Merge pull request #1456 from katzyn/window

Add experimental implementation of remaining types of window frames

h2/src/docsrc/help/help.csv

@@ -2550,11 +2550,8 @@ They also may require a lot of memory for large queries.
 "
 
 "Other Grammar","Window frame","
-[RANGE BETWEEN {
-    UNBOUNDED PRECEDING AND CURRENT ROW
-    |CURRENT ROW AND UNBOUNDED FOLLOWING
-    |UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
-    }]
+ROWS|RANGE|GROUP
+{windowFramePreceding|BETWEEN windowFrameBound AND windowFrameBound}
 [EXCLUDE {CURRENT ROW|GROUP|TIES|NO OTHERS}]
 ","
 A window frame clause.
@@ -2563,6 +2560,30 @@ Is currently supported only in aggregates and FIRST_VALUE(), LAST_VALUE(), and N
 RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW EXCLUDE GROUP
 "
 
+"Other Grammar","Window frame preceding","
+UNBOUNDED PRECEDING|value PRECEDING|CURRENT ROW
+","
+A window frame preceding clause.
+If value is specified it should be non-negative value or parameter.
+","
+UNBOUNDED PRECEDING
+1 PRECEDING
+CURRENT ROW
+"
+
+"Other Grammar","Window frame bound","
+UNBOUNDED PRECEDING|value PRECEDING|CURRENT ROW
+    |value FOLLOWING|UNBOUNDED FOLLOWING
+","
+A window frame bound clause.
+If value is specified it should be non-negative value or parameter.
+","
+UNBOUNDED PRECEDING
+UNBOUNDED FOLLOWING
+1 FOLLOWING
+CURRENT ROW
+"
+
 "Other Grammar","Term","
 value
     | columnName

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

@@ -176,8 +176,10 @@ import org.h2.expression.aggregate.Aggregate.AggregateType;
 import org.h2.expression.aggregate.JavaAggregate;
 import org.h2.expression.aggregate.Window;
 import org.h2.expression.aggregate.WindowFrame;
-import org.h2.expression.aggregate.WindowFrame.SimpleExtent;
-import org.h2.expression.aggregate.WindowFrame.WindowFrameExclusion;
+import org.h2.expression.aggregate.WindowFrameBound;
+import org.h2.expression.aggregate.WindowFrameBoundType;
+import org.h2.expression.aggregate.WindowFrameExclusion;
+import org.h2.expression.aggregate.WindowFrameUnits;
 import org.h2.expression.aggregate.WindowFunction;
 import org.h2.expression.aggregate.WindowFunction.WindowFunctionType;
 import org.h2.index.Index;
@@ -3074,8 +3076,7 @@ public class Parser {
                     frame = readWindowFrame();
                     break;
                 default:
-                    frame = new WindowFrame(SimpleExtent.RANGE_BETWEEN_UNBOUNDED_PRECEDING_AND_CURRENT_ROW,
-                            WindowFrameExclusion.EXCLUDE_NO_OTHERS);
+                    frame = null;
                 }
             } else {
                 frame = readWindowFrame();
@@ -3092,46 +3093,89 @@ public class Parser {
     }
 
