Experimental feature to support nested joins.

h2/src/main/org/h2/command/dml/Select.java

@@ -866,7 +866,12 @@ public class Select extends Query {
             if (on != null) {
                 if (!on.isEverything(ExpressionVisitor.EVALUATABLE)) {
                     if (SysProperties.NESTED_JOINS) {
-                        int testCanSupport;
+                        f.removeJoinCondition();
+                        // need to check that all added are bound to a table
+                        on = on.optimize(session);
+                        if (!f.isJoinOuter() && !f.isJoinOuterIndirect()) {
+                            addCondition(on);
+                        }
                     } else {
                         if (f.isJoinOuter()) {
                             // this will check if all columns exist - it may or may not throw an exception
@@ -874,11 +879,11 @@ public class Select extends Query {
                             // it is not supported even if the columns exist
                             throw DbException.get(ErrorCode.UNSUPPORTED_OUTER_JOIN_CONDITION_1, on.getSQL());
                         }
+                        f.removeJoinCondition();
+                        // need to check that all added are bound to a table
+                        on = on.optimize(session);
+                        addCondition(on);
                     }
-                    f.removeJoinCondition();
-                    // need to check that all added are bound to a table
-                    on = on.optimize(session);
-                    addCondition(on);
                 }
             }
             on = f.getFilterCondition();

h2/src/main/org/h2/expression/ExpressionColumn.java

@@ -246,6 +246,9 @@ public class ExpressionColumn extends Expression {
             // or if this columns belongs to a 'higher level' query and is
             // therefore just a parameter
             if (SysProperties.NESTED_JOINS) {
+                if (visitor.getQueryLevel() < this.queryLevel) {
+                    return true;
+                }
                 if (getTableFilter() == null) {
                     return false;
                 }

h2/src/main/org/h2/table/TableFilter.java

@@ -34,10 +34,10 @@ import org.h2.value.Value;
  */
 public class TableFilter implements ColumnResolver {
     private static final int BEFORE_FIRST = 0, FOUND = 1, AFTER_LAST = 2, NULL_ROW = 3;
+    protected Session session;
     private final Table table;
     private final Select select;
     private String alias;
-    private Session session;
     private Index index;
     private int scanCount;
     private boolean evaluatable;
@@ -78,10 +78,15 @@ public class TableFilter implements ColumnResolver {
     private TableFilter join;
 
     /**
-     * Whether this table is an outer join.
+     * Whether this is an outer join.
      */
     private boolean joinOuter;
 
+    /**
+     * Whether this is a direct or indirect (nested) outer join
+     */
+    protected boolean joinOuterIndirect;
+
     /**
      * The nested joined table (if there is one).
      */
@@ -505,6 +510,13 @@ public class TableFilter implements ColumnResolver {
             }
             nestedJoin = filter;
             filter.joinOuter = outer;
+            if (outer) {
+                visit(new TableFilterVisitor() {
+                    public void accept(TableFilter f) {
+                        f.joinOuterIndirect = true;
+                    }
+                });
+            }
             if (on != null) {
                 filter.mapAndAddFilter(on);
             }
@@ -540,6 +552,10 @@ public class TableFilter implements ColumnResolver {
         on.mapColumns(this, 0);
         addFilterCondition(on, true);
         on.createIndexConditions(session, this);
+        if (nestedJoin != null) {
+            on.mapColumns(nestedJoin, 0);
+            on.createIndexConditions(session, nestedJoin);
+        }
         if (join != null) {
             join.mapAndAddFilter(on);
         }
@@ -550,7 +566,7 @@ public class TableFilter implements ColumnResolver {
     }
 
     /**
-     * Check if this is an outer joined table.
+     * Whether this is an outer joined table.
      *
      * @return true if it is
      */
@@ -558,6 +574,15 @@ public class TableFilter implements ColumnResolver {
         return joinOuter;
     }
 
+    /**
+     * Whether this is indirectly an outer joined table (nested within an inner join).
+     *
+     * @return true if it is
+     */
+    public boolean isJoinOuterIndirect() {
+        return joinOuterIndirect;
+    }
+
     /**
      * Get the query execution plan text to use for this table filter.
      *
@@ -583,7 +608,7 @@ public class TableFilter implements ColumnResolver {
             } while (n != null);
             buff.append(") ON ");
             if (joinCondition == null) {
-                // need to have a ON expression, 
+                // need to have a ON expression,
                 // otherwise the nesting is unclear
                 buff.append("1=1");
             } else {
@@ -731,7 +756,7 @@ public class TableFilter implements ColumnResolver {
      * @param b the new flag
      */
     public void setEvaluatable(TableFilter filter, boolean b) {
-        setEvaluatable(b);
+        filter.setEvaluatable(b);
         if (filterCondition != null) {
             filterCondition.setEvaluatable(filter, b);
         }

