Merge pull request #211 from svladykin/batchview2

Batched index lookups for sub-query

h2/src/main/org/h2/command/Command.java

@@ -68,6 +68,11 @@ public abstract class Command implements CommandInterface {
     @Override
     public abstract boolean isQuery();
 
+    /**
+     * Prepare join batching.
+     */
+    public abstract void prepareJoinBatch();
+
     /**
      * Get the list of parameters.
      *

h2/src/main/org/h2/command/CommandContainer.java

@@ -7,6 +7,8 @@ package org.h2.command;
 
 import java.util.ArrayList;
 import org.h2.api.DatabaseEventListener;
+import org.h2.command.dml.Explain;
+import org.h2.command.dml.Query;
 import org.h2.expression.Parameter;
 import org.h2.expression.ParameterInterface;
 import org.h2.result.ResultInterface;
@@ -44,6 +46,23 @@ public class CommandContainer extends Command {
         return prepared.isQuery();
     }
 
+    @Override
+    public void prepareJoinBatch() {
+        if (session.isJoinBatchEnabled()) {
+            prepareJoinBatch(prepared);
+        }
+    }
+
+    private static void prepareJoinBatch(Prepared prepared) {
+        if (prepared.isQuery()) {
+            if (prepared.getType() == CommandInterface.SELECT) {
+                ((Query) prepared).prepareJoinBatch();
+            } else if (prepared.getType() == CommandInterface.EXPLAIN) {
+                prepareJoinBatch(((Explain) prepared).getCommand());
+            }
+        }
+    }
+
     private void recompileIfRequired() {
         if (prepared.needRecompile()) {
             // TODO test with 'always recompile'
@@ -65,6 +84,7 @@ public class CommandContainer extends Command {
             }
             prepared.prepare();
             prepared.setModificationMetaId(mod);
+            prepareJoinBatch();
         }
     }
 

h2/src/main/org/h2/command/CommandList.java

@@ -44,6 +44,11 @@ class CommandList extends Command {
         return updateCount;
     }
 
+    @Override
+    public void prepareJoinBatch() {
+        command.prepareJoinBatch();
+    }
+
     @Override
     public ResultInterface query(int maxrows) {
         ResultInterface result = command.query(maxrows);

h2/src/main/org/h2/command/ddl/AlterTableAddConstraint.java

@@ -294,6 +294,9 @@ public class AlterTableAddConstraint extends SchemaCommand {
     }
 
     private static Index getUniqueIndex(Table t, IndexColumn[] cols) {
+        if (t.getIndexes() == null) {
+            return null;
+        }
         for (Index idx : t.getIndexes()) {
             if (canUseUniqueIndex(idx, t, cols)) {
                 return idx;
@@ -303,6 +306,9 @@ public class AlterTableAddConstraint extends SchemaCommand {
     }
 
     private static Index getIndex(Table t, IndexColumn[] cols, boolean moreColumnOk) {
+        if (t.getIndexes() == null) {
+            return null;
+        }
         for (Index idx : t.getIndexes()) {
             if (canUseIndex(idx, t, cols, moreColumnOk)) {
                 return idx;

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

@@ -40,6 +40,10 @@ public class Explain extends Prepared {
         this.command = command;
     }
 
+    public Prepared getCommand() {
+        return command;
+    }
+
     @Override
     public void prepare() {
         command.prepare();

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

@@ -24,11 +24,6 @@ public class NoOperation extends Prepared {
         return 0;
     }
 
-    @Override
-    public boolean isQuery() {
-        return false;
-    }
-
     @Override
     public boolean isTransactional() {
         return true;

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

@@ -71,6 +71,18 @@ public abstract class Query extends Prepared {
         super(session);
     }
 
+    /**
+     * Check if this is a UNION query.
+     * 
+     * @return {@code true} if this is a UNION query
+     */
+    public abstract boolean isUnion();
+
+    /**
+     * Prepare join batching.
+     */
+    public abstract void prepareJoinBatch();
+
     /**
      * Execute the query without checking the cache. If a target is specified,
      * the results are written to it, and the method returns null. If no target

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

@@ -9,7 +9,6 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
-
 import org.h2.api.ErrorCode;
 import org.h2.api.Trigger;
 import org.h2.command.CommandInterface;
@@ -36,6 +35,7 @@ import org.h2.result.SortOrder;
 import org.h2.table.Column;
 import org.h2.table.ColumnResolver;
 import org.h2.table.IndexColumn;
+import org.h2.table.JoinBatch;
 import org.h2.table.Table;
 import org.h2.table.TableFilter;
 import org.h2.util.New;
@@ -87,6 +87,11 @@ public class Select extends Query {
         super(session);
     }
 
+    @Override
+    public boolean isUnion() {
+        return false;
+    }
+
     /**
      * Add a table to the query.
      *
@@ -945,6 +950,30 @@ public class Select extends Query {
         isPrepared = true;
     }
 
+    @Override
+    public void prepareJoinBatch() {
+        ArrayList<TableFilter> list = New.arrayList();
+        TableFilter f = getTopTableFilter();
+        do {
+            if (f.getNestedJoin() != null) {
+                // we do not support batching with nested joins 
+                return;
+            }
+            list.add(f);
+            f = f.getJoin();
+        } while (f != null);
+        TableFilter[] fs = list.toArray(new TableFilter[list.size()]);
+        // prepare join batch
+        JoinBatch jb = null;
+        for (int i = fs.length - 1; i >= 0; i--) {
+            jb = fs[i].prepareJoinBatch(jb, fs, i);
+        }
+    }
+
+    public JoinBatch getJoinBatch() {
+        return getTopTableFilter().getJoinBatch();
+    }
+
     @Override
     public double getCost() {
         return cost;

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

@@ -7,7 +7,6 @@ package org.h2.command.dml;
 
 import java.util.ArrayList;
 import java.util.HashSet;
-
 import org.h2.api.ErrorCode;
 import org.h2.command.CommandInterface;
 import org.h2.engine.Session;
@@ -72,6 +71,17 @@ public class SelectUnion extends Query {
         this.left = query;
     }
 
+    @Override
+    public boolean isUnion() {
+        return true;
+    }
+
+    @Override
+    public void prepareJoinBatch() {
+        left.prepareJoinBatch();
+        right.prepareJoinBatch();
+    }
+
     public void setUnionType(int type) {
         this.unionType = type;
     }

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

@@ -497,6 +497,15 @@ public class Set extends Prepared {
             database.setRowFactory(rowFactory);
             break;
         }
+        case SetTypes.BATCH_JOINS: {
+            int value = getIntValue();
+            if (value != 0 && value != 1) {
+                throw DbException.getInvalidValueException("BATCH_JOINS",
+                        getIntValue());
+            }
+            session.setJoinBatchEnabled(value == 1);
+            break;
+        }
         default:
             DbException.throwInternalError("type="+type);
         }

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

@@ -228,6 +228,11 @@ public class SetTypes {
      */
     public static final int ROW_FACTORY = 43;
 
+    /**
+     * The type of SET BATCH_JOINS statement.
+     */
+    public static final int BATCH_JOINS = 44;
+
     private static final ArrayList<String> TYPES = New.arrayList();
 
     private SetTypes() {
@@ -280,6 +285,7 @@ public class SetTypes {
         list.add(QUERY_STATISTICS, "QUERY_STATISTICS");
         list.add(QUERY_STATISTICS_MAX_ENTRIES, "QUERY_STATISTICS_MAX_ENTRIES");
         list.add(ROW_FACTORY, "ROW_FACTORY");
+        list.add(BATCH_JOINS, "BATCH_JOINS");
     }
 
     /**

h2/src/main/org/h2/engine/Session.java

@@ -30,12 +30,14 @@ import org.h2.mvstore.db.TransactionStore.Change;
 import org.h2.mvstore.db.TransactionStore.Transaction;
 import org.h2.result.LocalResult;
 import org.h2.result.Row;
+import org.h2.result.SortOrder;
 import org.h2.schema.Schema;
 import org.h2.store.DataHandler;
 import org.h2.store.InDoubtTransaction;
 import org.h2.store.LobStorageFrontend;
 import org.h2.table.SubQueryInfo;
 import org.h2.table.Table;
+import org.h2.table.TableFilter;
 import org.h2.util.New;
 import org.h2.util.SmallLRUCache;
 import org.h2.value.Value;
@@ -115,6 +117,7 @@ public class Session extends SessionWithState {
     private int parsingView;
     private volatile SmallLRUCache<Object, ViewIndex> viewIndexCache;
     private HashMap<Object, ViewIndex> subQueryIndexCache;
+    private boolean joinBatchEnabled;
 
     /**
      * Temporary LOBs from result sets. Those are kept for some time. The
@@ -148,12 +151,25 @@ public class Session extends SessionWithState {
         this.currentSchemaName = Constants.SCHEMA_MAIN;
     }
 
+    public void setJoinBatchEnabled(boolean joinBatchEnabled) {
+        this.joinBatchEnabled = joinBatchEnabled;
+    }
+
+    public boolean isJoinBatchEnabled() {
+        return joinBatchEnabled;
+    }
+
     public Row createRow(Value[] data, int memory) {
         return database.createRow(data, memory);
     }
 
-    public void setSubQueryInfo(SubQueryInfo subQueryInfo) {
-        this.subQueryInfo = subQueryInfo;
+    public void pushSubQueryInfo(int[] masks, TableFilter[] filters, int filter,
+            SortOrder sortOrder) {
+        subQueryInfo = new SubQueryInfo(subQueryInfo, masks, filters, filter, sortOrder);
+    }
+
+    public void popSubQueryInfo() {
+        subQueryInfo = subQueryInfo.getUpper();
     }
 
     public SubQueryInfo getSubQueryInfo() {
@@ -492,6 +508,7 @@ public class Session extends SessionWithState {
             // we can't reuse sub-query indexes, so just drop the whole cache
             subQueryIndexCache = null;
         }
+        command.prepareJoinBatch();
         if (queryCache != null) {
             if (command.isCacheable()) {
                 queryCache.put(sql, command);

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

@@ -15,7 +15,8 @@ import org.h2.result.SearchRow;
  * method {@link #isBatchFull()}} will return {@code true} or there are no more
  * search rows to add. Then method {@link #find()} will be called to execute batched lookup.
  * Note that a single instance of {@link IndexLookupBatch} can be reused for multiple 
- * sequential batched lookups.
+ * sequential batched lookups, moreover it can be reused for multiple queries for
+ * the same prepared statement.
  * 
  * @see Index#createLookupBatch(org.h2.table.TableFilter)
  * @author Sergi Vladykin
@@ -26,9 +27,11 @@ public interface IndexLookupBatch {
      * 
      * @param first the first row, or null for no limit
      * @param last the last row, or null for no limit
+     * @return {@code false} if this search row pair is known to produce no results
+     *          and thus the given row pair was not added
      * @see Index#find(TableFilter, SearchRow, SearchRow)
      */
-    void addSearchRows(SearchRow first, SearchRow last);
+    boolean addSearchRows(SearchRow first, SearchRow last);
 
     /**
      * Check if this batch is full.
@@ -47,4 +50,16 @@ public interface IndexLookupBatch {
      * @return List of future cursors for collected search rows.
      */
     List<Future<Cursor>> find();
+
+    /**
+     * Get plan for EXPLAIN.
+     *
+     * @return plan
+     */
+    String getPlanSQL();
+
+    /**
+     * Reset this batch to clear state. This method will be called before each query execution.
+     */
+    void reset();
 }

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

@@ -6,8 +6,6 @@
 package org.h2.index;
 
 import java.util.ArrayList;
-import java.util.List;
-import java.util.concurrent.Future;
 import org.h2.api.ErrorCode;
 import org.h2.engine.Database;
 import org.h2.engine.DbObject;

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

@@ -24,7 +24,7 @@ public class ViewCursor implements Cursor {
     private final SearchRow first, last;
     private Row current;
 
