Add WINDOW clause support

8863b2db · Evgenij Ryazanov · 3b4620a2 · 8863b2db · 8863b2db · 8863b2db
--- a/h2/src/docsrc/help/help.csv
+++ b/h2/src/docsrc/help/help.csv
@@ -8,6 +8,7 @@ SELECT [ TOP term [ PERCENT ] [ WITH TIES ] ]
 selectExpression [,...]
 FROM tableExpression [,...] [ WHERE expression ]
 [ GROUP BY expression [,...] ] [ HAVING expression ]
+[ WINDOW { { windowName AS windowSpecification } [,...] } ]
 [ { UNION [ ALL ] | MINUS | EXCEPT | INTERSECT } select ]
 [ ORDER BY order [,...] ]
 [ LIMIT expression [ OFFSET expression ] [ SAMPLE_SIZE rowCountInt ] ]
@@ -2533,17 +2534,27 @@ The column list of the resulting table is C1, C2, and so on.
 SELECT * FROM (VALUES(1, 'Hello'), (2, 'World')) AS V;
 "

-"Other Grammar","Window specification","
-([PARTITION BY expression [,...]] [ORDER BY order [,...]]
-[windowFrame])
+"Other Grammar","Window name or specification","
+windowName | windowSpecification
 ","
-A window specification for a window function or aggregate.
+A window name or inline specification for a window function or aggregate.

 Window functions are currently experimental in H2 and should be used with caution.
 They also may require a lot of memory for large queries.
 ","
-()
+W1
 (ORDER BY ID)
+"
+
+"Other Grammar","Window specification","
+([existingWindowName]
+[PARTITION BY expression [,...]] [ORDER BY order [,...]]
+[windowFrame])
+","
+A window specification for a window, window function or aggregate.
+","
+()
+(W1 ORDER BY ID)
 (PARTITION BY CATEGORY)
 (PARTITION BY CATEGORY ORDER BY NAME, ID)
 (ORDER BY Y RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW EXCLUDE TIES)
@@ -3303,7 +3314,7 @@ INTERVAL MINUTE TO SECOND

 "Functions (Aggregate)","AVG","
 AVG ( [ DISTINCT ] { numeric } )
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 The average (mean) value.
 If no rows are selected, the result is NULL.
@@ -3315,7 +3326,7 @@ AVG(X)

 "Functions (Aggregate)","BIT_AND","
 BIT_AND(expression)
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 The bitwise AND of all non-null values.
 If no rows are selected, the result is NULL.
@@ -3326,7 +3337,7 @@ BIT_AND(ID)

 "Functions (Aggregate)","BIT_OR","
 BIT_OR(expression)
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 The bitwise OR of all non-null values.
 If no rows are selected, the result is NULL.
@@ -3337,7 +3348,7 @@ BIT_OR(ID)

 "Functions (Aggregate)","BOOL_AND","
 BOOL_AND(boolean)
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 Returns true if all expressions are true.
 If no rows are selected, the result is NULL.
@@ -3348,7 +3359,7 @@ BOOL_AND(ID>10)

 "Functions (Aggregate)","BOOL_OR","
 BOOL_OR(boolean)
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 Returns true if any expression is true.
 If no rows are selected, the result is NULL.
@@ -3359,7 +3370,7 @@ BOOL_OR(NAME LIKE 'W%')

 "Functions (Aggregate)","COUNT","
 COUNT( { * | { [ DISTINCT ] expression } } )
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 The count of all row, or of the non-null values.
 This method returns a long.
@@ -3373,7 +3384,7 @@ COUNT(*)
 GROUP_CONCAT ( [ DISTINCT ] string
 [ ORDER BY { expression [ ASC | DESC ] } [,...] ]
 [ SEPARATOR expression ] )
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 Concatenates strings with a separator.
 The default separator is a ',' (without space).
@@ -3387,7 +3398,7 @@ GROUP_CONCAT(NAME ORDER BY ID SEPARATOR ', ')
 "Functions (Aggregate)","ARRAY_AGG","
 ARRAY_AGG ( [ DISTINCT ] string
 [ ORDER BY { expression [ ASC | DESC ] } [,...] ] )
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 Aggregate the value into an array.
 This method returns an array.
@@ -3399,7 +3410,7 @@ ARRAY_AGG(NAME ORDER BY ID)