h2/src/test/org/h2/test/TestAll.java

@@ -305,6 +305,8 @@ java org.h2.test.TestAll timer
         // System.setProperty("h2.lobInDatabase", "true");
         // System.setProperty("h2.analyzeAuto", "100");
         // System.setProperty("h2.nestedJoins", "true");
+        // System.setProperty("h2.optimizeOr", "true");
+        // System.setProperty("h2.dropRestrict", "true");
 
         int speedup;
         // System.setProperty("h2.syncMethod", "");

h2/src/test/org/h2/test/db/TestNestedJoins.java

@@ -37,7 +37,7 @@ public class TestNestedJoins extends TestBase {
     public static void main(String... a) throws Exception {
         System.setProperty("h2.nestedJoins", "true");
         TestBase test = TestBase.createCaller().init();
-        test.config.traceTest = true;
+        // test.config.traceTest = true;
         test.test();
     }
 
@@ -62,17 +62,15 @@ public class TestNestedJoins extends TestBase {
         } catch (Exception e) {
             // database not installed - ok
         }
+
         // Derby doesn't work currently
-        deleteDerby();
-        try {
-            Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
-            Connection c2 = DriverManager.getConnection("jdbc:derby:" + getBaseDir() + "/derby/test;create=true", "sa", "sa");
-            dbs.add(c2.createStatement());
-        } catch (Exception e) {
-            // database not installed - ok
-        }
-        // if (dbs.size() == 0) {
-        //      return;
+        // deleteDerby();
+        // try {
+        //     Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
+        //     Connection c2 = DriverManager.getConnection("jdbc:derby:" + getBaseDir() + "/derby/test;create=true", "sa", "sa");
+        //     dbs.add(c2.createStatement());
+        // } catch (Exception e) {
+        //     // database not installed - ok
         // }
         String shortest = null;
         Throwable shortestEx = null;
@@ -121,12 +119,11 @@ public class TestNestedJoins extends TestBase {
                 execute(sql);
             } catch (Throwable e) {
                 if (e instanceof SQLException) {
-                    SQLException se = (SQLException) e;
                     trace(sql);
-                    int todoFail;
-int test;
-                    System.out.println(se);
-                    System.out.println("  " + sql);
+                    fail(sql);
+                    // SQLException se = (SQLException) e;
+                    // System.out.println(se);
+                    // System.out.println("  " + sql);
                 }
                 if (e != null) {
                     if (shortest == null || sql.length() < shortest.length()) {
@@ -243,6 +240,18 @@ int test;
         ResultSet rs;
         String sql;
 
+        /*
+        create table test(id int primary key);
+        explain select * from test a left outer join (test c) on a.id = c.id;
+        -- expected: uses the primary key index
+        */
+        stat.execute("create table test(id int primary key)");
+        rs = stat.executeQuery("explain select * from test a left outer join (test c) on a.id = c.id");
+        assertTrue(rs.next());
+        sql = rs.getString(1);
+        assertTrue(sql.indexOf("PRIMARY_KEY") >= 0);
+        stat.execute("drop table test");
+
         /*
         create table t1(a int, b int);
         create table t2(a int, b int);
@@ -315,6 +324,18 @@ int test;
         assertFalse(rs.next());
         stat.execute("drop table a, b, c");
 
+        /*
+        drop table a, b, c;
+        create table a(x int);
+        create table b(x int);
+        create table c(x int, y int);
+        insert into a values(1), (2);
+        insert into b values(3);
+        insert into c values(1, 3);
+        insert into c values(4, 5);
+        explain select * from a left outer join (b left outer join c on b.x = c.y) on a.x = c.x;
+        select * from a left outer join (b left outer join c on b.x = c.y) on a.x = c.x;
+         */
         stat.execute("create table a(x int)");
         stat.execute("create table b(x int)");
         stat.execute("create table c(x int, y int)");
@@ -490,7 +511,6 @@ int test;
         r.setSkipRemarks(true);
         sql = r.readStatement();
         sql = sql.replaceAll("\\n", " ");
-        // sql = sql.replaceAll("\\/\\*.*\\*\\/", "");
         while (sql.indexOf("  ") >= 0) {
             sql = sql.replaceAll("  ", " ");
         }

h2/src/test/org/h2/test/test-1.2.txt

@@ -885,9 +885,6 @@ select * from ((test d1 inner join test d2 on d1.id = d2.id) inner join test d3
 > -- -- -- --
 > rows: 0
 
-select * from dual a left join dual b on b.x=(select max(x) from dual);
-> exception
-
 drop table test;
 > ok