#278 - SqlQuery setFirstRow fail - modify SQL using LIMIT/OFFSET etc to support firstRows/maxRows

src/main/java/com/avaje/ebean/config/dbplatform/BasicSqlAnsiLimiter.java

@@ -0,0 +1,24 @@
+package com.avaje.ebean.config.dbplatform;
+
+/**
+ * Adds ANSI based OFFSET FETCH NEXT clauses to a SQL query.
+ */
+public class BasicSqlAnsiLimiter implements BasicSqlLimiter {
+
+  @Override
+  public String limit(String dbSql, int firstRow, int maxRows) {
+
+    StringBuilder sb = new StringBuilder(50 + dbSql.length());
+
+    sb.append(dbSql);
+    if (firstRow > 0) {
+      sb.append(" ").append("offset");
+      sb.append(" ").append(firstRow).append(" rows");
+    }
+    if (maxRows > 0) {
+      sb.append(" fetch next ").append(maxRows).append(" rows only");
+    }
+    return sb.toString();
+  }
+
+}

src/main/java/com/avaje/ebean/config/dbplatform/BasicSqlLimitOffset.java

@@ -0,0 +1,36 @@
+package com.avaje.ebean.config.dbplatform;
+
+/**
+ * Adds LIMIT OFFSET clauses to a SQL query.
+ */
+public class BasicSqlLimitOffset implements BasicSqlLimiter {
+
+  /**
+   * LIMIT keyword.
+   */
+  private static final String LIMIT = "limit";
+
+  /**
+   * OFFSET keyword.
+   */
+  private static final String OFFSET = "offset";
+
+  @Override
+  public String limit(String dbSql, int firstRow, int maxRows) {
+
+    StringBuilder sb = new StringBuilder(50 + dbSql.length());
+
+    sb.append(dbSql);
+
+    if (maxRows > 0) {
+      sb.append(" ").append(LIMIT);
+      sb.append(" ").append(maxRows);
+    }
+    if (firstRow > 0) {
+      sb.append(" ").append(OFFSET).append(" ");
+      sb.append(firstRow);
+    }
+    return sb.toString();
+  }
+
+}

src/main/java/com/avaje/ebean/config/dbplatform/BasicSqlLimiter.java

@@ -0,0 +1,12 @@
+package com.avaje.ebean.config.dbplatform;
+
+/**
+ * Simple SQL limiter for use with SqlQuery.
+ */
+public interface BasicSqlLimiter {
+
+  /**
+   * Add basic offset/limit clause to SqlQuery query.
+   */
+  String limit(String dbSql, int firstRow, int maxRows);
+}

src/main/java/com/avaje/ebean/config/dbplatform/DatabasePlatform.java

@@ -71,6 +71,11 @@ public class DatabasePlatform {
    */
   protected SqlLimiter sqlLimiter = new LimitOffsetSqlLimiter();
 
+  /**
+   * Limit/offset support for SqlQuery only.
+   */
+  protected BasicSqlLimiter basicSqlLimiter = new BasicSqlLimitOffset();
+
   /**
    * Mapping of JDBC to Database types.
    */
@@ -454,6 +459,13 @@ public class DatabasePlatform {
     return sqlLimiter;
   }
 
+  /**
+   * Return the BasicSqlLimiter for limit/offset of SqlQuery queries.
+   */
+  public BasicSqlLimiter getBasicSqlLimiter() {
+    return basicSqlLimiter;
+  }
+
   /**
    * Set the DB TRUE literal (from the registered boolean ScalarType)
    */

src/main/java/com/avaje/ebean/config/dbplatform/OraclePlatform.java

@@ -18,6 +18,7 @@ public class OraclePlatform extends DatabasePlatform {
     this.maxConstraintNameLength = 30;
     this.dbEncrypt = new OracleDbEncrypt();
     this.sqlLimiter = new RownumSqlLimiter();
+    this.basicSqlLimiter = new BasicSqlAnsiLimiter();
     this.platformDdl = new Oracle10Ddl(this);
     this.historySupport = new OracleDbHistorySupport();
 

src/main/java/com/avaje/ebeaninternal/server/core/RelationalQueryRequest.java

@@ -31,8 +31,6 @@ import java.util.List;
  */
 public final class RelationalQueryRequest {
 
-  private static final int GLOBAL_ROW_LIMIT = Integer.valueOf(System.getProperty("ebean.query.globallimit", "1000000"));
-
   private static final Logger logger = LoggerFactory.getLogger(RelationalQueryRequest.class);
 
   private final SpiSqlQuery query;
@@ -212,7 +210,18 @@ public final class RelationalQueryRequest {
       // convert any named parameters if required
       sql = BindParamsParser.parse(bindParams, sql);
     }
-    this.sql = sql;
+    this.sql = limitOffset(sql);
+  }
+
+  private String limitOffset(String sql) {
+
+    int firstRow = query.getFirstRow();
+    int maxRows = query.getMaxRows();
+    if (firstRow > 0 || maxRows > 0) {
+      return ebeanServer.getDatabasePlatform().getBasicSqlLimiter()
+          .limit(query.getQuery(), firstRow, maxRows);
+    }
+    return sql;
   }
 
   /**
@@ -250,13 +259,6 @@ public final class RelationalQueryRequest {
 
   }
 
-  /**
-   * Return the maxRows allowed to fetch.
-   */
-  public int getMaxRows() {
-    return query.getMaxRows() >= 1 ? query.getMaxRows() : GLOBAL_ROW_LIMIT;
-  }
-
   /**
    * Return the SQL executed for this query.
    */

src/main/java/com/avaje/ebeaninternal/server/query/DefaultRelationalQueryEngine.java

@@ -74,19 +74,9 @@ public class DefaultRelationalQueryEngine implements RelationalQueryEngine {
     try {
       request.executeSql(binder);
 
-      int maxRows = request.getMaxRows();
-
-      int loadRowCount = 0;
-
       List<SqlRow> rows = new ArrayList<SqlRow>();
-
       while (request.next()) {
         rows.add(readRow(request));
-        loadRowCount++;
-        if (loadRowCount == maxRows) {
-          // break, as we have hit the max rows to fetch...
-          break;
-        }
       }
 
       logSummary(request, startTime);