java/io/ebean/platform/db2/DB2Luw9Platform.java

@@ -0,0 +1,15 @@
+package io.ebean.platform.db2;
+
+import io.ebean.annotation.Platform;
+
+/**
+ * DB2 platform for Linux/Unix/Windows version 9.x.
+ */
+public class DB2Luw9Platform extends BaseDB2Platform {
+  public DB2Luw9Platform() {
+    super();
+    this.platform = Platform.DB2LUW; // TODO: Add a DB2LUW9
+    this.basicSqlLimiter = new DB2RowNumberBasicLimiter();
+    this.sqlLimiter = new DB2RowNumberSqlLimiter();
+  }
+}

platforms/db2/src/main/java/io/ebean/platform/db2/DB2RowNumberBasicLimiter.java

@@ -0,0 +1,31 @@
+package io.ebean.platform.db2;
+
+import io.ebean.config.dbplatform.BasicSqlLimiter;
+
+/**
+ * Row limiter for Oracle 9,10,11 using rownum.
+ */
+final class DB2RowNumberBasicLimiter implements BasicSqlLimiter {
+
+  @Override
+  public String limit(String dbSql, int firstRow, int maxRows) {
+    if (firstRow < 1 && maxRows < 1) {
+      return dbSql;
+    }
+    StringBuilder sb = new StringBuilder(60 + dbSql.length());
+    int lastRow = maxRows;
+    if (lastRow > 0) {
+      lastRow += firstRow;
+    }
+    sb.append("select * from (select row_number() over() rn, a.* from (");
+    sb.append(dbSql).append(") a ");
+    if (lastRow > 0) {
+      sb.append(" where rn <= ").append(lastRow);
+    }
+    sb.append(") ");
+    if (firstRow > 0) {
+      sb.append(" where rn_ > ").append(firstRow);
+    }
+    return sb.toString();
+  }
+}

platforms/db2/src/main/java/io/ebean/platform/db2/DB2RowNumberSqlLimiter.java

@@ -0,0 +1,38 @@
+package io.ebean.platform.db2;
+
+import io.ebean.config.dbplatform.SqlLimitRequest;
+import io.ebean.config.dbplatform.SqlLimitResponse;
+import io.ebean.config.dbplatform.SqlLimiter;
+
+
+final class DB2RowNumberSqlLimiter implements SqlLimiter {
+
+  @Override
+  public SqlLimitResponse limit(SqlLimitRequest request) {
+    String dbSql = request.getDbSql();
+
+    StringBuilder sb = new StringBuilder(60 + dbSql.length());
+    int firstRow = request.getFirstRow();
+    int lastRow = request.getMaxRows();
+    if (lastRow > 0) {
+      lastRow += firstRow;
+    }
+
+    sb.append("select * from (select row_number() over() rn, a.* from (select ");
+    if (request.isDistinct()) {
+      sb.append("distinct ");
+    }
+    sb.append(dbSql).append(") a ");
+    if (lastRow > 0) {
+      sb.append(" where rn <= ").append(lastRow);
+    }
+    sb.append(") ");
+    if (firstRow > 0) {
+      sb.append(" where rn > ").append(firstRow);
+    }
+
+    String sql = request.getDbPlatform().completeSql(sb.toString(), request.getOrmQuery());
+    return new SqlLimitResponse(sql);
+  }
+
+}

platforms/db2/src/main/java/io/ebean/platform/db2/Db2PlatformProvider.java

@@ -39,6 +39,9 @@ public class Db2PlatformProvider implements DatabasePlatformProvider {
     if (name.equals("db2luw")) {
       return new DB2LuwPlatform();
     }
+    if (name.equals("db2luw9")) {
+      return new DB2Luw9Platform();
+    }
     throw new IllegalArgumentException("Unknown DB2 platform, expecting db2luw/db2zos/db2fori but got "+ name);
   }