-    ViewCursor(ViewIndex index, LocalResult result, SearchRow first,
+    public ViewCursor(ViewIndex index, LocalResult result, SearchRow first,
             SearchRow last) {
         this.table = index.getTable();
         this.index = index;

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

@@ -21,7 +21,7 @@ import org.h2.result.SearchRow;
 import org.h2.result.SortOrder;
 import org.h2.table.Column;
 import org.h2.table.IndexColumn;
-import org.h2.table.SubQueryInfo;
+import org.h2.table.JoinBatch;
 import org.h2.table.TableFilter;
 import org.h2.table.TableView;
 import org.h2.util.IntArray;
@@ -93,6 +93,15 @@ public class ViewIndex extends BaseIndex implements SpatialIndex {
         }
     }
 
+    @Override
+    public IndexLookupBatch createLookupBatch(TableFilter filter) {
+        if (recursive) {
+            // we do not support batching for recursive queries
+            return null;
+        }
+        return JoinBatch.createViewIndexLookupBatch(this);
+    }
+
     public Session getSession() {
         return createSession;
     }
@@ -199,69 +208,69 @@ public class ViewIndex extends BaseIndex implements SpatialIndex {
             TableFilter[] filters, int filter, SortOrder sortOrder, boolean preliminary) {
         assert filters != null;
         Prepared p;
-        SubQueryInfo upper = session.getSubQueryInfo();
-        SubQueryInfo info = new SubQueryInfo(upper,
-                masks, filters, filter, sortOrder, preliminary);
-        session.setSubQueryInfo(info);
+        session.pushSubQueryInfo(masks, filters, filter, sortOrder);
         try {
             p = session.prepare(sql, true);
         } finally {
-            session.setSubQueryInfo(upper);
+            session.popSubQueryInfo();
         }
         return (Query) p;
     }
 
-    private Cursor find(Session session, SearchRow first, SearchRow last,
+    private Cursor findRecursive(Session session, SearchRow first, SearchRow last,
             SearchRow intersection) {
-        if (recursive) {
-            LocalResult recResult = view.getRecursiveResult();
-            if (recResult != null) {
-                recResult.reset();
-                return new ViewCursor(this, recResult, first, last);
-            }
-            if (query == null) {
-                query = (Query) createSession.prepare(querySQL, true);
-            }
-            if (!(query instanceof SelectUnion)) {
-                throw DbException.get(ErrorCode.SYNTAX_ERROR_2,
-                        "recursive queries without UNION ALL");
-            }
-            SelectUnion union = (SelectUnion) query;
-            if (union.getUnionType() != SelectUnion.UNION_ALL) {
-                throw DbException.get(ErrorCode.SYNTAX_ERROR_2,
-                        "recursive queries without UNION ALL");
+        assert recursive;
+        LocalResult recResult = view.getRecursiveResult();
+        if (recResult != null) {
+            recResult.reset();
+            return new ViewCursor(this, recResult, first, last);
+        }
+        if (query == null) {
+            query = (Query) createSession.prepare(querySQL, true);
+        }
+        if (!query.isUnion()) {
+            throw DbException.get(ErrorCode.SYNTAX_ERROR_2,
+                    "recursive queries without UNION ALL");
+        }
+        SelectUnion union = (SelectUnion) query;
+        if (union.getUnionType() != SelectUnion.UNION_ALL) {
+            throw DbException.get(ErrorCode.SYNTAX_ERROR_2,
+                    "recursive queries without UNION ALL");
+        }
+        Query left = union.getLeft();
+        // to ensure the last result is not closed
+        left.disableCache();
+        LocalResult r = left.query(0);
+        LocalResult result = union.getEmptyResult();
+        // ensure it is not written to disk,
+        // because it is not closed normally
+        result.setMaxMemoryRows(Integer.MAX_VALUE);
+        while (r.next()) {
+            result.addRow(r.currentRow());
+        }
+        Query right = union.getRight();
+        r.reset();
+        view.setRecursiveResult(r);
+        // to ensure the last result is not closed
+        right.disableCache();
+        while (true) {
+            r = right.query(0);
+            if (r.getRowCount() == 0) {
+                break;
             }
-            Query left = union.getLeft();
-            // to ensure the last result is not closed
-            left.disableCache();
-            LocalResult r = left.query(0);
-            LocalResult result = union.getEmptyResult();
-            // ensure it is not written to disk,
-            // because it is not closed normally
-            result.setMaxMemoryRows(Integer.MAX_VALUE);
             while (r.next()) {
                 result.addRow(r.currentRow());
             }
-            Query right = union.getRight();
             r.reset();
             view.setRecursiveResult(r);
-            // to ensure the last result is not closed
-            right.disableCache();
-            while (true) {
-                r = right.query(0);
-                if (r.getRowCount() == 0) {
-                    break;
-                }
-                while (r.next()) {
-                    result.addRow(r.currentRow());
-                }
-                r.reset();
-                view.setRecursiveResult(r);
-            }
-            view.setRecursiveResult(null);
-            result.done();
-            return new ViewCursor(this, result, first, last);
         }
+        view.setRecursiveResult(null);
+        result.done();
+        return new ViewCursor(this, result, first, last);
+    }
+
+    public void setupQueryParameters(Session session, SearchRow first, SearchRow last,
+            SearchRow intersection) {
         ArrayList<Parameter> paramList = query.getParameters();
         if (originalParameters != null) {
             for (int i = 0, size = originalParameters.size(); i < size; i++) {
@@ -298,6 +307,14 @@ public class ViewIndex extends BaseIndex implements SpatialIndex {
                 setParameter(paramList, idx++, intersection.getValue(i));
             }
         }
+    }
+
+    private Cursor find(Session session, SearchRow first, SearchRow last,
+            SearchRow intersection) {
+        if (recursive) {
+            return findRecursive(session, first, last, intersection);
+        }
+        setupQueryParameters(session, first, last, intersection);
         LocalResult result = query.query(0);
         return new ViewCursor(this, result, first, last);
     }
@@ -313,6 +330,10 @@ public class ViewIndex extends BaseIndex implements SpatialIndex {
         param.setValue(v);
     }
 
+    public Query getQuery() {
+        return query;
+    }
+
     private Query getQuery(Session session, int[] masks,
             TableFilter[] filters, int filter, SortOrder sortOrder) {
         Query q = prepareSubQuery(querySQL, session, masks, filters, filter, sortOrder, true);
@@ -454,5 +475,4 @@ public class ViewIndex extends BaseIndex implements SpatialIndex {
     public boolean isRecursive() {
         return recursive;
     }
-
 }

