Implement aggressive object reference loading for Oracle pre-9.

See http://helma.org/bugs/show_bug.cgi?id=300

src/helma/objectmodel/db/DbMapping.java

@@ -921,6 +921,7 @@ public final class DbMapping implements Updatable {
         // assign to local variable first so we are thread safe
         // (selectString may be reset by other threads)
         String sel = selectString;
+        boolean isOracle = isOracle();
 
         if (rel == null && sel != null) {
             return new StringBuffer(sel);
@@ -962,13 +963,24 @@ public final class DbMapping implements Updatable {
             if (!joins[i].otherType.isRelational()) {
                 continue;
             }
-            s.append("LEFT OUTER JOIN ");
+            if (isOracle) {
-            s.append(joins[i].otherType.getTableName());
+                // generate an old-style oracle left join - see
-            s.append(" AS ");
+                // http://www.praetoriate.com/oracle_tips_outer_joins.htm
-            s.append(Relation.JOIN_PREFIX);
+                s.append(", ");
-            s.append(joins[i].propName);
+                s.append(joins[i].otherType.getTableName());
-            s.append(" ON ");
+                s.append(" ");
-            joins[i].renderJoinConstraints(s);
+                s.append(Relation.JOIN_PREFIX);
+                s.append(joins[i].propName);
+                s.append(" ");
+            } else {
+                s.append("LEFT OUTER JOIN ");
+                s.append(joins[i].otherType.getTableName());
+                s.append(" ");
+                s.append(Relation.JOIN_PREFIX);
+                s.append(joins[i].propName);
+                s.append(" ON ");
+                joins[i].renderJoinConstraints(s, isOracle);
+            }
         }
 
         // cache rendered string for later calls, but only if it wasn't
@@ -1064,6 +1076,37 @@ public final class DbMapping implements Updatable {
         }
     }
 
+    /**
+     * Add constraints to select query string to join object references
+     */
+    public void addJoinConstraints(StringBuffer s, String pre) {
+        boolean isOracle = isOracle();
+        String prefix = pre;
+
+        if (!isOracle) {
+            // constraints have already been rendered by getSelect()
+            return;
+        }
+
+        for (int i = 0; i < joins.length; i++) {
+            if (!joins[i].otherType.isRelational()) {
+                continue;
+            }
+            s.append(prefix);
+            joins[i].renderJoinConstraints(s, isOracle);
+            prefix = " AND ";
+        }
+    }
+
+    /**
+     * Is the database behind this an Oracle db?
+     *
+     * @return true if the dbsource is using an oracle JDBC driver
+     */
+    public boolean isOracle() {
+        return dbSource != null && dbSource.isOracle();
+    }
+
     /**
      *
      *

src/helma/objectmodel/db/DbSource.java

@@ -33,6 +33,7 @@ public class DbSource {
     private String driver;
     protected String user;
     private String password;
+    private boolean isOracle;
     private long lastRead = 0L;
 
     /**
@@ -87,6 +88,7 @@ public class DbSource {
                                                      defaultProps.lastModified());
         url = props.getProperty(name + ".url");
         driver = props.getProperty(name + ".driver");
+        isOracle = driver != null && driver.startsWith("oracle.jdbc.driver");
         Class.forName(driver);
         user = props.getProperty(name + ".user");
         password = props.getProperty(name + ".password");
@@ -118,4 +120,13 @@ public class DbSource {
     public static void setDefaultProps(SystemProperties props) {
         defaultProps = props;
     }
+    
+    /**
+     * Is this an Oracle database?
+     *
+     * @return true if we're using an oracle JDBC driver
+     */
+    public boolean isOracle() {
+        return isOracle;
+    }
 }

src/helma/objectmodel/db/NodeManager.java

@@ -1201,6 +1201,8 @@ public final class NodeManager {
 
                     q.append(") ");
 
+                    dbm.addJoinConstraints(q, " AND ");
+
                     if (rel.groupby != null) {
                         q.append(rel.renderConstraints(home, home.getNonVirtualParent()));
 
@@ -1504,6 +1506,8 @@ public final class NodeManager {
                     q.append(kstr);
                 }
 
+                dbm.addJoinConstraints(q, " AND ");
+
                 if (logSql) {
                     app.logEvent("### getNodeByKey: " + q.toString());
                 }

src/helma/objectmodel/db/Relation.java

@@ -800,6 +800,8 @@ public final class Relation {
             appendFilter(q, nonvirtual, prefix);
         }
 
+        ownType.addJoinConstraints(q, prefix);
+
         if (groupby != null) {
             q.append(" GROUP BY " + groupby);
 
@@ -912,8 +914,11 @@ public final class Relation {
     /**
      *  Render the constraints for this relation for use within
      *  a left outer join select statement for the base object.
+     *
+     * @param select the string buffer to write to
+     * @param isOracle create Oracle pre-9 style left outer join
      */
-    public void renderJoinConstraints(StringBuffer select) {
+    public void renderJoinConstraints(StringBuffer select, boolean isOracle) {
         for (int i = 0; i < constraints.length; i++) {
             select.append(ownType.getTableName());
             select.append(".");
@@ -923,6 +928,11 @@ public final class Relation {
             select.append(propName);
             select.append(".");
             select.append(constraints[i].foreignName);
+            if (isOracle) {
+                // create old oracle style join - see
+                // http://www.praetoriate.com/oracle_tips_outer_joins.htm
+                select.append("(+)");
+            }
             if (i == constraints.length-1) {
                 select.append(" ");
             } else {
@@ -1062,6 +1072,7 @@ public final class Relation {
      */
     public void unsetConstraints(Node parent, INode child) {
         Node home = parent.getNonVirtualParent();
+
         for (int i = 0; i < constraints.length; i++) {
             // don't set groupby constraints since we don't know if the
             // parent node is the base node or a group node