     private WindowFrame readWindowFrame() {
-        SimpleExtent extent;
+        WindowFrameUnits units;
+        if (readIf("ROWS")) {
+            units = WindowFrameUnits.ROWS;
+        } else if (readIf("RANGE")) {
+            units = WindowFrameUnits.RANGE;
+        } else if (readIf("GROUPS")) {
+            units = WindowFrameUnits.GROUPS;
+        } else {
+            return null;
+        }
+        WindowFrameBound starting, following;
+        if (readIf("BETWEEN")) {
+            starting = readWindowFrameRange();
+            read("AND");
+            following = readWindowFrameRange();
+        } else {
+            starting = readWindowFrameStarting();
+            following = null;
+        }
+        int idx = lastParseIndex;
         WindowFrameExclusion exclusion = WindowFrameExclusion.EXCLUDE_NO_OTHERS;
-        if (readIf("RANGE")) {
-            read("BETWEEN");
-            if (readIf("UNBOUNDED")) {
-                read("PRECEDING");
-                read("AND");
-                if (readIf("CURRENT")) {
-                    read("ROW");
-                    extent = SimpleExtent.RANGE_BETWEEN_UNBOUNDED_PRECEDING_AND_CURRENT_ROW;
-                } else {
-                    read("UNBOUNDED");
-                    read("FOLLOWING");
-                    extent = SimpleExtent.RANGE_BETWEEN_UNBOUNDED_PRECEDING_AND_UNBOUNDED_FOLLOWING;
-                }
-            } else {
-                read("CURRENT");
+        if (readIf("EXCLUDE")) {
+            if (readIf("CURRENT")) {
                 read("ROW");
-                read("AND");
-                read("UNBOUNDED");
-                read("FOLLOWING");
-                extent = SimpleExtent.RANGE_BETWEEN_CURRENT_ROW_AND_UNBOUNDED_FOLLOWING;
-            }
-            if (readIf("EXCLUDE")) {
-                if (readIf("CURRENT")) {
-                    read("ROW");
-                    exclusion = WindowFrameExclusion.EXCLUDE_CURRENT_ROW;
-                } else if (readIf(GROUP)) {
-                    exclusion = WindowFrameExclusion.EXCLUDE_GROUP;
-                } else if (readIf("TIES")) {
-                    exclusion = WindowFrameExclusion.EXCLUDE_TIES;
-                } else {
-                    read("NO");
-                    read("OTHERS");
-                }
+                exclusion = WindowFrameExclusion.EXCLUDE_CURRENT_ROW;
+            } else if (readIf(GROUP)) {
+                exclusion = WindowFrameExclusion.EXCLUDE_GROUP;
+            } else if (readIf("TIES")) {
+                exclusion = WindowFrameExclusion.EXCLUDE_TIES;
+            } else {
+                read("NO");
+                read("OTHERS");
             }
-        } else {
-            extent = SimpleExtent.RANGE_BETWEEN_UNBOUNDED_PRECEDING_AND_CURRENT_ROW;
         }
-        return new WindowFrame(extent, exclusion);
+        WindowFrame frame = new WindowFrame(units, starting, following, exclusion);
+        if (!frame.isValid()) {
+            throw DbException.getSyntaxError(sqlCommand, idx);
+        }
+        return frame;
+    }
+
+    private WindowFrameBound readWindowFrameStarting() {
+        if (readIf("UNBOUNDED")) {
+            read("PRECEDING");
+            return new WindowFrameBound(WindowFrameBoundType.UNBOUNDED_PRECEDING, null);
+        }
+        if (readIf("CURRENT")) {
+            read("ROW");
+            return new WindowFrameBound(WindowFrameBoundType.CURRENT_ROW, null);
+        }
+        Expression value = readValueOrParameter();
+        read("PRECEDING");
+        return new WindowFrameBound(WindowFrameBoundType.PRECEDING, value);
+    }
+
+    private WindowFrameBound readWindowFrameRange() {
+        if (readIf("UNBOUNDED")) {
+            if (readIf("PRECEDING")) {
+                return new WindowFrameBound(WindowFrameBoundType.UNBOUNDED_PRECEDING, null);
+            }
+            read("FOLLOWING");
+            return new WindowFrameBound(WindowFrameBoundType.UNBOUNDED_FOLLOWING, null);
+        }
+        if (readIf("CURRENT")) {
+            read("ROW");
+            return new WindowFrameBound(WindowFrameBoundType.CURRENT_ROW, null);
+        }
+        Expression value = readValueOrParameter();
+        if (readIf("PRECEDING")) {
+            return new WindowFrameBound(WindowFrameBoundType.PRECEDING, value);
+        }
+        read("FOLLOWING");
+        return new WindowFrameBound(WindowFrameBoundType.FOLLOWING, value);
+    }
+
+    private Expression readValueOrParameter() {
+        int index = parseIndex;
+        Expression value = readExpression();
+        if (!(value instanceof ValueExpression) && !(value instanceof Parameter)) {
+            parseIndex = index;
+            throw getSyntaxError();
+        }
+        return value;
     }
 
     private AggregateType getAggregateType(String name) {

h2/src/main/org/h2/expression/aggregate/AbstractAggregate.java

@@ -445,7 +445,7 @@ public abstract class AbstractAggregate extends Expression {
             int size = ordered.size();
             for (int i = 0; i < size; i++) {
                 Object aggregateData = createAggregateData();
-                for (Iterator<Value[]> iter = frame.iterator(ordered, getOverOrderBySort(), i, false); iter
+                for (Iterator<Value[]> iter = frame.iterator(session, ordered, getOverOrderBySort(), i, false); iter
                         .hasNext();) {
                     updateFromExpressions(session, aggregateData, iter.next());
                 }

h2/src/main/org/h2/expression/aggregate/Window.java

@@ -64,6 +64,11 @@ public final class Window {
     public Window(ArrayList<Expression> partitionBy, ArrayList<SelectOrderBy> orderBy, WindowFrame frame) {
         this.partitionBy = partitionBy;
         this.orderBy = orderBy;
+        if (frame == null) {
+            frame = new WindowFrame(WindowFrameUnits.RANGE,
+                    new WindowFrameBound(WindowFrameBoundType.UNBOUNDED_PRECEDING, null), null,
+                    WindowFrameExclusion.EXCLUDE_NO_OTHERS);
+        }
         this.frame = frame;
     }
 

h2/src/main/org/h2/expression/aggregate/WindowFrame.java

@@ -11,6 +11,10 @@ import java.util.Collections;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 
+import org.h2.engine.Session;
+import org.h2.expression.BinaryOperation;
+import org.h2.expression.BinaryOperation.OpType;
+import org.h2.expression.ValueExpression;
 import org.h2.message.DbException;
 import org.h2.result.SortOrder;
 import org.h2.value.Value;
@@ -20,92 +24,6 @@ import org.h2.value.Value;
  */
 public final class WindowFrame {
 