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

+/*
+ * 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
+ */
+package org.h2.table;
+
+import java.util.AbstractList;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.Future;
+import org.h2.command.dml.Query;
+import org.h2.command.dml.Select;
+import org.h2.command.dml.SelectUnion;
+import org.h2.index.Cursor;
+import org.h2.index.IndexCursor;
+import org.h2.index.IndexLookupBatch;
+import org.h2.index.ViewCursor;
+import org.h2.index.ViewIndex;
+import org.h2.message.DbException;
+import org.h2.result.LocalResult;
+import org.h2.result.Row;
+import org.h2.result.SearchRow;
+import org.h2.util.DoneFuture;
+import org.h2.util.LazyFuture;
+import org.h2.util.New;
+import org.h2.value.Value;
+import org.h2.value.ValueLong;
+
+/**
+ * Support for asynchronous batched index lookups on joins.
+ * 
+ * @see org.h2.index.Index#createLookupBatch(TableFilter)
+ * @see IndexLookupBatch
+ * @author Sergi Vladykin
+ */
+public final class JoinBatch {
+    private static final Cursor EMPTY_CURSOR = new Cursor() {
+        @Override
+        public boolean previous() {
+            return false;
+        }
+
+        @Override
+        public boolean next() {
+            return false;
+        }
+
+        @Override
+        public SearchRow getSearchRow() {
+            return null;
+        }
+
+        @Override
+        public Row get() {
+            return null;
+        }
+
+        @Override
+        public String toString() {
+            return "EMPTY_CURSOR";
+        }
+    };
+
+    private static final Future<Cursor> EMPTY_FUTURE_CURSOR = new DoneFuture<Cursor>(EMPTY_CURSOR);
+
+    private boolean batchedSubQuery;
+    private Future<Cursor> viewTopFutureCursor;
+
+    private JoinFilter[] filters;
+    private JoinFilter top;
+
+    private boolean started;
+
+    private JoinRow current;
+    private boolean found;
+
+    /**
+     * This filter joined after this batched join and can be used normally.
+     */
+    private final TableFilter additionalFilter;
+
+    /**
+     * @param filtersCount number of filters participating in this batched join
+     * @param additionalFilter table filter after this batched join.
+     */
+    public JoinBatch(int filtersCount, TableFilter additionalFilter) {
+        if (filtersCount > 32) {
+            // This is because we store state in a 64 bit field, 2 bits per joined table.
+            throw DbException.getUnsupportedException("Too many tables in join (at most 32 supported).");
+        }
+        filters = new JoinFilter[filtersCount];
+        this.additionalFilter = additionalFilter;
+    }
+
+    /**
+     * Get the lookup batch for the given table filter.
+     *
+     * @param joinFilterId joined table filter id
+     * @return lookup batch
+     */
+    public IndexLookupBatch getLookupBatch(int joinFilterId) {
+        return filters[joinFilterId].lookupBatch;
+    }
+    
+    /**
+     * Reset state of this batch.
+     */
+    public void reset() {
+        current = null;
+        started = false;
+        found = false;
+        for (JoinFilter jf : filters) {
+            jf.reset();
+        }
+        if (additionalFilter != null) {
+            additionalFilter.reset();
+        }
+    }
+
+    /**
+     * @param filter table filter
+     * @param lookupBatch lookup batch
+     */
+    public void register(TableFilter filter, IndexLookupBatch lookupBatch) {
+        assert filter != null;
+        top = new JoinFilter(lookupBatch, filter, top);
+        filters[top.id] = top;
+    }
+
+    /**
+     * @param filterId table filter id
+     * @param column column
+     * @return column value for current row
+     */
+    public Value getValue(int filterId, Column column) {
+        Object x = current.row(filterId);
+        assert x != null;
+        Row row = current.isRow(filterId) ? (Row) x : ((Cursor) x).get();
+        int columnId = column.getColumnId();
+        if (columnId == -1) {
+            return ValueLong.get(row.getKey());
+        }
+        Value value = row.getValue(column.getColumnId());
+        if (value == null) {
+            throw DbException.throwInternalError("value is null: " + column + " " + row);
+        }
+        return value;
+    }
+
+    private void start() {
+        // initialize current row
+        current = new JoinRow(new Object[filters.length]);
+        // initialize top cursor
+        Cursor cursor;
+        if (batchedSubQuery) {
+            assert viewTopFutureCursor != null;
+            cursor = get(viewTopFutureCursor);
+        } else {
+            // setup usual index cursor
+            TableFilter f = top.filter;
+            IndexCursor indexCursor = f.getIndexCursor();
+            indexCursor.find(f.getSession(), f.getIndexConditions());
+            cursor = indexCursor;
+        }
+        current.updateRow(top.id, cursor, JoinRow.S_NULL, JoinRow.S_CURSOR);
+        // we need fake first row because batchedNext always will move to the next row
+        JoinRow fake = new JoinRow(null);
+        fake.next = current;
+        current = fake;
+    }
+
+    /**
+     * Get next row from the join batch.
+     * 
+     * @return
+     */
+    public boolean next() {
+        if (!started) {
+            start();
+            started = true;
+        }
+        if (additionalFilter == null) {
+            if (batchedNext()) {
+                assert current.isComplete();
+                return true;
+            }
+            return false;
+        }
+        for (;;) {
+            if (!found) {
+                if (!batchedNext()) {
+                    return false;
+                }
+                assert current.isComplete();
+                found = true;
+                additionalFilter.reset();
+            }
+            // we call furtherFilter in usual way outside of this batch because it is more effective
+            if (additionalFilter.next()) {
+                return true;
+            }
+            found = false;
+        }
+    }
+
+    private static Cursor get(Future<Cursor> f) {
+        Cursor c;
+        try {
+            c = f.get();
+        } catch (Exception e) {
+            throw DbException.convert(e);
+        }
+        return c == null ? EMPTY_CURSOR : c;
+    }
+
+    private boolean batchedNext() {
+        if (current == null) {
+            // after last
+            return false;
+        }
+        // go next
+        current = current.next;
+        if (current == null) {
+            return false;
+        }
+        current.prev = null;
+    
+        final int lastJfId = filters.length - 1;
+        
+        int jfId = lastJfId;
+        while (current.row(jfId) == null) {
+            // lookup for the first non fetched filter for the current row
+            jfId--;
+        }
+        
+        for (;;) {
+            fetchCurrent(jfId);
+            
+            if (!current.isDropped()) {
+                // if current was not dropped then it must be fetched successfully
+                if (jfId == lastJfId) {
+                    // the whole join row is ready to be returned
+                    return true;
+                }
+                JoinFilter join = filters[jfId + 1];
+                if (join.isBatchFull()) {
+                    // get future cursors for join and go right to fetch them
+                    current = join.find(current);
+                }
+                if (current.row(join.id) != null) {
+                    // either find called or outer join with null-row
+                    jfId = join.id;
+                    continue;
+                }
+            }
+            // we have to go down and fetch next cursors for jfId if it is possible
+            if (current.next == null) {
+                // either dropped or null-row
+                if (current.isDropped()) {
+                    current = current.prev;
+                    if (current == null) {
+                        return false;
+                    }
+                }
+                assert !current.isDropped();
+                assert jfId != lastJfId;
+                
+                jfId = 0;
+                while (current.row(jfId) != null) {
+                    jfId++;
+                }
+                // force find on half filled batch (there must be either searchRows 
+                // or Cursor.EMPTY set for null-rows)
+                current = filters[jfId].find(current);
+            } else {
+                // here we don't care if the current was dropped
+                current = current.next;
+                assert !current.isRow(jfId);
+                while (current.row(jfId) == null) {
+                    assert jfId != top.id;
+                    // need to go left and fetch more search rows
+                    jfId--;
+                    assert !current.isRow(jfId);
+                }
+            }
+        }
+    }
+    
+    @SuppressWarnings("unchecked")
+    private void fetchCurrent(final int jfId) {
+        assert current.prev == null || current.prev.isRow(jfId) : "prev must be already fetched";
+        assert jfId == 0 || current.isRow(jfId - 1) : "left must be already fetched";
+
+        assert !current.isRow(jfId) : "double fetching";
+
+        Object x = current.row(jfId);
+        assert x != null : "x null";
+
+        // in case of outer join we don't have any future around empty cursor
+        boolean newCursor = x == EMPTY_CURSOR;
+
+        if (newCursor) {
+            if (jfId == 0) {
+                // the top cursor is new and empty, then the whole select will not produce any rows
+                current.drop();
+                return;
+            }
+        } else if (current.isFuture(jfId)) {
+            // get cursor from a future
+            x = get((Future<Cursor>) x);
+            current.updateRow(jfId, x, JoinRow.S_FUTURE, JoinRow.S_CURSOR);
+            newCursor = true;
+        }
+
+        final JoinFilter jf = filters[jfId];
+        Cursor c = (Cursor) x;
+        assert c != null;
+        JoinFilter join = jf.join;
+
+        for (;;) {
+            if (c == null || !c.next()) {
+                if (newCursor && jf.isOuterJoin()) {
+                    // replace cursor with null-row
+                    current.updateRow(jfId, jf.getNullRow(), JoinRow.S_CURSOR, JoinRow.S_ROW);
+                    c = null;
+                    newCursor = false;
+                } else {
+                    // cursor is done, drop it
+                    current.drop();
+                    return;
+                }
+            }
+            if (!jf.isOk(c == null)) {
+                // try another row from the cursor
+                continue;
+            }
+            boolean joinEmpty = false;
+            if (join != null && !join.collectSearchRows()) {
+                if (join.isOuterJoin()) {
+                    joinEmpty = true;
+                } else {
+                    // join will fail, try next row in the cursor
+                    continue;
+                }
+            }
+            if (c != null) {
+                current = current.copyBehind(jfId);
+                // update jf, set current row from cursor
+                current.updateRow(jfId, c.get(), JoinRow.S_CURSOR, JoinRow.S_ROW);
+            }
+            if (joinEmpty) {
+                // update jf.join, set an empty cursor
+                current.updateRow(join.id, EMPTY_CURSOR, JoinRow.S_NULL, JoinRow.S_CURSOR);
+            }
+            return;
+        }
+    }
+
+    /**
+     * @return Adapter to allow joining to this batch in sub-queries and views.
+     */
+    private IndexLookupBatch viewIndexLookupBatch(ViewIndex viewIndex) {
+        return new ViewIndexLookupBatch(viewIndex);
+    }
+
+    /**
+     * Create index lookup batch for a view index.
+     * 
+     * @param viewIndex view index
+     * @return index lookup batch or {@code null} if batching is not supported for this query
+     */
+    public static IndexLookupBatch createViewIndexLookupBatch(ViewIndex viewIndex) {
+        Query query = viewIndex.getQuery();
+        if (query.isUnion()) {
+            ViewIndexLookupBatchUnion unionBatch = new ViewIndexLookupBatchUnion(viewIndex);
+            return unionBatch.initialize() ? unionBatch : null;
+        }
+        JoinBatch jb = ((Select) query).getJoinBatch();
+        if (jb == null || jb.getLookupBatch(0) == null) {
+            // our sub-query is not batched or is top batched sub-query
+            return null;
+        }
+        assert !jb.batchedSubQuery;
+        jb.batchedSubQuery = true;
+        return jb.viewIndexLookupBatch(viewIndex);
+    }
+
+    /**
+     * Create fake index lookup batch for non-batched table filter. 
+     *
+     * @param filter the table filter
+     * @return fake index lookup batch
+     */
+    public static IndexLookupBatch createFakeIndexLookupBatch(TableFilter filter) {
+        return new FakeLookupBatch(filter);
+    }
+
+    @Override
+    public String toString() {
+        return "JoinBatch->\nprev->" + (current == null ? null : current.prev) +
+                "\ncurr->" + current + 
+                "\nnext->" + (current == null ? null : current.next);
+    }
+
+    /**
+     * Table filter participating in batched join.
+     */
+    private static final class JoinFilter {
+        private final TableFilter filter;
+        private final JoinFilter join;
+        private final int id;
+
+        private final IndexLookupBatch lookupBatch;
+
+        private JoinFilter(IndexLookupBatch lookupBatch, TableFilter filter, JoinFilter join) {
+            this.filter = filter;
+            this.id = filter.getJoinFilterId();
+            this.join = join;
+            this.lookupBatch = lookupBatch;
+            assert lookupBatch != null || id == 0;
+        }
+
+        private void reset() {
+            if (lookupBatch != null) {
+                lookupBatch.reset();
+            }
+        }
+
+        private Row getNullRow() {
+            return filter.getTable().getNullRow();
+        }
+
+        private boolean isOuterJoin() {
+            return filter.isJoinOuter();
+        }
+
+        private boolean isBatchFull() {
+            return lookupBatch.isBatchFull();
+        }
+
+        private boolean isOk(boolean ignoreJoinCondition) {
+            boolean filterOk = filter.isOk(filter.getFilterCondition());
+            boolean joinOk = filter.isOk(filter.getJoinCondition());
+
+            return filterOk && (ignoreJoinCondition || joinOk);
+        }
+
+        private boolean collectSearchRows() {
+            assert !isBatchFull();
+            IndexCursor c = filter.getIndexCursor();
+            c.prepare(filter.getSession(), filter.getIndexConditions());
+            if (c.isAlwaysFalse()) {
+                return false;
+            }
+            return lookupBatch.addSearchRows(c.getStart(), c.getEnd());
+        }
+
+        private List<Future<Cursor>> find() {
+            return lookupBatch.find();
+        }
+
+        private JoinRow find(JoinRow current) {
+            assert current != null;
+
+            // lookupBatch is allowed to be empty when we have some null-rows and forced find call
+            List<Future<Cursor>> result = lookupBatch.find();
+
+            // go backwards and assign futures
+            for (int i = result.size(); i > 0;) {
+                assert current.isRow(id - 1);
+                if (current.row(id) == EMPTY_CURSOR) {
+                    // outer join support - skip row with existing empty cursor
+                    current = current.prev;
+                    continue;
+                }
+                assert current.row(id) == null;
+                Future<Cursor> future = result.get(--i);
+                if (future == null) {
+                    current.updateRow(id, EMPTY_CURSOR, JoinRow.S_NULL, JoinRow.S_CURSOR);
+                } else {
+                    current.updateRow(id, future, JoinRow.S_NULL, JoinRow.S_FUTURE);
+                }
+                if (current.prev == null || i == 0) {
+                    break;
+                }
+                current = current.prev;
+            }
+
+            // handle empty cursors (because of outer joins) at the beginning
+            while (current.prev != null && current.prev.row(id) == EMPTY_CURSOR) {
+                current = current.prev;
+            }
+            assert current.prev == null || current.prev.isRow(id);
+            assert current.row(id) != null;
+            assert !current.isRow(id);
+
+            // the last updated row
+            return current;
+        }
+
+        @Override
+        public String toString() {
+            return "JoinFilter->" + filter;
+        }
+    }
+
+    /**
+     * Linked row in batched join.
+     */
+    private static final class JoinRow {
+        private static final long S_NULL = 0;
+        private static final long S_FUTURE = 1;