 "Functions (Aggregate)","MAX","
 MAX(value)
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 The highest value.
 If no rows are selected, the result is NULL.
@@ -3411,7 +3422,7 @@ MAX(NAME)

 "Functions (Aggregate)","MIN","
 MIN(value)
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 The lowest value.
 If no rows are selected, the result is NULL.
@@ -3423,7 +3434,7 @@ MIN(NAME)

 "Functions (Aggregate)","SUM","
 SUM( [ DISTINCT ] { numeric } )
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 The sum of all values.
 If no rows are selected, the result is NULL.
@@ -3436,7 +3447,7 @@ SUM(X)

 "Functions (Aggregate)","SELECTIVITY","
 SELECTIVITY(value)
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 Estimates the selectivity (0-100) of a value.
 The value is defined as (100 * distinctCount / rowCount).
@@ -3449,7 +3460,7 @@ SELECT SELECTIVITY(FIRSTNAME), SELECTIVITY(NAME) FROM TEST WHERE ROWNUM()<20000

 "Functions (Aggregate)","STDDEV_POP","
 STDDEV_POP( [ DISTINCT ] numeric )
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 The population standard deviation.
 This method returns a double.
@@ -3461,7 +3472,7 @@ STDDEV_POP(X)

 "Functions (Aggregate)","STDDEV_SAMP","
 STDDEV_SAMP( [ DISTINCT ] numeric )
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 The sample standard deviation.
 This method returns a double.
@@ -3473,7 +3484,7 @@ STDDEV(X)

 "Functions (Aggregate)","VAR_POP","
 VAR_POP( [ DISTINCT ] numeric )
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 The population variance (square of the population standard deviation).
 This method returns a double.
@@ -3485,7 +3496,7 @@ VAR_POP(X)

 "Functions (Aggregate)","VAR_SAMP","
 VAR_SAMP( [ DISTINCT ] numeric )
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 The sample variance (square of the sample standard deviation).
 This method returns a double.
@@ -3497,7 +3508,7 @@ VAR_SAMP(X)

 "Functions (Aggregate)","MEDIAN","
 MEDIAN( [ DISTINCT ] value )
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 The value separating the higher half of a values from the lower half.
 Returns the middle value or an interpolated value between two middle values if number of values is even.
@@ -3512,7 +3523,7 @@ MEDIAN(X)
 "Functions (Aggregate)","MODE","
 { MODE( value ) [ ORDER BY expression [ ASC | DESC ] ] }
    | { MODE() WITHIN GROUP(ORDER BY expression [ ASC | DESC ]) }
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 Returns the value that occurs with the greatest frequency.
 If there are multiple values with the same frequency only one value will be returned.
@@ -3532,7 +3543,7 @@ MODE() WITHIN GROUP(ORDER BY X)

 "Functions (Aggregate)","ENVELOPE","
 ENVELOPE( value )
-[FILTER (WHERE expression)] [OVER windowSpecification]
+[FILTER (WHERE expression)] [OVER windowNameOrSpecification]
 ","
 Returns the minimum bounding box that encloses all specified GEOMETRY values.
 Only 2D coordinate plane is supported.
@@ -5105,7 +5116,7 @@ H2VERSION()
 "

 "Functions (Window)","ROW_NUMBER","
-ROW_NUMBER() OVER windowSpecification
+ROW_NUMBER() OVER windowNameOrSpecification
 ","
 Returns the number of the current row starting with 1.