-    /**
-     * Simple extent.
-     */
-    public enum SimpleExtent {
-
-    /**
-     * RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW frame specification.
-     */
-    RANGE_BETWEEN_UNBOUNDED_PRECEDING_AND_CURRENT_ROW("RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW"),
-
-    /**
-     * RANGE BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING frame specification.
-     */
-    RANGE_BETWEEN_CURRENT_ROW_AND_UNBOUNDED_FOLLOWING("RANGE BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING"),
-
-    /**
-     * RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING frame
-     * specification.
-     */
-    RANGE_BETWEEN_UNBOUNDED_PRECEDING_AND_UNBOUNDED_FOLLOWING(
-            "RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING"),
-
-        ;
-
-        private final String sql;
-
-        private SimpleExtent(String sql) {
-            this.sql = sql;
-        }
-
-        /**
-         * Returns SQL representation.
-         *
-         * @return SQL representation.
-         * @see org.h2.expression.Expression#getSQL()
-         */
-        public String getSQL() {
-            return sql;
-        }
-
-    }
-
-    /**
-     * Window frame exclusion clause.
-     */
-    public enum WindowFrameExclusion {
-        /**
-         * EXCLUDE CURRENT ROW exclusion clause.
-         */
-        EXCLUDE_CURRENT_ROW("EXCLUDE CURRENT ROW"),
-
-        /**
-         * EXCLUDE GROUP exclusion clause.
-         */
-        EXCLUDE_GROUP("EXCLUDE GROUP"),
-
-        /**
-         * EXCLUDE TIES exclusion clause.
-         */
-        EXCLUDE_TIES("EXCLUDE TIES"),
-
-        /**
-         * EXCLUDE NO OTHERS exclusion clause.
-         */
-        EXCLUDE_NO_OTHERS("EXCLUDE NO OTHERS"),
-
-        ;
-
-        private final String sql;
-
-        private WindowFrameExclusion(String sql) {
-            this.sql = sql;
-        }
-
-        /**
-         * Returns SQL representation.
-         *
-         * @return SQL representation.
-         * @see org.h2.expression.Expression#getSQL()
-         */
-        public String getSQL() {
-            return sql;
-        }
-
-    }
-
     private abstract class Itr implements Iterator<Value[]> {
 
         final ArrayList<Value[]> orderedRows;
@@ -231,30 +149,100 @@ public final class WindowFrame {
 
     }
 
-    private final SimpleExtent extent;
+    private final WindowFrameUnits units;
+
+    private final WindowFrameBound starting;
+
+    private final WindowFrameBound following;
 
     private final WindowFrameExclusion exclusion;
 
+    private static int toGroupStart(ArrayList<Value[]> orderedRows, SortOrder sortOrder, int offset, int minOffset) {
+        Value[] row = orderedRows.get(offset);
+        while (offset > minOffset && sortOrder.compare(row, orderedRows.get(offset - 1)) == 0) {
+            offset--;
+        }
+        return offset;
+    }
+
+    private static int toGroupEnd(ArrayList<Value[]> orderedRows, SortOrder sortOrder, int offset, int maxOffset) {
+        Value[] row = orderedRows.get(offset);
+        while (offset < maxOffset && sortOrder.compare(row, orderedRows.get(offset + 1)) == 0) {
+            offset++;
+        }
+        return offset;
+    }
+
+    private static int getIntOffset(WindowFrameBound bound, Session session) {
+        int value = bound.getValue().getValue(session).getInt();
+        if (value < 0) {
+            throw DbException.getInvalidValueException("unsigned", value);
+        }
+        return value;
+    }
+
+    private static Value[] getCompareRow(Session session, ArrayList<Value[]> orderedRows, SortOrder sortOrder,
+            int currentRow, WindowFrameBound bound, boolean add) {
+        int sortIndex = sortOrder.getQueryColumnIndexes()[0];
+        OpType opType = add ^ (sortOrder.getSortTypes()[0] & SortOrder.DESCENDING) != 0 ? OpType.PLUS : OpType.MINUS;
+        Value[] row = orderedRows.get(currentRow);
+        Value[] newRow = row.clone();
+        newRow[sortIndex] = new BinaryOperation(opType, //
+                ValueExpression.get(row[sortIndex]), ValueExpression.get(getValueOffset(bound, session))) //
+                        .optimize(session).getValue(session);
+        return newRow;
+    }
+
+    private static Value getValueOffset(WindowFrameBound bound, Session session) {
+        Value value = bound.getValue().getValue(session);
+        if (value.getSignum() < 0) {
+            throw DbException.getInvalidValueException("unsigned", value.getTraceSQL());
+        }
+        return value;
+    }
+
     /**
      * Creates new instance of window frame clause.
      *
-     * @param extent
-     *            window frame extent
+     * @param units
+     *            units
+     * @param starting
+     *            starting clause
+     * @param following
+     *            following clause
      * @param exclusion
-     *            window frame exclusion
+     *            exclusion clause
      */
-    public WindowFrame(SimpleExtent extent, WindowFrameExclusion exclusion) {
-        this.extent = extent;
+    public WindowFrame(WindowFrameUnits units, WindowFrameBound starting, WindowFrameBound following,
+            WindowFrameExclusion exclusion) {
+        this.units = units;
+        this.starting = starting;
+        if (following != null && following.getType() == WindowFrameBoundType.CURRENT_ROW) {
+            following = null;
+        }
+        this.following = following;
         this.exclusion = exclusion;
     }
 
+    /**
+     * Checks validity of this frame.
+     *
+     * @return whether bounds of this frame valid
+     */
+    public boolean isValid() {
+        WindowFrameBoundType s = starting.getType(),
+                f = following != null ? following.getType() : WindowFrameBoundType.CURRENT_ROW;
+        return s != WindowFrameBoundType.UNBOUNDED_FOLLOWING && f != WindowFrameBoundType.UNBOUNDED_PRECEDING
+                && s.compareTo(f) <= 0;
+    }
+
     /**
      * Returns whether window frame specification can be omitted.
      *
      * @return whether window frame specification can be omitted
      */
     public boolean isDefault() {
-        return extent == SimpleExtent.RANGE_BETWEEN_UNBOUNDED_PRECEDING_AND_CURRENT_ROW
+        return starting.getType() == WindowFrameBoundType.UNBOUNDED_PRECEDING && following == null
                 && exclusion == WindowFrameExclusion.EXCLUDE_NO_OTHERS;
     }
 