+        private static final long S_CURSOR = 2;
+        private static final long S_ROW = 3;
+
+        private static final long S_MASK = 3;
+
+        /**
+         * May contain one of the following:
+         * <br/>- {@code null}: means that we need to get future cursor for this row
+         * <br/>- {@link Future}: means that we need to get a new {@link Cursor} from the {@link Future}
+         * <br/>- {@link Cursor}: means that we need to fetch {@link Row}s from the {@link Cursor}
+         * <br/>- {@link Row}: the {@link Row} is already fetched and is ready to be used
+         */
+        private Object[] row;
+        private long state;
+
+        private JoinRow prev;
+        private JoinRow next;
+
+        /**
+         * @param row Row.
+         */
+        private JoinRow(Object[] row) {
+            this.row = row;
+        }
+
+        /**
+         * @param joinFilterId Join filter id.
+         * @return Row state.
+         */
+        private long getState(int joinFilterId) {
+            return (state >>> (joinFilterId << 1)) & S_MASK;
+        }
+
+        /**
+         * Allows to do a state transition in the following order:
+         * 0. Slot contains {@code null} ({@link #S_NULL}).
+         * 1. Slot contains {@link Future} ({@link #S_FUTURE}).
+         * 2. Slot contains {@link Cursor} ({@link #S_CURSOR}).
+         * 3. Slot contains {@link Row} ({@link #S_ROW}).
+         *
+         * @param joinFilterId {@link JoinRow} filter id.
+         * @param i Increment by this number of moves.
+         */
+        private void incrementState(int joinFilterId, long i) {
+            assert i > 0 : i;
+            state += i << (joinFilterId << 1);
+        }
+
+        private void updateRow(int joinFilterId, Object x, long oldState, long newState) {
+            assert getState(joinFilterId) == oldState : "old state: " + getState(joinFilterId);
+            row[joinFilterId] = x;
+            incrementState(joinFilterId, newState - oldState);
+            assert getState(joinFilterId) == newState : "new state: " + getState(joinFilterId);
+        }
+
+        private Object row(int joinFilterId) {
+            return row[joinFilterId];
+        }
+
+        private boolean isRow(int joinFilterId) {
+            return getState(joinFilterId) == S_ROW;
+        }
+
+        private boolean isFuture(int joinFilterId) {
+            return getState(joinFilterId) == S_FUTURE;
+        }
+
+        private boolean isCursor(int joinFilterId) {
+            return getState(joinFilterId) == S_CURSOR;
+        }
+
+        private boolean isComplete() {
+            return isRow(row.length - 1);
+        }
+
+        private boolean isDropped() {
+            return row == null;
+        }
+
+        private void drop() {
+            if (prev != null) {
+                prev.next = next;
+            }
+            if (next != null) {
+                next.prev = prev;
+            }
+            row = null;
+        }
+
+        /**
+         * Copy this JoinRow behind itself in linked list of all in progress rows.
+         *
+         * @param jfId The last fetched filter id.
+         * @return The copy.
+         */
+        private JoinRow copyBehind(int jfId) {
+            assert isCursor(jfId);
+            assert jfId + 1 == row.length || row[jfId + 1] == null;
+
+            Object[] r = new Object[row.length];
+            if (jfId != 0) {
+                System.arraycopy(row, 0, r, 0, jfId);
+            }
+            JoinRow copy = new JoinRow(r);
+            copy.state = state;
+
+            if (prev != null) {
+                copy.prev = prev;
+                prev.next = copy;
+            }
+            prev = copy;
+            copy.next = this;
+
+            return copy;
+        }
+
+        @Override
+        public String toString() {
+            return "JoinRow->" + Arrays.toString(row);
+        }
+    }
+
+    /**
+     * Fake Lookup batch for indexes which do not support batching but have to participate 
+     * in batched joins.
+     */
+    private static final class FakeLookupBatch implements IndexLookupBatch {
+        private final TableFilter filter;
+
+        private SearchRow first;
+        private SearchRow last;
+
+        private boolean full;
+
+        private final List<Future<Cursor>> result = new SingletonList<Future<Cursor>>();
+
+        private FakeLookupBatch(TableFilter filter) {
+            this.filter = filter;
+        }
+
+        @Override
+        public String getPlanSQL() {
+            return "fake";
+        }
+
+        @Override
+        public void reset() {
+            full = false;
+            first = last = null;
+            result.set(0, null);
+        }
+
+        @Override
+        public boolean addSearchRows(SearchRow first, SearchRow last) {
+            assert !full;
+            this.first = first;
+            this.last = last;
+            full = true;
+            return true;
+        }
+
+        @Override
+        public boolean isBatchFull() {
+            return full;
+        }
+
+        @Override
+        public List<Future<Cursor>> find() {
+            if (!full) {
+                return Collections.emptyList();
+            }
+            Cursor c = filter.getIndex().find(filter, first, last);
+            result.set(0, new DoneFuture<Cursor>(c));
+            full = false;
+            first = last = null;
+            return result;
+        }
+    }
+
+    /**
+     * Simple singleton list.
+     */
+    private static final class SingletonList<E> extends AbstractList<E> {
+        private E element;
+
+        @Override
+        public E get(int index) {
+            assert index == 0;
+            return element;
+        }
+
+        @Override
+        public E set(int index, E element) {
+            assert index == 0;
+            this.element = element;
+            return null;
+        }
+
+        @Override
+        public int size() {
+            return 1;
+        }
+    }
+    
+    /**
+     * Base class for SELECT and SELECT UNION view index lookup batches.
+     */
+    private abstract static class ViewIndexLookupBatchBase<R extends QueryRunnerBase> 
+            implements IndexLookupBatch {
+        protected final ViewIndex viewIndex;
+        private final ArrayList<Future<Cursor>> result = New.arrayList();
+        private int resultSize;
+        private boolean findCalled;
+
+        protected ViewIndexLookupBatchBase(ViewIndex viewIndex) {
+            this.viewIndex = viewIndex;
+        }
+
+        @Override
+        public String getPlanSQL() {
+            return "view";
+        }
+
+        protected abstract boolean collectSearchRows(R r);
+
+        protected abstract R newQueryRunner();
+
+        protected abstract void startQueryRunners(int resultSize);
+
+        protected final boolean resetAfterFind() {
+            if (!findCalled) {
+                return false;
+            }
+            findCalled = false;
+            // method find was called, we need to reset futures to initial state for reuse
+            for (int i = 0; i < resultSize; i++) {
+                queryRunner(i).reset();
+            }
+            resultSize = 0;
+            return true;
+        }
+
+        @SuppressWarnings("unchecked")
+        protected R queryRunner(int i) {
+            return (R) result.get(i);
+        }
+
+        @Override
+        public final boolean addSearchRows(SearchRow first, SearchRow last) {
+            resetAfterFind();
+            viewIndex.setupQueryParameters(viewIndex.getSession(), first, last, null);
+            R r;
+            if (resultSize < result.size()) {
+                // get reused runner
+                r = queryRunner(resultSize);
+            } else {
+                // create new runner
+                result.add(r = newQueryRunner());
+            }
+            r.first = first;
+            r.last = last;
+            if (!collectSearchRows(r)) {
+                r.clear();
+                return false;
+            }
+            resultSize++;
+            return true;
+        }
+        
+        @Override
+        public void reset() {
+            if (resultSize != 0 && !resetAfterFind()) {
+                // find was not called, need to just clear runners
+                for (int i = 0; i < resultSize; i++) {
+                    ((QueryRunnerBase) result.get(i)).clear();
+                }
+                resultSize = 0;
+            }
+        }
+        
+        @Override
+        public final List<Future<Cursor>> find() {
+            if (resultSize == 0) {
+                return Collections.emptyList();
+            }
+            findCalled = true;
+            startQueryRunners(resultSize);
+            return resultSize == result.size() ? result : result.subList(0, resultSize);
+        }
+    }
+    
+    /**
+     * Lazy query runner base.
+     */
+    private abstract static class QueryRunnerBase extends LazyFuture<Cursor> {
+        protected final ViewIndex viewIndex;
+        protected SearchRow first;
+        protected SearchRow last;
+
+        public QueryRunnerBase(ViewIndex viewIndex) {
+            this.viewIndex = viewIndex;
+        }
+
+        protected void clear() {
+            first = last = null;
+        }
+
+        @Override
+        public final boolean reset() {
+            if (super.reset()) {
+                return true;
+            }
+            // this query runner was never executed, need to clear manually
+            clear();
+            return false;
+        }
+        
+        protected final ViewCursor newCursor(LocalResult localResult) {
+            ViewCursor cursor = new ViewCursor(viewIndex, localResult, first, last);
+            clear();
+            return cursor;
+        }
+    }
+    
+    /**
+     * View index lookup batch for a simple SELECT.
+     */
+    private final class ViewIndexLookupBatch extends ViewIndexLookupBatchBase<QueryRunner> {
+        private ViewIndexLookupBatch(ViewIndex viewIndex) {
+            super(viewIndex);
+        }
+        
+        @Override
+        protected QueryRunner newQueryRunner() {
+            return new QueryRunner(viewIndex);
+        }
+        
+        @Override
+        protected boolean collectSearchRows(QueryRunner r) {
+            return top.collectSearchRows();
+        }
+
+        @Override
+        public boolean isBatchFull() {
+            return top.isBatchFull();
+        }
+
+        @Override
+        protected void startQueryRunners(int resultSize) {
+            // we do batched find only for top table filter and then lazily run the ViewIndex query
+            // for each received top future cursor
+            List<Future<Cursor>> topFutureCursors = top.find();
+            if (topFutureCursors.size() != resultSize) {
+                throw DbException.throwInternalError("Unexpected result size: " + topFutureCursors.size() +
+                        ", expected :" + resultSize);
+            }
+            for (int i = 0; i < resultSize; i++) {
+                QueryRunner r = queryRunner(i);
+                r.topFutureCursor = topFutureCursors.get(i);
+            }
+        }
+    }
+
+    /**
+     * Query runner.
+     */
+    private final class QueryRunner extends QueryRunnerBase {
+        private Future<Cursor> topFutureCursor;
+
+        public QueryRunner(ViewIndex viewIndex) {
+            super(viewIndex);
+        }
+
+        protected void clear() {
+            super.clear();
+            topFutureCursor = null;
+        }
+
+        @Override
+        protected Cursor run() throws Exception {
+            if (topFutureCursor == null) {
+                // if the top cursor is empty then the whole query will produce empty result
+                return EMPTY_CURSOR;
+            }
+            viewIndex.setupQueryParameters(viewIndex.getSession(), first, last, null);
+            JoinBatch.this.viewTopFutureCursor = topFutureCursor;
+            LocalResult localResult;
+            try {
+                localResult = viewIndex.getQuery().query(0);
+            } finally {
+                JoinBatch.this.viewTopFutureCursor = null;
+            }
+            return newCursor(localResult);
+        }
+    }
+
+    /**
+     * View index lookup batch for UNION queries.
+     */
+    private static final class ViewIndexLookupBatchUnion
+            extends ViewIndexLookupBatchBase<QueryRunnerUnion> {
+        private ArrayList<JoinFilter> filters;
+        private ArrayList<JoinBatch> joinBatches;
+        private boolean onlyBatchedQueries = true;
+
+        protected ViewIndexLookupBatchUnion(ViewIndex viewIndex) {
+            super(viewIndex);
+        }
+
+        private boolean initialize() {
+            return collectJoinBatches(viewIndex.getQuery()) && joinBatches != null;
+        }
+
+        private boolean collectJoinBatches(Query query) {
+            if (query.isUnion()) {
+                SelectUnion union = (SelectUnion) query;
+                return collectJoinBatches(union.getLeft()) &&
+                        collectJoinBatches(union.getRight());
+            }
+            Select select = (Select) query;
+            JoinBatch jb = select.getJoinBatch();
+            if (jb == null) {
+                onlyBatchedQueries = false;
+            } else {
+                if (jb.getLookupBatch(0) == null) {
+                    // we are top sub-query
+                    return false;
+                }
+                assert !jb.batchedSubQuery;
+                jb.batchedSubQuery = true;
+                if (joinBatches == null) {
+                    joinBatches = New.arrayList();
+                    filters = New.arrayList();
+                }
+                filters.add(jb.filters[0]);
+                joinBatches.add(jb);
+            }
+            return true;
+        }
+
+        @Override
+        public boolean isBatchFull() {
+            // if at least one is full
+            for (int i = 0; i < filters.size(); i++) {
+                if (filters.get(i).isBatchFull()) {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        @Override
+        protected boolean collectSearchRows(QueryRunnerUnion r) {
+            boolean collected = false;
+            for (int i = 0; i < filters.size(); i++) {
+                if (filters.get(i).collectSearchRows()) {
+                    collected = true;
+                } else {
+                    r.topFutureCursors[i] = EMPTY_FUTURE_CURSOR;
+                }
+            }
+            return collected || !onlyBatchedQueries;
+        }
+
+        @Override
+        protected QueryRunnerUnion newQueryRunner() {
+            return new QueryRunnerUnion(this);
+        }
+
+        @Override
+        protected void startQueryRunners(int resultSize) {
+            for (int f = 0; f < filters.size(); f++) {
+                List<Future<Cursor>> topFutureCursors = filters.get(f).find();
+                int r = 0, c = 0;
+                for (; r < resultSize; r++) {
+                    Future<Cursor>[] cs = queryRunner(r).topFutureCursors;
+                    if (cs[f] == null) {
+                        cs[f] = topFutureCursors.get(c++);
+                    }
+                }
+                assert r == resultSize;
+                assert c == topFutureCursors.size();
+            }
+        }
+    }
+
+    /**
+     * Query runner for UNION.
+     */
+    private static class QueryRunnerUnion extends QueryRunnerBase {
+        private ViewIndexLookupBatchUnion batchUnion;
+        private Future<Cursor>[] topFutureCursors;
+
+        @SuppressWarnings("unchecked")
+        public QueryRunnerUnion(ViewIndexLookupBatchUnion batchUnion) {
+            super(batchUnion.viewIndex);
+            this.batchUnion = batchUnion;
+            topFutureCursors = new Future[batchUnion.filters.size()];
+        }
+
+        @Override
+        protected void clear() {
+            super.clear();
+            for (int i = 0; i < topFutureCursors.length; i++) {
+                topFutureCursors[i] = null;
+            }
+        }
+
+        @Override
+        protected Cursor run() throws Exception {
+            viewIndex.setupQueryParameters(viewIndex.getSession(), first, last, null);
+            ArrayList<JoinBatch> joinBatches = batchUnion.joinBatches;
+            for (int i = 0, size = joinBatches.size(); i < size; i++) {
+                assert topFutureCursors[i] != null;
+                joinBatches.get(i).viewTopFutureCursor = topFutureCursors[i];
+            }
+            LocalResult localResult;
+            try {
+                localResult = viewIndex.getQuery().query(0);
+            } finally {
+                for (int i = 0, size = joinBatches.size(); i < size; i++) {
+                    joinBatches.get(i).viewTopFutureCursor = null;
+                }
+            }
+            return newCursor(localResult);
+        }
+    }
+}
+

