Issue #643: H2 doesn't use index when I use IN and EQUAL in one query

h2/src/docsrc/html/changelog.html

@@ -21,6 +21,8 @@ Change Log
 
 <h2>Next Version (unreleased)</h2>
 <ul>
+<li>Issue #643: H2 doesn't use index when I use IN and EQUAL in one query 
+</li>
 <li>Reset transaction start timestamp on ROLLBACK
 </li>
 <li>Issue #632: CREATE OR REPLACE VIEW creates incorrect columns names

h2/src/main/org/h2/index/IndexCursor.java

@@ -131,9 +131,9 @@ public class IndexCursor implements Cursor {
                 if (isIntersects) {
                     intersects = getSpatialSearchRow(intersects, columnId, v);
                 }
-                if (isStart || isEnd) {
-                    // an X=? condition will produce less rows than
-                    // an X IN(..) condition
+                // An X=? condition will produce less rows than
+                // an X IN(..) condition, unless the X IN condition can use the index.
+                if ((isStart || isEnd) && !canUseIndexFor(inColumn)) {
                     inColumn = null;
                     inList = null;
                     inResult = null;
@@ -176,6 +176,10 @@ public class IndexCursor implements Cursor {
             // only one IN(..) condition can be used at the same time
             return false;
         }
+        return canUseIndexFor(column);
+    }
+
+    private boolean canUseIndexFor(Column column) {
         // The first column of the index must match this column,
         // or it must be a VIEW index (where the column is null).
         // Multiple IN conditions with views are not supported, see

h2/src/test/org/h2/test/scripts/TestScript.java

@@ -80,6 +80,7 @@ public class TestScript extends TestBase {
         }
         reconnectOften = !config.memory && config.big;
         testScript("testScript.sql");
+        testScript("query-optimisations.sql");
         testScript("commands-dml-script.sql");
         testScript("commands-dml-create-view.sql");
         for (String s : new String[] { "array", "bigint", "binary", "blob",

h2/src/test/org/h2/test/scripts/query-optimisations.sql

+-- Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
+-- and the EPL 1.0 (http://h2database.com/html/license.html).
+-- Initial Developer: H2 Group
+--
+
+create table person(firstname varchar, lastname varchar);
+> ok
+
+create index person_1 on person(firstname, lastname);
+> ok
+
+insert into person select convert(x,varchar) as firstname, (convert(x,varchar) || ' last') as lastname from system_range(1,100);
+> update count: 100
+
+-- Issue #643: verify that when using an index, we use the IN part of the query, if that part of the query
+-- can directly use the index.
+-- 
+explain analyze SELECT * FROM person WHERE firstname IN ('FirstName1', 'FirstName2') AND lastname='LastName1';
+> PLAN
+> -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+> SELECT PERSON.FIRSTNAME, PERSON.LASTNAME FROM PUBLIC.PERSON /* PUBLIC.PERSON_1: FIRSTNAME IN('FirstName1', 'FirstName2') AND LASTNAME = 'LastName1' */ /* scanCount: 1 */ WHERE (FIRSTNAME IN('FirstName1', 'FirstName2')) AND (LASTNAME = 'LastName1')
+> rows: 1