@@ -265,13 +253,16 @@ public final class WindowFrame {
      * @return whether window frame specification contains all rows in partition
      */
     public boolean isFullPartition() {
-        return extent == SimpleExtent.RANGE_BETWEEN_UNBOUNDED_PRECEDING_AND_UNBOUNDED_FOLLOWING
+        return starting.getType() == WindowFrameBoundType.UNBOUNDED_PRECEDING && following != null
+                && following.getType() == WindowFrameBoundType.UNBOUNDED_FOLLOWING
                 && exclusion == WindowFrameExclusion.EXCLUDE_NO_OTHERS;
     }
 
     /**
      * Returns iterator.
      *
+     * @param session
+     *            the session
      * @param orderedRows
      *            ordered rows
      * @param sortOrder
@@ -280,27 +271,26 @@ public final class WindowFrame {
      *            index of the current row
      * @param reverse
      *            whether iterator should iterate in reverse order
+     *
      * @return iterator
      */
-    public Iterator<Value[]> iterator(ArrayList<Value[]> orderedRows, SortOrder sortOrder, int currentRow,
-            boolean reverse) {
+    public Iterator<Value[]> iterator(Session session, ArrayList<Value[]> orderedRows, SortOrder sortOrder,
+            int currentRow, boolean reverse) {
+        int startIndex = getIndex(session, orderedRows, sortOrder, currentRow, starting, false);
+        int endIndex = following != null ? getIndex(session, orderedRows, sortOrder, currentRow, following, true)
+                : currentRow;
+        if (endIndex < startIndex) {
+            return Collections.emptyIterator();
+        }
         int size = orderedRows.size();
-        final int startIndex, endIndex;
-        switch (extent) {
-        case RANGE_BETWEEN_UNBOUNDED_PRECEDING_AND_CURRENT_ROW:
-            startIndex = 0;
-            endIndex = currentRow;
-            break;
-        case RANGE_BETWEEN_CURRENT_ROW_AND_UNBOUNDED_FOLLOWING:
-            startIndex = currentRow;
-            endIndex = size - 1;
-            break;
-        case RANGE_BETWEEN_UNBOUNDED_PRECEDING_AND_UNBOUNDED_FOLLOWING:
+        if (startIndex >= size || endIndex < 0) {
+            return Collections.emptyIterator();
+        }
+        if (startIndex < 0) {
             startIndex = 0;
+        }
+        if (endIndex >= size) {
             endIndex = size - 1;
-            break;
-        default:
-            throw DbException.getUnsupportedException("window frame extent =" + extent);
         }
         if (exclusion != WindowFrameExclusion.EXCLUDE_NO_OTHERS) {
             return complexIterator(orderedRows, sortOrder, currentRow, startIndex, endIndex, reverse);
@@ -309,6 +299,148 @@ public final class WindowFrame {
                 : new PlainItr(orderedRows, startIndex, endIndex);
     }
 