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

@@ -19,7 +19,6 @@ public class SubQueryInfo {
     private TableFilter[] filters;
     private int filter;
     private SortOrder sortOrder;
-    private boolean preliminary;
     private SubQueryInfo upper;
 
     /**
@@ -28,17 +27,14 @@ public class SubQueryInfo {
      * @param filters table filters
      * @param filter current filter
      * @param sortOrder sort order
-     * @param preliminary if this is a preliminary query optimization 
-     *          without global conditions
      */
     public SubQueryInfo(SubQueryInfo upper, int[] masks, TableFilter[] filters, int filter,
-            SortOrder sortOrder, boolean preliminary) {
+            SortOrder sortOrder) {
         this.upper = upper;
         this.masks = masks;
         this.filters = filters;
         this.filter = filter;
         this.sortOrder = sortOrder;
-        this.preliminary = preliminary;
     }
 
     public SubQueryInfo getUpper() {
@@ -60,8 +56,4 @@ public class SubQueryInfo {
     public SortOrder getSortOrder() {
         return sortOrder;
     }
-
-    public boolean isPreliminary() {
-        return preliminary;
-    }
 }

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

@@ -127,6 +127,10 @@ public abstract class Table extends SchemaObjectBase {
         }
     }
 
+    public boolean isView() {
+        return false;
+    }
+
     /**
      * Lock the table for the given session.
      * This method waits until the lock is granted.

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

@@ -5,12 +5,7 @@
  */
 package org.h2.table;
 
-import java.util.AbstractList;
 import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.List;
-import java.util.concurrent.Future;
 import org.h2.command.Parser;
 import org.h2.command.dml.Select;
 import org.h2.engine.Right;
@@ -21,16 +16,15 @@ import org.h2.expression.Comparison;
 import org.h2.expression.ConditionAndOr;
 import org.h2.expression.Expression;
 import org.h2.expression.ExpressionColumn;
-import org.h2.index.Cursor;
 import org.h2.index.Index;
 import org.h2.index.IndexLookupBatch;
 import org.h2.index.IndexCondition;
 import org.h2.index.IndexCursor;
+import org.h2.index.ViewIndex;
 import org.h2.message.DbException;
 import org.h2.result.Row;
 import org.h2.result.SearchRow;
 import org.h2.result.SortOrder;
-import org.h2.util.DoneFuture;
 import org.h2.util.New;
 import org.h2.util.StatementBuilder;
 import org.h2.util.StringUtils;
@@ -48,33 +42,6 @@ public class TableFilter implements ColumnResolver {
     private static final int BEFORE_FIRST = 0, FOUND = 1, AFTER_LAST = 2,
             NULL_ROW = 3;
 
-    private static final Cursor EMPTY_CURSOR = new Cursor() {
-        @Override
-        public boolean previous() {
-            return false;
-        }
-        
-        @Override
-        public boolean next() {
-            return false;
-        }
-        
-        @Override
-        public SearchRow getSearchRow() {
-            return null;
-        }
-        
-        @Override
-        public Row get() {
-            return null;
-        }
-        
-        @Override
-        public String toString() {
-            return "EMPTY_CURSOR";
-        }
-    }; 
-    
     /**
      * Whether this is a direct or indirect (nested) outer join
      */
@@ -94,8 +61,8 @@ public class TableFilter implements ColumnResolver {
      * Batched join support.
      */
     private JoinBatch joinBatch;
-    private JoinFilter joinFilter;
-    
+    private int joinFilterId = -1;
+
     /**
      * Indicates that this filter is used in the plan.
      */
@@ -168,6 +135,10 @@ public class TableFilter implements ColumnResolver {
         hashCode = session.nextObjectId();
     }
 
+    public IndexCursor getIndexCursor() {
+        return cursor;
+    }
+
     @Override
     public Select getSelect() {
         return select;
@@ -339,44 +310,27 @@ public class TableFilter implements ColumnResolver {
      * Start the query. This will reset the scan counts.
      *
      * @param s the session
-     * @return join batch if query runs over index which supports batched lookups, null otherwise
      */
-    public JoinBatch startQuery(Session s) {
-        joinBatch = null;
-        joinFilter = null;
+    public void startQuery(Session s) {
         this.session = s;
         scanCount = 0;
         if (nestedJoin != null) {
             nestedJoin.startQuery(s);
         }
-        JoinBatch batch = null;
         if (join != null) {
-            batch = join.startQuery(s);
-        }
-        IndexLookupBatch lookupBatch = null;
-        if (batch == null && select != null && select.getTopTableFilter() != this) {
-            lookupBatch = index.createLookupBatch(this);
-            if (lookupBatch != null) {
-                batch = new JoinBatch(join);
-            }
-        }
-        if (batch != null) {
-            if (nestedJoin != null) {
-                throw DbException.getUnsupportedException("nested join with batched index");
-            }
-            if (lookupBatch == null) {
-                lookupBatch = index.createLookupBatch(this);
-            }
-            joinBatch = batch;
-            joinFilter = batch.register(this, lookupBatch);
+            join.startQuery(s);
         }
-        return batch;
     }
 
     /**
      * Reset to the current position.
      */
     public void reset() {
+        if (joinBatch != null && joinFilterId == 0) {
+            // reset join batch only on top table filter
+            joinBatch.reset();
+            return;
+        }
         if (nestedJoin != null) {
             nestedJoin.reset();
         }
@@ -387,6 +341,83 @@ public class TableFilter implements ColumnResolver {
         foundOne = false;
     }
 
+    private boolean isAlwaysTopTableFilter(int filter) {
+        if (filter != 0) {
+            return false;
+        }
+        // check if we are at the top table filters all the way up
+        SubQueryInfo info = session.getSubQueryInfo();
+        for (;;) {
+            if (info == null) {
+                return true;
+            }
+            if (info.getFilter() != 0) {
+                return false;
+            }
+            info = info.getUpper();
+        }
+    }
+
+    /**
+     * Attempt to initialize batched join.
+     *
+     * @param id join filter id (index of this table filter in join list)
+     * @param jb join batch if it is already created
+     * @return join batch if query runs over index which supports batched lookups, {@code null} otherwise
+     */
+    public JoinBatch prepareJoinBatch(JoinBatch jb, TableFilter[] filters, int filter) {
+        joinBatch = null;
+        joinFilterId = -1;
+        if (getTable().isView()) {
+            session.pushSubQueryInfo(masks, filters, filter, select.getSortOrder());
+            try {
+                ((ViewIndex) index).getQuery().prepareJoinBatch();
+            } finally {
+                session.popSubQueryInfo();
+            }
+        }
+        // For globally top table filter we don't need to create lookup batch, because
+        // currently it will not be used (this will be shown in ViewIndex.getPlanSQL()). Probably
+        // later on it will make sense to create it to better support X IN (...) conditions,
+        // but this needs to be implemented separately. If isAlwaysTopTableFilter is false
+        // then we either not a top table filter or top table filter in a sub-query, which
+        // in turn is not top in outer query, thus we need to enable batching here to allow
+        // outer query run batched join against this sub-query.
+        IndexLookupBatch lookupBatch = null;
+        if (jb == null && select != null && !isAlwaysTopTableFilter(filter)) {
+            lookupBatch = index.createLookupBatch(this);
+            if (lookupBatch != null) {
+                jb = new JoinBatch(filter + 1, join);
+            }
+        }
+        if (jb != null) {
+            if (nestedJoin != null) {
+                throw DbException.throwInternalError();
+            }
+            joinBatch = jb;
+            joinFilterId = filter;
+            if (lookupBatch == null && !isAlwaysTopTableFilter(filter)) {
+                // createLookupBatch will be called at most once because jb can be
+                // created only if lookupBatch is already not null from the call above.
+                lookupBatch = index.createLookupBatch(this);
+                if (lookupBatch == null) {
+                    // the index does not support lookup batching, need to fake it because we are not top
+                    lookupBatch = JoinBatch.createFakeIndexLookupBatch(this);
+                }
+            }
+            jb.register(this, lookupBatch);
+        }
+        return jb;
+    }
+
+    public int getJoinFilterId() {
+        return joinFilterId;
+    }
+
+    public JoinBatch getJoinBatch() {
+        return joinBatch;
+    }
+
     /**
      * Check if there are more rows to read.
      *
@@ -394,7 +425,7 @@ public class TableFilter implements ColumnResolver {
      */
     public boolean next() {
         if (joinBatch != null) {
-            // will happen only on topTableFilter since jbatch.next does not call join.next()
+            // will happen only on topTableFilter since joinBatch.next() does not call join.next()
             return joinBatch.next();
         }
         if (state == AFTER_LAST) {
@@ -506,7 +537,7 @@ public class TableFilter implements ColumnResolver {
         // scanCount);
     }
 
