The optimizer does a better job for joins if indexes are missing.

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

@@ -99,7 +99,7 @@ public class Delete extends Prepared {
             condition = condition.optimize(session);
             condition.createIndexConditions(session, tableFilter);
         }
-        PlanItem item = tableFilter.getBestPlanItem(session);
+        PlanItem item = tableFilter.getBestPlanItem(session, 1);
         tableFilter.setPlanItem(item);
         tableFilter.prepare();
     }

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

@@ -176,7 +176,7 @@ public class Update extends Prepared {
                 expressions[i] = expr.optimize(session);
             }
         }
-        PlanItem item = tableFilter.getBestPlanItem(session);
+        PlanItem item = tableFilter.getBestPlanItem(session, 1);
         tableFilter.setPlanItem(item);
         tableFilter.prepare();
     }

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

@@ -105,8 +105,9 @@ public class Plan {
     public double calculateCost(Session session) throws SQLException {
         double cost = 1;
         boolean invalidPlan = false;
+        int level = 1;
         for (TableFilter tableFilter : allFilters) {
-            PlanItem item = tableFilter.getBestPlanItem(session);
+            PlanItem item = tableFilter.getBestPlanItem(session, level++);
             planItems.put(tableFilter, item);
             cost += cost * item.cost;
             setEvaluatable(tableFilter, true);

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

@@ -125,9 +125,10 @@ public class TableFilter implements ColumnResolver {
      * Get the best plan item (index, cost) to use use for the current join order.
      *
      * @param session the session
+     * @param level 1 for the first table in a join, 2 for the second, and so on
      * @return the best plan item
      */
-    public PlanItem getBestPlanItem(Session session) throws SQLException {
+    public PlanItem getBestPlanItem(Session session, int level) throws SQLException {
         PlanItem item;
         if (indexConditions.size() == 0) {
             item = new PlanItem();
@@ -147,10 +148,14 @@ public class TableFilter implements ColumnResolver {
                 }
             }
             item = table.getBestPlanItem(session, masks);
+            // the more index conditions, the earlier the table
+            // to ensure joins without indexes are evaluated:
+            // x (x.a=10); y (x.b=y.b) - see issue 113
+            item.cost -= item.cost * indexConditions.size() / 100 / level;
         }
         if (join != null) {
             setEvaluatable(join);
-            item.setJoinPlan(join.getBestPlanItem(session));
+            item.setJoinPlan(join.getBestPlanItem(session, level));
             // TODO optimizer: calculate cost of a join: should use separate
             // expected row number and lookup cost
             item.cost += item.cost * item.getJoinPlan().cost;

h2/src/test/org/h2/test/test-1.1.txt

 --- special grammar and test cases ---------------------------------------------------------------------------------------------
+create table test(a int, b int) as select x, x from system_range(1, 100);
+> ok
+
+-- the table t1 should be processed first
+explain select * from test t2, test t1 where t1.a=1 and t1.b = t2.b;
+> PLAN
+> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+> SELECT T2.A, T2.B, T1.A, T1.B FROM PUBLIC.TEST T1 /* PUBLIC.TEST_TABLE_SCAN */ /* WHERE T1.A = 1 */ INNER JOIN PUBLIC.TEST T2 /* PUBLIC.TEST_TABLE_SCAN */ ON 1=1 WHERE (T1.A = 1) AND (T1.B = T2.B)
+> rows: 1
+
+explain select * from test t1, test t2 where t1.a=1 and t1.b = t2.b;
+> PLAN
+> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+> SELECT T1.A, T1.B, T2.A, T2.B FROM PUBLIC.TEST T1 /* PUBLIC.TEST_TABLE_SCAN */ /* WHERE T1.A = 1 */ INNER JOIN PUBLIC.TEST T2 /* PUBLIC.TEST_TABLE_SCAN */ ON 1=1 WHERE (T1.A = 1) AND (T1.B = T2.B)
+> rows: 1
+
+drop table test;
+> ok
+
 create table test(id int, constraint pk primary key(id), constraint x unique(id));
 > ok
 