+    private int getIndex(Session session, ArrayList<Value[]> orderedRows, SortOrder sortOrder, int currentRow,
+            WindowFrameBound bound, boolean forFollowing) {
+        int size = orderedRows.size();
+        int last = size - 1;
+        int index;
+        switch (bound.getType()) {
+        case UNBOUNDED_PRECEDING:
+            index = -1;
+            break;
+        case PRECEDING:
+            switch (units) {
+            case ROWS: {
+                int value = getIntOffset(bound, session);
+                index = value > currentRow ? -1 : currentRow - value;
+                break;
+            }
+            case GROUPS: {
+                int value = getIntOffset(bound, session);
+                if (!forFollowing) {
+                    index = toGroupStart(orderedRows, sortOrder, currentRow, 0);
+                    while (value > 0 && index > 0) {
+                        value--;
+                        index = toGroupStart(orderedRows, sortOrder, index - 1, 0);
+                    }
+                    if (value > 0) {
+                        index = -1;
+                    }
+                } else {
+                    if (value == 0) {
+                        index = toGroupEnd(orderedRows, sortOrder, currentRow, last);
+                    } else {
+                        index = currentRow;
+                        while (value > 0 && index >= 0) {
+                            value--;
+                            index = toGroupStart(orderedRows, sortOrder, index, 0) - 1;
+                        }
+                    }
+                }
+                break;
+            }
+            case RANGE: {
+                index = currentRow;
+                Value[] row = getCompareRow(session, orderedRows, sortOrder, index, bound, false);
+                index = Collections.binarySearch(orderedRows, row, sortOrder);
+                if (index >= 0) {
+                    if (!forFollowing) {
+                        while (index > 0 && sortOrder.compare(row, orderedRows.get(index - 1)) == 0) {
+                            index--;
+                        }
+                    } else {
+                        while (index < last && sortOrder.compare(row, orderedRows.get(index + 1)) == 0) {
+                            index++;
+                        }
+                    }
+                } else {
+                    index = ~index;
+                    if (!forFollowing) {
+                        if (index == 0) {
+                            index = -1;
+                        }
+                    } else {
+                        index--;
+                    }
+                }
+                break;
+            }
+            default:
+                throw DbException.getUnsupportedException("units=" + units);
+            }
+            break;
+        case CURRENT_ROW:
+            index = currentRow;
+            break;
+        case FOLLOWING:
+            switch (units) {
+            case ROWS: {
+                int value = getIntOffset(bound, session);
+                int rem = last - currentRow;
+                index = value > rem ? size : currentRow + value;
+                break;
+            }
+            case GROUPS: {
+                int value = getIntOffset(bound, session);
+                if (forFollowing) {
+                    index = toGroupEnd(orderedRows, sortOrder, currentRow, last);
+                    while (value > 0 && index < last) {
+                        value--;
+                        index = toGroupEnd(orderedRows, sortOrder, index + 1, last);
+                    }
+                    if (value > 0) {
+                        index = size;
+                    }
+                } else {
+                    if (value == 0) {
+                        index = toGroupStart(orderedRows, sortOrder, currentRow, 0);
+                    } else {
+                        index = currentRow;
+                        while (value > 0 && index <= last) {
+                            value--;
+                            index = toGroupEnd(orderedRows, sortOrder, index, last) + 1;
+                        }
+                    }
+                }
+                break;
+            }
+            case RANGE: {
+                index = currentRow;
+                Value[] row = getCompareRow(session, orderedRows, sortOrder, index, bound, true);
+                index = Collections.binarySearch(orderedRows, row, sortOrder);
+                if (index >= 0) {
+                    if (forFollowing) {
+                        while (index < last && sortOrder.compare(row, orderedRows.get(index + 1)) == 0) {
+                            index++;
+                        }
+                    } else {
+                        while (index > 0 && sortOrder.compare(row, orderedRows.get(index - 1)) == 0) {
+                            index--;
+                        }
+                    }
+                } else {
+                    index = ~index;
+                    if (forFollowing) {
+                        if (index != size) {
+                            index--;
+                        }
+                    }
+                }
+                break;
+            }
+            default:
+                throw DbException.getUnsupportedException("units=" + units);
+            }
+            break;
+        case UNBOUNDED_FOLLOWING:
+            index = size;
+            break;
+        default:
+            throw DbException.getUnsupportedException("window frame bound type=" + bound.getType());
+        }
+        return index;
+    }
+
     private Iterator<Value[]> complexIterator(ArrayList<Value[]> orderedRows, SortOrder sortOrder, int currentRow,
             int startIndex, int endIndex, boolean reverse) {
         int size = orderedRows.size();
@@ -320,15 +452,8 @@ public final class WindowFrame {
             break;
         case EXCLUDE_GROUP:
         case EXCLUDE_TIES: {
-            int exStart = currentRow;
-            Value[] row = orderedRows.get(currentRow);
-            while (exStart > startIndex && sortOrder.compare(row, orderedRows.get(exStart - 1)) == 0) {
-                exStart--;
-            }
-            int exEnd = currentRow;
-            while (exEnd < endIndex && sortOrder.compare(row, orderedRows.get(exEnd + 1)) == 0) {
-                exEnd++;
-            }
+            int exStart = toGroupStart(orderedRows, sortOrder, currentRow, startIndex);
+            int exEnd = toGroupEnd(orderedRows, sortOrder, currentRow, endIndex);
             set.clear(exStart, exEnd + 1);
             if (exclusion == WindowFrameExclusion.EXCLUDE_TIES) {
                 set.set(currentRow);
@@ -350,11 +475,17 @@ public final class WindowFrame {
      * @see org.h2.expression.Expression#getSQL()
      */
     public String getSQL() {
-        String sql = extent.getSQL();
+        StringBuilder builder = new StringBuilder();
+        builder.append(units.getSQL());
+        if (following == null) {
+            builder.append(' ').append(starting.getSQL(false));
+        } else {
+            builder.append(" BETWEEN ").append(starting.getSQL(false)).append(" AND ").append(following.getSQL(true));
+        }
         if (exclusion != WindowFrameExclusion.EXCLUDE_NO_OTHERS) {
-            sql = sql + ' ' + exclusion.getSQL();
+            builder.append(' ').append(exclusion.getSQL());
         }
-        return sql;
+        return builder.toString();
     }
 
 }

h2/src/main/org/h2/expression/aggregate/WindowFrameBound.java

+/*
+ * Copyright 2004-2018 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.expression.aggregate;
+
+import org.h2.expression.Expression;
+
+/**
+ * Window frame bound.
+ */
+public class WindowFrameBound {
+
+    private final WindowFrameBoundType type;
+
+    private final Expression value;
+
+    /**
+     * Creates new instance of window frame bound.
+     *
+     * @param type
+     *            bound type
+     * @param value
+     *            bound value, if any
+     */
+    public WindowFrameBound(WindowFrameBoundType type, Expression value) {
+        this.type = type;
+        if (type == WindowFrameBoundType.PRECEDING || type == WindowFrameBoundType.FOLLOWING) {
+            this.value = value;
+        } else {
+            this.value = null;
+        }
+    }
+
+    /**
+     * Returns the type
+     *
+     * @return the type
+     */
+    public WindowFrameBoundType getType() {
+        return type;
+    }
+
+    /**
+     * Returns the value.
+     *
+     * @return the value
+     */
+    public Expression getValue() {
+        return value;
+    }
+
+    /**
+     * Returns SQL representation.
+     *
+     * @param following
+     *            if false return SQL for starting clause, if true return SQL
+     *            for following clause
+     * @return SQL representation.
+     * @see Expression#getSQL()
+     */
+    public String getSQL(boolean following) {
+        if (type == WindowFrameBoundType.PRECEDING || type == WindowFrameBoundType.FOLLOWING) {
+            return value.getSQL() + ' ' + type.getSQL();
+        }
+        return type.getSQL();
+    }
+
+}