-    private boolean isOk(Expression condition) {
+    boolean isOk(Expression condition) {
         if (condition == null) {
             return true;
         }
@@ -753,6 +784,19 @@ public class TableFilter implements ColumnResolver {
         if (index != null) {
             buff.append('\n');
             StatementBuilder planBuff = new StatementBuilder();
+            if (joinBatch != null) {
+                IndexLookupBatch lookupBatch = joinBatch.getLookupBatch(joinFilterId);
+                if (lookupBatch == null) {
+                    if (joinFilterId != 0) {
+                        throw DbException.throwInternalError();
+                    }
+                } else {
+                    planBuff.append("batched:");
+                    String batchPlan = lookupBatch.getPlanSQL();
+                    planBuff.append(batchPlan);
+                    planBuff.append(" ");
+                }
+            }
             planBuff.append(index.getPlanSQL());
             if (indexConditions.size() > 0) {
                 planBuff.append(": ");
@@ -965,7 +1009,7 @@ public class TableFilter implements ColumnResolver {
     @Override
     public Value getValue(Column column) {
         if (joinBatch != null) {
-            return joinBatch.getValue(joinFilter, column);
+            return joinBatch.getValue(joinFilterId, column);
         }
         if (currentSearchRow == null) {
             return null;
@@ -1115,562 +1159,4 @@ public class TableFilter implements ColumnResolver {
          */
         void accept(TableFilter f);
     }
-
-    /**
-     * Support for asynchronous batched index lookups on joins.
-     * 
-     * @see Index#findBatched(TableFilter, java.util.Collection)
-     * @see Index#getPreferedLookupBatchSize()
-     * 
-     * @author Sergi Vladykin
-     */
-    private static final class JoinBatch {
-        int filtersCount;
-        JoinFilter[] filters;
-        JoinFilter top;
-        
-        boolean started;
-        
-        JoinRow current;
-        boolean found;
-        
-        /**
-         * This filter joined after this batched join and can be used normally.
-         */
-        final TableFilter additionalFilter;
-        
-        /**
-         * @param additionalFilter table filter after this batched join.
-         */
-        private JoinBatch(TableFilter additionalFilter) {
-            this.additionalFilter = additionalFilter;
-        }
-        
-        /**
-         * @param filter table filter
-         * @param lookupBatch lookup batch
-         */
-        private JoinFilter register(TableFilter filter, IndexLookupBatch lookupBatch) {
-            assert filter != null;
-            filtersCount++;
-            return top = new JoinFilter(lookupBatch, filter, top);
-        }
-        
-        /**
-         * @param filterId table filter id
-         * @param column column
-         * @return column value for current row
-         */
-        private Value getValue(JoinFilter filter, Column column) {
-            Object x = current.row(filter.id);
-            assert x != null;
-            Row row = current.isRow(filter.id) ? (Row) x : ((Cursor) x).get();
-            int columnId = column.getColumnId();
-            if (columnId == -1) {
-                return ValueLong.get(row.getKey());
-            }
-            Value value = row.getValue(column.getColumnId());
-            if (value == null) {
-                throw DbException.throwInternalError("value is null: " + column + " " + row);
-            }
-            return value;
-        }
-        
-        private void start() {
-            if (filtersCount > 32) {
-                // This is because we store state in a 64 bit field, 2 bits per joined table.
-                throw DbException.getUnsupportedException("Too many tables in join (at most 32 supported).");
-            }
-
-            // fill filters
-            filters = new JoinFilter[filtersCount];
-            JoinFilter jf = top;
-            for (int i = 0; i < filtersCount; i++) {
-                filters[jf.id = i] = jf;
-                jf = jf.join;
-            }
-            // initialize current row
-            current = new JoinRow(new Object[filtersCount]);
-            current.updateRow(top.id, top.filter.cursor, JoinRow.S_NULL, JoinRow.S_CURSOR);
-
-            // initialize top cursor
-            top.filter.cursor.find(top.filter.session, top.filter.indexConditions);
-
-            // we need fake first row because batchedNext always will move to the next row
-            JoinRow fake = new JoinRow(null);
-            fake.next = current;
-            current = fake;
-        }
-
-        private boolean next() {
-            if (!started) {
-                start();
-                started = true;
-            }
-            if (additionalFilter == null) {
-                if (batchedNext()) {
-                    assert current.isComplete();
-                    return true;
-                }
-                return false;
-            }
-            for (;;) {
-                if (!found) {
-                    if (!batchedNext()) {
-                        return false;
-                    }
-                    assert current.isComplete();
-                    found = true;
-                    additionalFilter.reset();
-                }
-                // we call furtherFilter in usual way outside of this batch because it is more effective
-                if (additionalFilter.next()) {
-                    return true;
-                }
-                found = false;
-            }
-        }
-        
-        private static Cursor get(Future<Cursor> f) {
-            try {
-                return f.get();
-            } catch (Exception e) {
-                throw DbException.convert(e);
-            }
-        }
-        
-        private boolean batchedNext() {
-            if (current == null) {
-                // after last
-                return false;
-            }
-            // go next
-            current = current.next;
-            if (current == null) {
-                return false;
-            }
-            current.prev = null;
-        
-            final int lastJfId = filtersCount - 1;
-            
-            int jfId = lastJfId;
-            while (current.row(jfId) == null) {
-                // lookup for the first non fetched filter for the current row
-                jfId--;
-            }
-            
-            for (;;) {
-                fetchCurrent(jfId);
-                
-                if (!current.isDropped()) {
-                    // if current was not dropped then it must be fetched successfully
-                    if (jfId == lastJfId) {
-                        // the whole join row is ready to be returned
-                        return true;
-                    }
-                    JoinFilter join = filters[jfId + 1];
-                    if (join.isBatchFull()) {
-                        // get future cursors for join and go right to fetch them
-                        current = join.find(current);
-                    }
-                    if (current.row(join.id) != null) {
-                        // either find called or outer join with null row
-                        jfId = join.id;
-                        continue;
-                    }
-                }
-                // we have to go down and fetch next cursors for jfId if it is possible
-                if (current.next == null) {
-                    // either dropped or null-row
-                    if (current.isDropped()) {
-                        current = current.prev;
-                        if (current == null) {
-                            return false;
-                        }
-                    }
-                    assert !current.isDropped();
-                    assert jfId != lastJfId;
-                    
-                    jfId = 0;
-                    while (current.row(jfId) != null) {
-                        jfId++;
-                    }
-                    // force find on half filled batch (there must be either searchRows 
-                    // or Cursor.EMPTY set for null-rows)
-                    current = filters[jfId].find(current);
-                } else {
-                    // here we don't care if the current was dropped
-                    current = current.next;
-                    assert !current.isRow(jfId);
-                    while (current.row(jfId) == null) {
-                        assert jfId != top.id;
-                        // need to go left and fetch more search rows
-                        jfId--;
-                        assert !current.isRow(jfId);
-                    }
-                }
-            }
-        }
-        
-        @SuppressWarnings("unchecked")
-        private void fetchCurrent(final int jfId) {
-            assert current.prev == null || current.prev.isRow(jfId) : "prev must be already fetched";
-            assert jfId == 0 || current.isRow(jfId - 1) : "left must be already fetched";
-
-            assert !current.isRow(jfId) : "double fetching";
-
-            Object x = current.row(jfId);
-            assert x != null : "x null";
-
-            final JoinFilter jf = filters[jfId];
-            // in case of outer join we don't have any future around empty cursor
-            boolean newCursor = x == EMPTY_CURSOR;
-
-            if (!newCursor && current.isFuture(jfId)) {
-                // get cursor from a future
-                x = get((Future<Cursor>) x);
-                current.updateRow(jfId, x, JoinRow.S_FUTURE, JoinRow.S_CURSOR);
-                newCursor = true;
-            }
-
-            Cursor c = (Cursor) x;
-            assert c != null;
-            JoinFilter join = jf.join;
-
-            for (;;) {
-                if (c == null || !c.next()) {
-                    if (newCursor && jf.isOuterJoin()) {
-                        // replace cursor with null-row
-                        current.updateRow(jfId, jf.getNullRow(), JoinRow.S_CURSOR, JoinRow.S_ROW);
-                        c = null;
-                        newCursor = false;
-                    } else {
-                        // cursor is done, drop it
-                        current.drop();
-                        return;
-                    }
-                }
-                if (!jf.isOk(c == null)) {
-                    // try another row from the cursor
-                    continue;
-                }
-                boolean joinEmpty = false;
-                if (join != null && !join.collectSearchRows()) {
-                    if (join.isOuterJoin()) {
-                        joinEmpty = true;
-                    } else {
-                        // join will fail, try next row in the cursor
-                        continue;
-                    }
-                }
-                if (c != null) {
-                    current = current.copyBehind(jfId);
-                    // get current row from cursor
-                    current.updateRow(jfId, c.get(), JoinRow.S_CURSOR, JoinRow.S_ROW);
-                }
-                if (joinEmpty) {
-                    current.updateRow(join.id, EMPTY_CURSOR, JoinRow.S_NULL, JoinRow.S_CURSOR);
-                }
-                return;
-            }
-        }
-
-        @Override
-        public String toString() {
-            return "JoinBatch->\nprev->" + (current == null ? null : current.prev) +
-                    "\ncurr->" + current + 
-                    "\nnext->" + (current == null ? null : current.next);
-        }
-    }
-    
-    /**
-     * Table filter participating in batched join.
-     */
-    private static final class JoinFilter {
-        final TableFilter filter;
-        final JoinFilter join;
-        int id;
-        
-        IndexLookupBatch lookupBatch;
-        
-        private JoinFilter(IndexLookupBatch lookupBatch, TableFilter filter, JoinFilter join) {
-            this.filter = filter;
-            this.join = join;
-            this.lookupBatch = lookupBatch != null ? lookupBatch : new FakeLookupBatch(filter);
-        }
-        
-        public Row getNullRow() {
-            return filter.table.getNullRow();
-        }
-
-        private boolean isOuterJoin() {
-            return filter.joinOuter;
-        }
-
-        private boolean isBatchFull() {
-            return lookupBatch.isBatchFull();
-        }
-
-        private boolean isOk(boolean ignoreJoinCondition) {
-            boolean filterOk = filter.isOk(filter.filterCondition);
-            boolean joinOk = filter.isOk(filter.joinCondition);
-
-            return filterOk && (ignoreJoinCondition || joinOk);
-        }
-        
-        private boolean collectSearchRows() {
-            assert !isBatchFull();
-            IndexCursor c = filter.cursor;
-            c.prepare(filter.session, filter.indexConditions);
-            if (c.isAlwaysFalse()) {
-                return false;
-            }
-            lookupBatch.addSearchRows(c.getStart(), c.getEnd());
-            return true;
-        }
-        
-        private JoinRow find(JoinRow current) {
-            assert current != null;
-
-            // lookupBatch is allowed to be empty when we have some null-rows and forced find call
-            List<Future<Cursor>> result = lookupBatch.find();
-
-            // go backwards and assign futures
-            for (int i = result.size(); i > 0;) {
-                assert current.isRow(id - 1);
-                if (current.row(id) == EMPTY_CURSOR) {
-                    // outer join support - skip row with existing empty cursor
-                    current = current.prev;
-                    continue;
-                }
-                assert current.row(id) == null;
-                Future<Cursor> future = result.get(--i);
-                if (future == null) {
-                    current.updateRow(id, EMPTY_CURSOR, JoinRow.S_NULL, JoinRow.S_CURSOR);
-                } else {
-                    current.updateRow(id, future, JoinRow.S_NULL, JoinRow.S_FUTURE);
-                }
-                if (current.prev == null || i == 0) {
-                    break;
-                }
-                current = current.prev;
-            }
-
-            // handle empty cursors (because of outer joins) at the beginning
-            while (current.prev != null && current.prev.row(id) == EMPTY_CURSOR) {
-                current = current.prev;
-            }
-            assert current.prev == null || current.prev.isRow(id);
-            assert current.row(id) != null;
-            assert !current.isRow(id);
-
-            // the last updated row
-            return current;
-        }
-        
-        @Override
-        public String toString() {
-            return "JoinFilter->" + filter;
-        }
-    }
-    
-    /**
-     * Linked row in batched join.
-     */
-    private static final class JoinRow {
-        private static final long S_NULL = 0;
-        private static final long S_FUTURE = 1;
-        private static final long S_CURSOR = 2;
-        private static final long S_ROW = 3;
-
-        private static final long S_MASK = 3;
-
-        /**
-         * May contain one of the following:
-         * <br/>- {@code null}: means that we need to get future cursor for this row
-         * <br/>- {@link Future}: means that we need to get a new {@link Cursor} from the {@link Future}
-         * <br/>- {@link Cursor}: means that we need to fetch {@link Row}s from the {@link Cursor}
-         * <br/>- {@link Row}: the {@link Row} is already fetched and is ready to be used
-         */
-        Object[] row;
-        long state;
-
-        JoinRow prev;
-        JoinRow next;
-
-        /**
-         * @param row Row.
-         */
-        private JoinRow(Object[] row) {
-            this.row = row;
-        }
-
-        /**
-         * @param joinFilterId Join filter id.
-         * @return Row state.
-         */
-        private long getState(int joinFilterId) {
-            return (state >>> (joinFilterId << 1)) & S_MASK;
-        }
-
-        /**
-         * Allows to do a state transition in the following order:
-         * 0. Slot contains {@code null} ({@link #S_NULL}).
-         * 1. Slot contains {@link Future} ({@link #S_FUTURE}).
-         * 2. Slot contains {@link Cursor} ({@link #S_CURSOR}).
-         * 3. Slot contains {@link Row} ({@link #S_ROW}).
-         *
-         * @param joinFilterId {@link JoinRow} filter id.
-         * @param i Increment by this number of moves.
-         */
-        private void incrementState(int joinFilterId, long i) {
-            assert i > 0 : i;
-            state += i << (joinFilterId << 1);
-        }
-
-        private void updateRow(int joinFilterId, Object x, long oldState, long newState) {
-            assert getState(joinFilterId) == oldState : "old state: " + getState(joinFilterId);
-            row[joinFilterId] = x;
-            incrementState(joinFilterId, newState - oldState);
-            assert getState(joinFilterId) == newState : "new state: " + getState(joinFilterId);
-        }
-
-        private Object row(int joinFilterId) {
-            return row[joinFilterId];
-        }
-
-        private boolean isRow(int joinFilterId) {
-            return getState(joinFilterId) == S_ROW;
-        }
-
-        private boolean isFuture(int joinFilterId) {
-            return getState(joinFilterId) == S_FUTURE;
-        }
-
-        private boolean isCursor(int joinFilterId) {
-            return getState(joinFilterId) == S_CURSOR;
-        }
-
-        private boolean isComplete() {
-            return isRow(row.length - 1);
-        }
-
-        private boolean isDropped() {
-            return row == null;
-        }
-
-        private void drop() {
-            if (prev != null) {
-                prev.next = next;
-            }
-            if (next != null) {
-                next.prev = prev;
-            }
-            row = null;
-        }
-        
-        /**
-         * Copy this JoinRow behind itself in linked list of all in progress rows.
-         *
-         * @param jfId The last fetched filter id.
-         * @return The copy.
-         */
-        private JoinRow copyBehind(int jfId) {
-            assert isCursor(jfId);
-            assert jfId + 1 == row.length || row[jfId + 1] == null;
-            
-            Object[] r = new Object[row.length];
-            if (jfId != 0) {
-                System.arraycopy(row, 0, r, 0, jfId);
-            }
-            JoinRow copy = new JoinRow(r);
-            copy.state = state;
-            
-            if (prev != null) {
-                copy.prev = prev;
-                prev.next = copy;
-            }
-            prev = copy;
-            copy.next = this;
-            
-            return copy;
-        }
-        
-        @Override
-        public String toString() {
-            return "JoinRow->" + Arrays.toString(row);
-        }
-    }
-
-    /**
-     * Fake Lookup batch for indexes which do not support batching but have to participate 
-     * in batched joins.
-     */
-    private static class FakeLookupBatch implements IndexLookupBatch {
-        final TableFilter filter;
-
-        SearchRow first;
-        SearchRow last;
-
-        boolean full;
-
-        final List<Future<Cursor>> result = new SingletonList<Future<Cursor>>();
-
-        /**
-         * @param index Index.
-         */
-        public FakeLookupBatch(TableFilter filter) {
-            this.filter = filter;
-        }
-
-        @Override
-        public void addSearchRows(SearchRow first, SearchRow last) {
-            assert !full;
-            this.first = first;
-            this.last = last;
-            full = true;
-        }
-
-        @Override
-        public boolean isBatchFull() {
-            return full;
-        }
-
-        @Override
-        public List<Future<Cursor>> find() {
-            if (!full) {
-                return Collections.emptyList();
-            }
-            Cursor c = filter.getIndex().find(filter, first, last);
-            result.set(0, new DoneFuture<Cursor>(c));
-            full = false;
-            first = last = null;
-            return result;
-        }
-    }
-
-    /**
-     * Simple singleton list.
-     */
-    private static class SingletonList<E> extends AbstractList<E> {
-        private E element;
-
-        @Override
-        public E get(int index) {
-            assert index == 0;
-            return element;
-        }
-
-        @Override
-        public E set(int index, E element) {
-            assert index == 0;
-            this.element = element;
-            return null;
-        }
-
-        @Override
-        public int size() {
-            return 1;
-        }
-    }
 }