@@ -5118,7 +5129,7 @@ SELECT ROW_NUMBER() OVER (PARTITION BY CATEGORY ORDER BY ID), * FROM TEST;
 "

 "Functions (Window)","RANK","
-RANK() OVER windowSpecification
+RANK() OVER windowNameOrSpecification
 ","
 Returns the rank of the current row.
 The rank of a row is the number of rows that precede this row plus 1.
@@ -5133,7 +5144,7 @@ SELECT RANK() OVER (PARTITION BY CATEGORY ORDER BY ID), * FROM TEST;
 "

 "Functions (Window)","DENSE_RANK","
-DENSE_RANK() OVER windowSpecification
+DENSE_RANK() OVER windowNameOrSpecification
 ","
 Returns the dense rank of the current row.
 The rank of a row is the number of groups of rows with the same values in ORDER BY columns that precede group with this row plus 1.
@@ -5148,7 +5159,7 @@ SELECT DENSE_RANK() OVER (PARTITION BY CATEGORY ORDER BY ID), * FROM TEST;
 "

 "Functions (Window)","PERCENT_RANK","
-PERCENT_RANK() OVER windowSpecification
+PERCENT_RANK() OVER windowNameOrSpecification
 ","
 Returns the relative rank of the current row.
 The relative rank is calculated as (RANK - 1) / (NR - 1),
@@ -5162,7 +5173,7 @@ SELECT PERCENT_RANK() OVER (PARTITION BY CATEGORY ORDER BY ID), * FROM TEST;
 "

 "Functions (Window)","CUME_DIST","
-CUME_DIST() OVER windowSpecification
+CUME_DIST() OVER windowNameOrSpecification
 ","
 Returns the relative rank of the current row.
 The relative rank is calculated as NP / NR
@@ -5177,7 +5188,7 @@ SELECT CUME_DIST() OVER (PARTITION BY CATEGORY ORDER BY ID), * FROM TEST;
 "

 "Functions (Window)","NTILE","
-NTILE(int) OVER windowSpecification
+NTILE(int) OVER windowNameOrSpecification
 ","
 Distributes the rows into a specified number of groups.
 Number of groups should be a positive integer value.
@@ -5194,7 +5205,7 @@ SELECT NTILE(5) OVER (PARTITION BY CATEGORY ORDER BY ID), * FROM TEST;

 "Functions (Window)","LEAD","
 LEAD(value [, offsetInt [, defaultValue]]) [{RESPECT|IGNORE} NULLS]
-OVER windowSpecification
+OVER windowNameOrSpecification
 ","
 Returns the value in a next row with specified offset relative to the current row.
 Offset must be non-negative.
@@ -5214,7 +5225,7 @@ SELECT LEAD(X, 2, 0) IGNORE NULLS OVER (

 "Functions (Window)","LAG","
 LAG(value [, offsetInt [, defaultValue]]) [{RESPECT|IGNORE} NULLS]
-OVER windowSpecification
+OVER windowNameOrSpecification
 ","
 Returns the value in a previous row with specified offset relative to the current row.
 Offset must be non-negative.
@@ -5233,7 +5244,8 @@ SELECT LAG(X, 2, 0) IGNORE NULLS OVER (
 "

 "Functions (Window)","FIRST_VALUE","
-FIRST_VALUE(value) [{RESPECT|IGNORE} NULLS] OVER windowSpecification
+FIRST_VALUE(value) [{RESPECT|IGNORE} NULLS]
+OVER windowNameOrSpecification
 ","
 Returns the first value in a window.
 If IGNORE NULLS is specified null values are skipped and the function returns first non-null value, if any.
@@ -5246,7 +5258,8 @@ SELECT FIRST_VALUE(X) IGNORE NULLS OVER (PARTITION BY CATEGORY ORDER BY ID), * F
 "

 "Functions (Window)","LAST_VALUE","
-LAST_VALUE(value) [{RESPECT|IGNORE} NULLS] OVER windowSpecification
+LAST_VALUE(value) [{RESPECT|IGNORE} NULLS]
+OVER windowNameOrSpecification
 ","
 Returns the last value in a window.
 If IGNORE NULLS is specified null values are skipped and the function returns last non-null value before them, if any;
@@ -5265,7 +5278,7 @@ SELECT LAST_VALUE(X) IGNORE NULLS OVER (

 "Functions (Window)","NTH_VALUE","
 NTH_VALUE(value, nInt) [FROM {FIRST|LAST}] [{RESPECT|IGNORE} NULLS]
-OVER windowSpecification
+OVER windowNameOrSpecification
 ","
 Returns the value in a row with a specified relative number in a window.
 Relative row number must be positive.