h2/src/main/org/h2/expression/aggregate/WindowFrameBoundType.java

+/*
+ * Copyright 2004-2018 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.expression.aggregate;
+
+/**
+ * Window frame bound type.
+ */
+public enum WindowFrameBoundType {
+
+    /**
+     * UNBOUNDED PRECEDING clause.
+     */
+    UNBOUNDED_PRECEDING("UNBOUNDED PRECEDING"),
+
+    /**
+     * PRECEDING clause.
+     */
+    PRECEDING("PRECEDING"),
+
+    /**
+     * CURRENT_ROW clause.
+     */
+    CURRENT_ROW("CURRENT_ROW"),
+
+    /**
+     * FOLLOWING clause.
+     */
+    FOLLOWING("FOLLOWING"),
+
+    /**
+     * UNBOUNDED FOLLOWING clause.
+     */
+    UNBOUNDED_FOLLOWING("UNBOUNDED FOLLOWING");
+
+    private final String sql;
+
+    private WindowFrameBoundType(String sql) {
+        this.sql = sql;
+    }
+
+    /**
+     * Returns SQL representation.
+     *
+     * @return SQL representation.
+     * @see org.h2.expression.Expression#getSQL()
+     */
+    public String getSQL() {
+        return sql;
+    }
+
+}

h2/src/main/org/h2/expression/aggregate/WindowFrameExclusion.java

+/*
+ * Copyright 2004-2018 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.expression.aggregate;
+
+/**
+ * Window frame exclusion clause.
+ */
+public enum WindowFrameExclusion {
+
+    /**
+     * EXCLUDE CURRENT ROW exclusion clause.
+     */
+    EXCLUDE_CURRENT_ROW("EXCLUDE CURRENT ROW"),
+
+    /**
+     * EXCLUDE GROUP exclusion clause.
+     */
+    EXCLUDE_GROUP("EXCLUDE GROUP"),
+
+    /**
+     * EXCLUDE TIES exclusion clause.
+     */
+    EXCLUDE_TIES("EXCLUDE TIES"),
+
+    /**
+     * EXCLUDE NO OTHERS exclusion clause.
+     */
+    EXCLUDE_NO_OTHERS("EXCLUDE NO OTHERS"),
+
+    ;
+
+    private final String sql;
+
+    private WindowFrameExclusion(String sql) {
+        this.sql = sql;
+    }
+
+    /**
+     * Returns SQL representation.
+     *
+     * @return SQL representation.
+     * @see org.h2.expression.Expression#getSQL()
+     */
+    public String getSQL() {
+        return sql;
+    }
+
+}

h2/src/main/org/h2/expression/aggregate/WindowFrameUnits.java

+/*
+ * Copyright 2004-2018 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.expression.aggregate;
+
+/**
+ * Window frame units.
+ */
+public enum WindowFrameUnits {
+
+    /**
+     * ROWS unit.
+     */
+    ROWS,
+
+    /**
+     * RANGE unit.
+     */
+    RANGE,
+
+    /**
+     * GROUPS unit.
+     */
+    GROUPS,
+
+    ;
+
+    /**
+     * Returns SQL representation.
+     *
+     * @return SQL representation.
+     * @see org.h2.expression.Expression#getSQL()
+     */
+    public String getSQL() {
+        return name();
+    }
+
+}

h2/src/main/org/h2/expression/aggregate/WindowFunction.java

@@ -321,11 +321,11 @@ public class WindowFunction extends AbstractAggregate {
             Value v;
             switch (type) {
             case FIRST_VALUE: {
-                v = getNthValue(frame.iterator(ordered, getOverOrderBySort(), i, false), 0, ignoreNulls);
+                v = getNthValue(frame.iterator(session, ordered, getOverOrderBySort(), i, false), 0, ignoreNulls);
                 break;
             }
             case LAST_VALUE:
-                v = getNthValue(frame.iterator(ordered, getOverOrderBySort(), i, true), 0, ignoreNulls);
+                v = getNthValue(frame.iterator(session, ordered, getOverOrderBySort(), i, true), 0, ignoreNulls);
                 break;
             case NTH_VALUE: {
                 int n = row[1].getInt();
@@ -333,7 +333,7 @@ public class WindowFunction extends AbstractAggregate {
                     throw DbException.getInvalidValueException("nth row", n);
                 }
                 n--;
-                Iterator<Value[]> iter = frame.iterator(ordered, getOverOrderBySort(), i, fromLast);
+                Iterator<Value[]> iter = frame.iterator(session, ordered, getOverOrderBySort(), i, fromLast);
                 v = getNthValue(iter, n, ignoreNulls);
                 break;
             }