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

@@ -218,6 +218,11 @@ public class TableView extends Table {
         }
     }
 
+    @Override
+    public boolean isView() {
+        return true;
+    }
+
     /**
      * Check if this view is currently invalid.
      *

h2/src/main/org/h2/util/LazyFuture.java

+/*
+ * 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
+ */
+package org.h2.util;
+
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import org.h2.message.DbException;
+
+/**
+ * Single threaded lazy future. 
+ * 
+ * @param <T>
+ * @author Sergi Vladykin
+ */
+public abstract class LazyFuture<T> implements Future<T> {
+
+    private static final int S_READY = 0;
+    private static final int S_DONE = 1;
+    private static final int S_ERROR = 2;
+    private static final int S_CANCELED = 3;
+    
+    private int state = S_READY;
+    private T result;
+    private Exception error;
+
+    /**
+     * Reset this future to the initial state.
+     * 
+     * @return {@code false} if it was already in initial state 
+     */
+    public boolean reset() {
+        if (state == S_READY) {
+            return false;
+        }
+        state = S_READY;
+        result = null;
+        error = null;
+        return true;
+    }
+
+    /**
+     * Run computation and produce the result.
+     * 
+     * @return the result of computation
+     */
+    protected abstract T run() throws Exception;
+    
+    @Override
+    public boolean cancel(boolean mayInterruptIfRunning) {
+        if (state != S_READY) {
+            return false;
+        }
+        state = S_CANCELED;
+        return true;
+    }
+
+    @Override
+    public T get() throws InterruptedException, ExecutionException {
+        switch (state) {
+        case S_READY:
+            try {
+                result = run();
+                state = S_DONE;
+            } catch (Exception e) {
+                error = e;
+                if (e instanceof InterruptedException) {
+                    throw (InterruptedException) e;
+                }
+                throw new ExecutionException(e);
+            } finally {
+                if (state != S_DONE) {
+                    state = S_ERROR;
+                }
+            }
+            return result;
+        case S_DONE:
+            return result;
+        case S_ERROR:
+            throw new ExecutionException(error);
+        case S_CANCELED:
+            throw new CancellationException();
+        default:
+            throw DbException.throwInternalError();
+        }
+    }
+
+    @Override
+    public T get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException {
+        return get();
+    }
+
+    @Override
+    public boolean isCancelled() {
+        return state == S_CANCELED;
+    }
+
+    @Override
+    public boolean isDone() {
+        return state != S_READY;
+    }
+}

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

@@ -24,6 +24,7 @@ import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.atomic.AtomicInteger;
 import org.h2.api.TableEngine;
 import org.h2.command.ddl.CreateTableData;
 import org.h2.command.dml.OptimizerHints;
@@ -36,6 +37,7 @@ import org.h2.index.Index;
 import org.h2.index.IndexLookupBatch;
 import org.h2.index.IndexType;
 import org.h2.index.SingleRowCursor;
+import org.h2.jdbc.JdbcConnection;
 import org.h2.message.DbException;
 import org.h2.result.Row;
 import org.h2.result.SearchRow;
@@ -383,10 +385,24 @@ public class TestTableEngines extends TestBase {
         deleteDb("testSubQueryInfo");
     }
 
+    private void setBatchingEnabled(Statement stat, boolean enabled) throws SQLException {
+        stat.execute("SET BATCH_JOINS " + enabled);
+        if (!config.networked) {
+            Session s = (Session) ((JdbcConnection) stat.getConnection()).getSession();
+            assertEquals(enabled, s.isJoinBatchEnabled());
+        }
+    }
+    
     private void testBatchedJoin() throws SQLException {
-        deleteDb("tableEngine");
-        Connection conn = getConnection("tableEngine;OPTIMIZE_REUSE_RESULTS=0");
+        deleteDb("testBatchedJoin");
+        Connection conn = getConnection("testBatchedJoin;OPTIMIZE_REUSE_RESULTS=0;BATCH_JOINS=1");
         Statement stat = conn.createStatement();
+        if (!config.networked) {
+            Session s = (Session) ((JdbcConnection) conn).getSession();
+            assertTrue(s.isJoinBatchEnabled());
+        }
+        setBatchingEnabled(stat, false);
+        setBatchingEnabled(stat, true);
         
         TreeSetIndex.exec = Executors.newFixedThreadPool(8, new ThreadFactory() {
             @Override
@@ -399,6 +415,9 @@ public class TestTableEngines extends TestBase {
         
         enableJoinReordering(false);
         try {
+            doTestBatchedJoinSubQueryUnion(stat);
+            
+            TreeSetIndex.lookupBatches.set(0);
             doTestBatchedJoin(stat, 1, 0, 0);
             doTestBatchedJoin(stat, 0, 1, 0);
             doTestBatchedJoin(stat, 0, 0, 1);
@@ -429,11 +448,13 @@ public class TestTableEngines extends TestBase {
             doTestBatchedJoin(stat, 0, 0, 5);
             doTestBatchedJoin(stat, 0, 8, 1);
             doTestBatchedJoin(stat, 0, 2, 1);
+            
+            assertTrue(TreeSetIndex.lookupBatches.get() > 0);
         } finally {
             enableJoinReordering(true);
             TreeSetIndex.exec.shutdownNow();
         }
-        deleteDb("tableEngine");
+        deleteDb("testBatchedJoin");
     }
     