--- a/h2/src/docsrc/html/advanced.html
+++ b/h2/src/docsrc/html/advanced.html
@@ -488,7 +488,7 @@ ALL, CHECK, CONSTRAINT, CROSS, CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, DI
 EXISTS, FALSE, FETCH, FOR, FOREIGN, FROM, FULL, GROUP, HAVING, INNER, INTERSECT, INTERSECTS,
 IS, JOIN, LIKE, LIMIT, LOCALTIME, LOCALTIMESTAMP, MINUS, NATURAL, NOT, NULL, OFFSET, ON, ORDER,
 PRIMARY, ROWNUM, SELECT, SYSDATE, SYSTIME, SYSTIMESTAMP, TODAY, TOP, TRUE, UNION, UNIQUE, WHERE,
-WITH
+WINDOW, WITH
 </code>
 </p><p>
 Certain words of this list are keywords because they are functions that can be used without '()' for compatibility,

--- a/h2/src/docsrc/textbase/_messages_en.prop
+++ b/h2/src/docsrc/textbase/_messages_en.prop
@@ -166,7 +166,7 @@
 90133=Cannot change the setting {0} when the database is already open
 90134=Access to the class {0} is denied
 90135=The database is open in exclusive mode; can not open additional connections
-90136=Unsupported outer join condition: {0}
+90136=Window not found: {0}
 90137=Can only assign to a variable, not to: {0}
 90138=Invalid database name: {0}
 90139=The public static Java method was not found: {0}

--- a/h2/src/main/org/h2/api/ErrorCode.java
+++ b/h2/src/main/org/h2/api/ErrorCode.java
@@ -1926,6 +1926,16 @@ public class ErrorCode {
     */
    public static final int DATABASE_IS_IN_EXCLUSIVE_MODE = 90135;

+    /**
+     * The error with code <code>90136</code> is thrown when
+     * trying to reference a window that does not exist.
+     * Example:
+     * <pre>
+     * SELECT LEAD(X) OVER W FROM TEST;
+     * </pre>
+     */
+    public static final int WINDOW_NOT_FOUND_1 = 90136;
+
    /**
     * The error with code <code>90137</code> is thrown when
     * trying to assign a value to something that is not a variable.
@@ -2009,7 +2019,7 @@ public class ErrorCode {
    public static final int AUTHENTICATOR_NOT_AVAILABLE = 90144;


-    // next are 90136, 90145
+    // next is 90145

    private ErrorCode() {
        // utility class

--- a/h2/src/main/org/h2/command/Parser.java
+++ b/h2/src/main/org/h2/command/Parser.java
@@ -44,6 +44,7 @@ import static org.h2.util.ParserUtil.TRUE;
 import static org.h2.util.ParserUtil.UNION;
 import static org.h2.util.ParserUtil.UNIQUE;
 import static org.h2.util.ParserUtil.WHERE;
+import static org.h2.util.ParserUtil.WINDOW;
 import static org.h2.util.ParserUtil.WITH;

 import java.math.BigDecimal;
@@ -482,6 +483,8 @@ public class Parser {
            "UNIQUE",
            // WHERE
            "WHERE",
+            // WINDOW
+            "WINDOW",
            // WITH
            "WITH",
            // PARAMETER
@@ -2628,6 +2631,17 @@ public class Parser {
            Expression condition = readExpression();
            command.setHaving(condition);
        }
+        if (readIf(WINDOW)) {
+            do {
+                int index = parseIndex;
+                String name = readAliasIdentifier();
+                read("AS");
+                Window w = readWindowSpecification();
+                if (!currentSelect.addWindow(name, w)) {
+                    throw DbException.getSyntaxError(sqlCommand, index, "unique identifier");
+                }
+            } while (readIf(COMMA));
+        }
        command.setParameterList(parameters);
        currentSelect = oldSelect;
        setSQL(command, "SELECT", start);
@@ -3049,7 +3063,7 @@ public class Parser {
        }
        Window over = null;
        if (readIf("OVER")) {
-            over = readWindowSpecification();
+            over = readWindowNameOrSpecification();
            aggregate.setOverCondition(over);
            currentSelect.setWindowQuery();
        } else if (!isAggregate) {
@@ -3059,8 +3073,24 @@ public class Parser {
        }
    }