h2/src/test/org/h2/test/scripts/functions/aggregate/array-agg.sql

@@ -275,3 +275,160 @@ SELECT
 
 DROP TABLE TEST;
 > ok
+
+CREATE TABLE TEST(ID INT, VALUE INT);
+> ok
+
+INSERT INTO TEST VALUES
+    (1, 1),
+    (2, 1),
+    (3, 5),
+    (4, 8),
+    (5, 8),
+    (6, 8),
+    (7, 9),
+    (8, 9);
+> update count: 8
+
+SELECT *,
+    ARRAY_AGG(ID) OVER (ORDER BY VALUE ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING) R_ID,
+    ARRAY_AGG(VALUE) OVER (ORDER BY VALUE ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING) R_V,
+    ARRAY_AGG(ID) OVER (ORDER BY VALUE RANGE BETWEEN 1 PRECEDING AND 1 FOLLOWING) V_ID,
+    ARRAY_AGG(VALUE) OVER (ORDER BY VALUE RANGE BETWEEN 1 PRECEDING AND 1 FOLLOWING) V_V,
+    ARRAY_AGG(VALUE) OVER (ORDER BY VALUE DESC RANGE BETWEEN 1 PRECEDING AND 1 FOLLOWING) V_V_R,
+    ARRAY_AGG(ID) OVER (ORDER BY VALUE GROUPS BETWEEN 1 PRECEDING AND 1 FOLLOWING) G_ID,
+    ARRAY_AGG(VALUE) OVER (ORDER BY VALUE GROUPS BETWEEN 1 PRECEDING AND 1 FOLLOWING) G_V
+    FROM TEST;
+> ID VALUE R_ID      R_V       V_ID            V_V             V_V_R           G_ID               G_V
+> -- ----- --------- --------- --------------- --------------- --------------- ------------------ ------------------
+> 1  1     (1, 2)    (1, 1)    (1, 2)          (1, 1)          (1, 1)          (1, 2, 3)          (1, 1, 5)
+> 2  1     (1, 2, 3) (1, 1, 5) (1, 2)          (1, 1)          (1, 1)          (1, 2, 3)          (1, 1, 5)
+> 3  5     (2, 3, 4) (1, 5, 8) (3)             (5)             (5)             (1, 2, 3, 4, 5, 6) (1, 1, 5, 8, 8, 8)
+> 4  8     (3, 4, 5) (5, 8, 8) (4, 5, 6, 7, 8) (8, 8, 8, 9, 9) (9, 9, 8, 8, 8) (3, 4, 5, 6, 7, 8) (5, 8, 8, 8, 9, 9)
+> 5  8     (4, 5, 6) (8, 8, 8) (4, 5, 6, 7, 8) (8, 8, 8, 9, 9) (9, 9, 8, 8, 8) (3, 4, 5, 6, 7, 8) (5, 8, 8, 8, 9, 9)
+> 6  8     (5, 6, 7) (8, 8, 9) (4, 5, 6, 7, 8) (8, 8, 8, 9, 9) (9, 9, 8, 8, 8) (3, 4, 5, 6, 7, 8) (5, 8, 8, 8, 9, 9)
+> 7  9     (6, 7, 8) (8, 9, 9) (4, 5, 6, 7, 8) (8, 8, 8, 9, 9) (9, 9, 8, 8, 8) (4, 5, 6, 7, 8)    (8, 8, 8, 9, 9)
+> 8  9     (7, 8)    (9, 9)    (4, 5, 6, 7, 8) (8, 8, 8, 9, 9) (9, 9, 8, 8, 8) (4, 5, 6, 7, 8)    (8, 8, 8, 9, 9)
+> rows (ordered): 8
+
+SELECT *, ARRAY_AGG(ID) OVER (ORDER BY VALUE ROWS -1 PRECEDING) FROM TEST;
+> exception INVALID_VALUE_2
+
+SELECT *, ARRAY_AGG(ID) OVER (ORDER BY ID ROWS BETWEEN 2 PRECEDING AND 1 PRECEDING) FROM TEST FETCH FIRST 4 ROWS ONLY;
+> ID VALUE ARRAY_AGG(ID) OVER (ORDER BY ID ROWS BETWEEN 2 PRECEDING AND 1 PRECEDING)
+> -- ----- -------------------------------------------------------------------------
+> 1  1     null
+> 2  1     (1)
+> 3  5     (1, 2)
+> 4  8     (2, 3)
+> rows (ordered): 4
+
+SELECT *, ARRAY_AGG(ID) OVER (ORDER BY ID ROWS BETWEEN 1 FOLLOWING AND 2 FOLLOWING) FROM TEST OFFSET 4 ROWS;
+> ID VALUE ARRAY_AGG(ID) OVER (ORDER BY ID ROWS BETWEEN 1 FOLLOWING AND 2 FOLLOWING)
+> -- ----- -------------------------------------------------------------------------
+> 5  8     (6, 7)
+> 6  8     (7, 8)
+> 7  9     (8)
+> 8  9     null
+> rows (ordered): 4
+
+SELECT *, ARRAY_AGG(ID) OVER (ORDER BY ID RANGE BETWEEN 2 PRECEDING AND 1 PRECEDING) FROM TEST FETCH FIRST 4 ROWS ONLY;
+> ID VALUE ARRAY_AGG(ID) OVER (ORDER BY ID RANGE BETWEEN 2 PRECEDING AND 1 PRECEDING)
+> -- ----- --------------------------------------------------------------------------
+> 1  1     null
+> 2  1     (1)
+> 3  5     (1, 2)
+> 4  8     (2, 3)
+> rows (ordered): 4
+
+SELECT *, ARRAY_AGG(ID) OVER (ORDER BY ID RANGE BETWEEN 1 FOLLOWING AND 2 FOLLOWING) FROM TEST OFFSET 4 ROWS;
+> ID VALUE ARRAY_AGG(ID) OVER (ORDER BY ID RANGE BETWEEN 1 FOLLOWING AND 2 FOLLOWING)
+> -- ----- --------------------------------------------------------------------------
+> 5  8     (6, 7)
+> 6  8     (7, 8)
+> 7  9     (8)
+> 8  9     null
+> rows (ordered): 4
+
+SELECT *,
+    ARRAY_AGG(ID) OVER (ORDER BY VALUE GROUPS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING) U_P,