@@ -2513,7 +2532,7 @@ select * from test2, test where test2.name = test.name;
 explain plan for select * from test, test2 where test2.name = test.name;
 > PLAN
 > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-> SELECT TEST.ID, TEST.NAME, TEST2.ID, TEST2.NAME FROM PUBLIC.TEST /* PUBLIC.TEST_TABLE_SCAN */ INNER JOIN PUBLIC.TEST2 /* PUBLIC.TEST2_TABLE_SCAN */ ON 1=1 WHERE TEST2.NAME = CAST(TEST.NAME AS VARCHAR_IGNORECASE(255))
+> SELECT TEST.ID, TEST.NAME, TEST2.ID, TEST2.NAME FROM PUBLIC.TEST2 /* PUBLIC.TEST2_TABLE_SCAN */ INNER JOIN PUBLIC.TEST /* PUBLIC.TEST_TABLE_SCAN */ ON 1=1 WHERE TEST2.NAME = CAST(TEST.NAME AS VARCHAR_IGNORECASE(255))
 > rows: 1
 
 select * from test, test2 where test2.name = test.name;
@@ -6212,7 +6231,7 @@ select * from t1 natural join t2;
 explain select * from t1 natural join t2;
 > PLAN
 > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-> SELECT T1.ID, T1.NAME FROM PUBLIC.T1 /* PUBLIC.T1_TABLE_SCAN */ INNER JOIN PUBLIC.T2 /* PUBLIC.T2_TABLE_SCAN */ ON 1=1 WHERE (PUBLIC.T1.ID = PUBLIC.T2.ID) AND (PUBLIC.T1.NAME = PUBLIC.T2.NAME)
+> SELECT T1.ID, T1.NAME FROM PUBLIC.T2 /* PUBLIC.T2_TABLE_SCAN */ INNER JOIN PUBLIC.T1 /* PUBLIC.T1_TABLE_SCAN */ ON 1=1 WHERE (PUBLIC.T1.ID = PUBLIC.T2.ID) AND (PUBLIC.T1.NAME = PUBLIC.T2.NAME)
 > rows: 1
 
 drop table t1;
@@ -6248,8 +6267,8 @@ select c.*, i.*, l.* from customer c natural join invoice i natural join INVOICE
 
 explain select c.*, i.*, l.* from customer c natural join invoice i natural join INVOICE_LINE l;
 > PLAN
-> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-> SELECT C.CUSTOMERID, C.CUSTOMER_NAME, I.INVOICEID, I.INVOICE_TEXT, L.LINE_ID, L.LINE_TEXT FROM PUBLIC.CUSTOMER C /* PUBLIC.CUSTOMER_TABLE_SCAN */ INNER JOIN PUBLIC.INVOICE I /* PUBLIC.INVOICE_TABLE_SCAN */ ON 1=1 /* WHERE PUBLIC.C.CUSTOMERID = PUBLIC.I.CUSTOMERID */ INNER JOIN PUBLIC.INVOICE_LINE L /* PUBLIC.INVOICE_LINE_TABLE_SCAN */ ON 1=1 WHERE (PUBLIC.C.CUSTOMERID = PUBLIC.I.CUSTOMERID) AND ((PUBLIC.I.CUSTOMERID = PUBLIC.L.CUSTOMERID) AND (PUBLIC.I.INVOICEID = PUBLIC.L.INVOICEID))
+> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+> SELECT C.CUSTOMERID, C.CUSTOMER_NAME, I.INVOICEID, I.INVOICE_TEXT, L.LINE_ID, L.LINE_TEXT FROM PUBLIC.INVOICE I /* PUBLIC.INVOICE_TABLE_SCAN */ INNER JOIN PUBLIC.INVOICE_LINE L /* PUBLIC.INVOICE_LINE_TABLE_SCAN */ ON 1=1 /* WHERE (PUBLIC.I.CUSTOMERID = PUBLIC.L.CUSTOMERID) AND (PUBLIC.I.INVOICEID = PUBLIC.L.INVOICEID) */ INNER JOIN PUBLIC.CUSTOMER C /* PUBLIC.CUSTOMER_TABLE_SCAN */ ON 1=1 WHERE (PUBLIC.C.CUSTOMERID = PUBLIC.I.CUSTOMERID) AND ((PUBLIC.I.CUSTOMERID = PUBLIC.L.CUSTOMERID) AND (PUBLIC.I.INVOICEID = PUBLIC.L.INVOICEID))
 > rows: 1
 
 drop table customer;