     /**
@@ -447,6 +468,139 @@ public class TestTableEngines extends TestBase {
         }
         OptimizerHints.set(hints);
     }
+
+    private void checkPlan(Statement stat, String sql) throws SQLException {
+        ResultSet rs = stat.executeQuery("EXPLAIN " + sql);
+        assertTrue(rs.next());
+        String plan = rs.getString(1);
+        assertEquals(normalize(sql), normalize(plan));
+    }
+
+    private static String normalize(String sql) {
+        sql = sql.replace('\n', ' ');
+        return sql.replaceAll("\\s+", " ").trim();
+    }
+
+    private void doTestBatchedJoinSubQueryUnion(Statement stat) throws SQLException {
+        String engine = '"' + TreeSetIndexTableEngine.class.getName() + '"';
+        stat.execute("CREATE TABLE t (a int, b int) ENGINE " + engine);
+        TreeSetTable t = TreeSetIndexTableEngine.created;
+        stat.execute("CREATE INDEX T_IDX_A ON t(a)");
+        stat.execute("CREATE INDEX T_IDX_B ON t(b)");
+        setBatchSize(t, 3);
+        for (int i = 0; i < 20; i++) {
+            stat.execute("insert into t values (" + i + "," + (i + 10) + ")");
+        }
+        stat.execute("CREATE TABLE u (a int, b int) ENGINE " + engine);
+        TreeSetTable u = TreeSetIndexTableEngine.created;
+        stat.execute("CREATE INDEX U_IDX_A ON u(a)");
+        stat.execute("CREATE INDEX U_IDX_B ON u(b)");
+        setBatchSize(u, 0);
+        for (int i = 10; i < 25; i++) {
+            stat.execute("insert into u values (" + i + "," + (i - 15)+ ")");
+        }
+
+        checkPlan(stat, "SELECT 1 FROM PUBLIC.T T1 /* PUBLIC.\"scan\" */ "
+                + "INNER JOIN PUBLIC.T T2 /* batched:test PUBLIC.T_IDX_B: B = T1.A */ "
+                + "ON 1=1 WHERE T1.A = T2.B");
+        checkPlan(stat, "SELECT 1 FROM PUBLIC.T T1 /* PUBLIC.\"scan\" */ "
+                + "INNER JOIN PUBLIC.T T2 /* batched:test PUBLIC.T_IDX_B: B = T1.A */ "
+                + "ON 1=1 /* WHERE T1.A = T2.B */ "
+                + "INNER JOIN PUBLIC.T T3 /* batched:test PUBLIC.T_IDX_B: B = T2.A */ "
+                + "ON 1=1 WHERE (T2.A = T3.B) AND (T1.A = T2.B)");
+        checkPlan(stat, "SELECT 1 FROM PUBLIC.T T1 /* PUBLIC.\"scan\" */ "
+                + "INNER JOIN PUBLIC.U /* batched:fake PUBLIC.U_IDX_A: A = T1.A */ "
+                + "ON 1=1 /* WHERE T1.A = U.A */ "
+                + "INNER JOIN PUBLIC.T T2 /* batched:test PUBLIC.T_IDX_B: B = U.B */ "
+                + "ON 1=1 WHERE (T1.A = U.A) AND (U.B = T2.B)");
+        checkPlan(stat, "SELECT 1 FROM ( SELECT A FROM PUBLIC.T ) Z "
+                + "/* SELECT A FROM PUBLIC.T /++ PUBLIC.\"scan\" ++/ */ "
+                + "INNER JOIN PUBLIC.T /* batched:test PUBLIC.T_IDX_B: B = Z.A */ "
+                + "ON 1=1 WHERE Z.A = T.B");
+        checkPlan(stat, "SELECT 1 FROM PUBLIC.T /* PUBLIC.\"scan\" */ "
+                + "INNER JOIN ( SELECT A FROM PUBLIC.T ) Z "
+                + "/* batched:view SELECT A FROM PUBLIC.T /++ batched:test PUBLIC.T_IDX_A: A IS ?1 ++/ "
+                + "WHERE A IS ?1: A = T.B */ ON 1=1 WHERE Z.A = T.B");
+        checkPlan(stat, "SELECT 1 FROM PUBLIC.T /* PUBLIC.\"scan\" */ "
+                + "INNER JOIN ( ((SELECT A FROM PUBLIC.T) UNION ALL (SELECT B FROM PUBLIC.U)) "
+                + "UNION ALL (SELECT B FROM PUBLIC.T) ) Z /* batched:view "
+                + "((SELECT A FROM PUBLIC.T /++ batched:test PUBLIC.T_IDX_A: A IS ?1 ++/ WHERE A IS ?1) "
+                + "UNION ALL "
+                + "(SELECT B FROM PUBLIC.U /++ PUBLIC.U_IDX_B: B IS ?1 ++/ WHERE B IS ?1)) "
+                + "UNION ALL "
+                + "(SELECT B FROM PUBLIC.T /++ batched:test PUBLIC.T_IDX_B: B IS ?1 ++/ WHERE B IS ?1)"
+                + ": A = T.A */ ON 1=1 WHERE Z.A = T.A");
+        checkPlan(stat, "SELECT 1 FROM PUBLIC.T /* PUBLIC.\"scan\" */ "
+                + "INNER JOIN ( SELECT U.A FROM PUBLIC.U INNER JOIN PUBLIC.T ON 1=1 WHERE U.B = T.B ) Z "
+                + "/* batched:view SELECT U.A FROM PUBLIC.U /++ batched:fake PUBLIC.U_IDX_A: A IS ?1 ++/ "
+                + "/++ WHERE U.A IS ?1 ++/ INNER JOIN PUBLIC.T /++ batched:test PUBLIC.T_IDX_B: B = U.B ++/ "
+                + "ON 1=1 WHERE (U.A IS ?1) AND (U.B = T.B): A = T.A */ ON 1=1 WHERE Z.A = T.A");
+        checkPlan(stat, "SELECT 1 FROM PUBLIC.T /* PUBLIC.\"scan\" */ "
+                + "INNER JOIN ( SELECT A FROM PUBLIC.U ) Z /* SELECT A FROM PUBLIC.U "
+                + "/++ PUBLIC.U_IDX_A: A IS ?1 ++/ WHERE A IS ?1: A = T.A */ ON 1=1 WHERE T.A = Z.A");
+        checkPlan(stat, "SELECT 1 FROM "
+                + "( SELECT U.A FROM PUBLIC.U INNER JOIN PUBLIC.T ON 1=1 WHERE U.B = T.B ) Z "
+                + "/* SELECT U.A FROM PUBLIC.U /++ PUBLIC.\"scan\" ++/ "
+                + "INNER JOIN PUBLIC.T /++ batched:test PUBLIC.T_IDX_B: B = U.B ++/ "
+                + "ON 1=1 WHERE U.B = T.B */ "
+                + "INNER JOIN PUBLIC.T /* batched:test PUBLIC.T_IDX_A: A = Z.A */ ON 1=1 WHERE T.A = Z.A");
+        checkPlan(stat, "SELECT 1 FROM "
+                + "( SELECT U.A FROM PUBLIC.T INNER JOIN PUBLIC.U ON 1=1 WHERE T.B = U.B ) Z "
+                + "/* SELECT U.A FROM PUBLIC.T /++ PUBLIC.\"scan\" ++/ "
+                + "INNER JOIN PUBLIC.U /++ PUBLIC.U_IDX_B: B = T.B ++/ "
+                + "ON 1=1 WHERE T.B = U.B */ INNER JOIN PUBLIC.T /* batched:test PUBLIC.T_IDX_A: A = Z.A */ "
+                + "ON 1=1 WHERE Z.A = T.A");
+        checkPlan(stat, "SELECT 1 FROM ( (SELECT A FROM PUBLIC.T) UNION (SELECT A FROM PUBLIC.U) ) Z "
+                + "/* (SELECT A FROM PUBLIC.T /++ PUBLIC.\"scan\" ++/) "
+                + "UNION "
+                + "(SELECT A FROM PUBLIC.U /++ PUBLIC.\"scan\" ++/) */ "
+                + "INNER JOIN PUBLIC.T /* batched:test PUBLIC.T_IDX_A: A = Z.A */ ON 1=1 WHERE Z.A = T.A");
+        checkPlan(stat, "SELECT 1 FROM PUBLIC.U /* PUBLIC.\"scan\" */ "
+                + "INNER JOIN ( (SELECT A, B FROM PUBLIC.T) UNION (SELECT B, A FROM PUBLIC.U) ) Z "
+                + "/* batched:view (SELECT A, B FROM PUBLIC.T /++ batched:test PUBLIC.T_IDX_B: B IS ?1 ++/ "
+                + "WHERE B IS ?1) UNION (SELECT B, A FROM PUBLIC.U /++ PUBLIC.U_IDX_A: A IS ?1 ++/ "
+                + "WHERE A IS ?1): B = U.B */ ON 1=1 /* WHERE U.B = Z.B */ "
+                + "INNER JOIN PUBLIC.T /* batched:test PUBLIC.T_IDX_A: A = Z.A */ ON 1=1 "
+                + "WHERE (U.B = Z.B) AND (Z.A = T.A)"); 
+        checkPlan(stat, "SELECT 1 FROM PUBLIC.U /* PUBLIC.\"scan\" */ "
+                + "INNER JOIN ( SELECT A, B FROM PUBLIC.U ) Z "
+                + "/* batched:fake SELECT A, B FROM PUBLIC.U /++ PUBLIC.U_IDX_A: A IS ?1 ++/ "
+                + "WHERE A IS ?1: A = U.A */ ON 1=1 /* WHERE U.A = Z.A */ "
+                + "INNER JOIN PUBLIC.T /* batched:test PUBLIC.T_IDX_B: B = Z.B */ "
+                + "ON 1=1 WHERE (U.A = Z.A) AND (Z.B = T.B)");
+        
+        // t: a = [ 0..20), b = [10..30)
+        // u: a = [10..25), b = [-5..10)
+        checkBatchedQueryResult(stat, 10, 
+                "select t.a from t, (select t.b from u, t where u.a = t.a) z where t.b = z.b");
+        checkBatchedQueryResult(stat, 5,
+                "select t.a from (select t1.b from t t1, t t2 where t1.a = t2.b) z, t where t.b = z.b + 5");
+        checkBatchedQueryResult(stat, 1,
+                "select t.a from (select u.b from u, t t2 where u.a = t2.b) z, t where t.b = z.b + 1");
+        checkBatchedQueryResult(stat, 15,
+                "select t.a from (select u.b from u, t t2 where u.a = t2.b) z left join t on t.b = z.b");
+        checkBatchedQueryResult(stat, 15,
+                "select t.a from (select t1.b from t t1 left join t t2 on t1.a = t2.b) z, t "
+                + "where t.b = z.b + 5");
+        checkBatchedQueryResult(stat, 1, "select t.a from t,(select 5 as b from t union select 10 from u) z "
+                + "where t.b = z.b");
+        checkBatchedQueryResult(stat, 15, "select t.a from u,(select 5 as b, a from t "
+                + "union select 10, a from u) z, t where t.b = z.b and z.a = u.a");
+
+        stat.execute("DROP TABLE T");
+        stat.execute("DROP TABLE U");
+    }
+
+    private void checkBatchedQueryResult(Statement stat, int size, String sql) throws SQLException {
+        setBatchingEnabled(stat, false);
+        List<List<Object>> expected = query(stat, sql);
+        assertEquals(size, expected.size());
+        setBatchingEnabled(stat, true);
+        List<List<Object>> actual = query(stat, sql);
+        if (!expected.equals(actual)) {
+            fail("\nexpected: " + expected + "\nactual:   " + actual);
+        }
+    }
     
     private void doTestBatchedJoin(Statement stat, int... batchSizes) throws SQLException {
         ArrayList<TreeSetTable> tables = New.arrayList(batchSizes.length);
@@ -501,6 +655,9 @@ public class TestTableEngines extends TestBase {
                 fail();
             }
         }
+        for (int i = 0; i < batchSizes.length; i++) {
+            stat.executeUpdate("DROP TABLE IF EXISTS T" + i);
+        }
     }
 
     private static void assert0(boolean condition, String message) {
@@ -512,7 +669,15 @@ public class TestTableEngines extends TestBase {
     private static void setBatchSize(ArrayList<TreeSetTable> tables, int... batchSizes) {
         for (int i = 0; i < batchSizes.length; i++) {
             int batchSize = batchSizes[i];
-            for (Index idx : tables.get(i).getIndexes()) {
+            setBatchSize(tables.get(i), batchSize);
+        }
+    }
+
+    private static void setBatchSize(TreeSetTable t, int batchSize) {
+        if (t.getIndexes() == null) {
+            t.scan.preferedBatchSize = batchSize;
+        } else {
+            for (Index idx : t.getIndexes()) {
                 ((TreeSetIndex) idx).preferedBatchSize = batchSize;
             }
         }
@@ -1115,6 +1280,8 @@ public class TestTableEngines extends TestBase {
      * An index that internally uses a tree set.
      */
     private static class TreeSetIndex extends BaseIndex implements Comparator<SearchRow> {
+        private static AtomicInteger lookupBatches = new AtomicInteger();
+        
         /**
          * Executor service to test batched joins.
          */
@@ -1145,9 +1312,18 @@ public class TestTableEngines extends TestBase {
         public IndexLookupBatch createLookupBatch(final TableFilter filter) {
             assert filter.getMasks() != null || "scan".equals(getName());
             final int preferedSize = preferedBatchSize; 
-            return preferedSize == 0 ? null : new IndexLookupBatch() {
+            if (preferedSize == 0) {
+                return null;
+            }
+            lookupBatches.incrementAndGet();
+            return new IndexLookupBatch() {
                 List<SearchRow> searchRows = New.arrayList();
 
+                @Override
+                public String getPlanSQL() {
+                    return "test";
+                }
+                
                 @Override public boolean isBatchFull() {
                     return searchRows.size() >= preferedSize * 2;
                 }
@@ -1160,10 +1336,16 @@ public class TestTableEngines extends TestBase {
                 }
 
                 @Override
-                public void addSearchRows(SearchRow first, SearchRow last) {
+                public boolean addSearchRows(SearchRow first, SearchRow last) {
                     assert !isBatchFull();
                     searchRows.add(first);
                     searchRows.add(last);
+                    return true;
+                }
+
+                @Override
+                public void reset() {
+                    searchRows.clear();
                 }
             };
         }