+    ARRAY_AGG(ID) OVER (ORDER BY VALUE GROUPS BETWEEN 2 PRECEDING AND 1 PRECEDING) P,
+    ARRAY_AGG(ID) OVER (ORDER BY VALUE GROUPS BETWEEN 1 FOLLOWING AND 2 FOLLOWING) F,
+    ARRAY_AGG(ID) OVER (ORDER BY VALUE GROUPS BETWEEN 1 FOLLOWING AND UNBOUNDED FOLLOWING) U_F
+    FROM TEST;
+> ID VALUE U_P                P            F               U_F
+> -- ----- ------------------ ------------ --------------- ------------------
+> 1  1     null               null         (3, 4, 5, 6)    (3, 4, 5, 6, 7, 8)
+> 2  1     null               null         (3, 4, 5, 6)    (3, 4, 5, 6, 7, 8)
+> 3  5     (1, 2)             (1, 2)       (4, 5, 6, 7, 8) (4, 5, 6, 7, 8)
+> 4  8     (1, 2, 3)          (1, 2, 3)    (7, 8)          (7, 8)
+> 5  8     (1, 2, 3)          (1, 2, 3)    (7, 8)          (7, 8)
+> 6  8     (1, 2, 3)          (1, 2, 3)    (7, 8)          (7, 8)
+> 7  9     (1, 2, 3, 4, 5, 6) (3, 4, 5, 6) null            null
+> 8  9     (1, 2, 3, 4, 5, 6) (3, 4, 5, 6) null            null
+> rows (ordered): 8
+
+SELECT *,
+    ARRAY_AGG(ID) OVER (ORDER BY VALUE GROUPS BETWEEN 1 PRECEDING AND 0 PRECEDING) P,
+    ARRAY_AGG(ID) OVER (ORDER BY VALUE GROUPS BETWEEN 0 FOLLOWING AND 1 FOLLOWING) F
+    FROM TEST;
+> ID VALUE P               F
+> -- ----- --------------- ---------------
+> 1  1     (1, 2)          (1, 2, 3)
+> 2  1     (1, 2)          (1, 2, 3)
+> 3  5     (1, 2, 3)       (3, 4, 5, 6)
+> 4  8     (3, 4, 5, 6)    (4, 5, 6, 7, 8)
+> 5  8     (3, 4, 5, 6)    (4, 5, 6, 7, 8)
+> 6  8     (3, 4, 5, 6)    (4, 5, 6, 7, 8)
+> 7  9     (4, 5, 6, 7, 8) (7, 8)
+> 8  9     (4, 5, 6, 7, 8) (7, 8)
+> rows (ordered): 8
+
+SELECT *, ARRAY_AGG(ID) OVER (ORDER BY ID RANGE BETWEEN CURRENT ROW AND 1 PRECEDING) FROM TEST;
+> exception SYNTAX_ERROR_1
+
+DROP TABLE TEST;
+> ok
+
+CREATE TABLE TEST (ID INT, VALUE INT);
+> ok
+
+INSERT INTO TEST VALUES
+  (1, 1),
+  (2, 1),
+  (3, 2),
+  (4, 2),
+  (5, 3),
+  (6, 3),
+  (7, 4),
+  (8, 4);
+> update count: 8
+
+SELECT *, ARRAY_AGG(ID) OVER (ORDER BY VALUE RANGE BETWEEN 2 PRECEDING AND 1 PRECEDING) FROM TEST;
+> ID VALUE ARRAY_AGG(ID) OVER (ORDER BY VALUE RANGE BETWEEN 2 PRECEDING AND 1 PRECEDING)
+> -- ----- -----------------------------------------------------------------------------
+> 1  1     null
+> 2  1     null
+> 3  2     (1, 2)
+> 4  2     (1, 2)
+> 5  3     (1, 2, 3, 4)
+> 6  3     (1, 2, 3, 4)
+> 7  4     (3, 4, 5, 6)
+> 8  4     (3, 4, 5, 6)
+> rows (ordered): 8
+
+SELECT *, ARRAY_AGG(ID) OVER (ORDER BY VALUE RANGE BETWEEN 1 FOLLOWING AND 2 FOLLOWING) FROM TEST;
+> ID VALUE ARRAY_AGG(ID) OVER (ORDER BY VALUE RANGE BETWEEN 1 FOLLOWING AND 2 FOLLOWING)
+> -- ----- -----------------------------------------------------------------------------
+> 1  1     (3, 4, 5, 6)
+> 2  1     (3, 4, 5, 6)
+> 3  2     (5, 6, 7, 8)
+> 4  2     (5, 6, 7, 8)
+> 5  3     (7, 8)
+> 6  3     (7, 8)
+> 7  4     null
+> 8  4     null
+> rows (ordered): 8
+
+DROP TABLE TEST;
+> ok

h2/src/test/org/h2/test/scripts/functions/window/nth_value.sql

@@ -139,8 +139,8 @@ SELECT ID, CATEGORY,
     NTH_VALUE(CATEGORY, 2) OVER (ORDER BY CATEGORY RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) C,
     NTH_VALUE(CATEGORY, 2) OVER (ORDER BY CATEGORY RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW EXCLUDE CURRENT ROW)
     FROM TEST FETCH FIRST 3 ROWS ONLY;
-> ID CATEGORY C    NTH_VALUE(CATEGORY, 2) OVER (ORDER BY CATEGORY RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW EXCLUDE CURRENT ROW)
-> -- -------- ---- ---------------------------------------------------------------------------------------------------------------------
+> ID CATEGORY C    NTH_VALUE(CATEGORY, 2) OVER (ORDER BY CATEGORY RANGE UNBOUNDED PRECEDING EXCLUDE CURRENT ROW)
+> -- -------- ---- ---------------------------------------------------------------------------------------------
 > 1  1        null null
 > 2  1        1    null
 > 3  1        1    1