+    private Window readWindowNameOrSpecification() {
+        return isToken(OPEN_PAREN) ? readWindowSpecification() : new Window(readAliasIdentifier(), null, null, null);
+    }
+
    private Window readWindowSpecification() {
        read(OPEN_PAREN);
+        String parent = null;
+        if (currentTokenType == IDENTIFIER) {
+            String token = currentToken;
+            if (currentTokenQuoted || ( //
+                    !equalsToken(token, "PARTITION") //
+                    && !equalsToken(token, "ROWS") //
+                    && !equalsToken(token, "RANGE") //
+                    && !equalsToken(token, "GROUPS"))) {
+                parent = token;
+                read();
+            }
+        }
        ArrayList<Expression> partitionBy = null;
        if (readIf("PARTITION")) {
            read("BY");
@@ -3077,7 +3107,7 @@ public class Parser {
        }
        WindowFrame frame = readWindowFrame();
        read(CLOSE_PAREN);
-        return new Window(partitionBy, orderBy, frame);
+        return new Window(parent, partitionBy, orderBy, frame);
    }

    private WindowFrame readWindowFrame() {

--- a/h2/src/main/org/h2/command/dml/Select.java
+++ b/h2/src/main/org/h2/command/dml/Select.java
@@ -8,6 +8,7 @@ package org.h2.command.dml;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.BitSet;
+import java.util.HashMap;
 import java.util.HashSet;
 import org.h2.api.ErrorCode;
 import org.h2.api.Trigger;
@@ -25,6 +26,7 @@ import org.h2.expression.ExpressionVisitor;
 import org.h2.expression.Parameter;
 import org.h2.expression.Wildcard;
 import org.h2.expression.aggregate.Aggregate;
+import org.h2.expression.aggregate.Window;
 import org.h2.index.Cursor;
 import org.h2.index.Index;
 import org.h2.index.IndexType;
@@ -116,6 +118,8 @@ public class Select extends Query {

    private boolean isGroupWindowStage2;

+    private HashMap<String, Window> windows;
+
    public Select(Session session) {
        super(session);
    }
@@ -214,6 +218,30 @@ public class Select extends Query {
        return distinct || distinctExpressions != null;
    }

+    /**
+     * Adds a named window definition.
+     *
+     * @param name name
+     * @param window window definition
+     * @return true if a new definition was added, false if old definition was replaced
+     */
+    public boolean addWindow(String name, Window window) {
+        if (windows == null) {
+            windows = new HashMap<>();
+        }
+        return windows.put(name, window) == null;
+    }
+
+    /**
+     * Returns a window with specified name, or null.
+     *
+     * @param name name of the window
+     * @return the window with specified name, or null
+     */
+    public Window getWindow(String name) {
+        return windows != null ? windows.get(name) : null;
+    }
+
    /**
     * Add a condition to the list of conditions.
     *

--- a/h2/src/main/org/h2/expression/aggregate/Window.java
+++ b/h2/src/main/org/h2/expression/aggregate/Window.java
@@ -7,9 +7,11 @@ package org.h2.expression.aggregate;

 import java.util.ArrayList;

+import org.h2.api.ErrorCode;
 import org.h2.command.dml.SelectOrderBy;
 import org.h2.engine.Session;
 import org.h2.expression.Expression;
+import org.h2.message.DbException;
 import org.h2.result.SortOrder;
 import org.h2.table.ColumnResolver;
 import org.h2.table.TableFilter;
@@ -22,11 +24,13 @@ import org.h2.value.ValueArray;
 */
 public final class Window {

-    private final ArrayList<Expression> partitionBy;
+    private ArrayList<Expression> partitionBy;

-    private final ArrayList<SelectOrderBy> orderBy;
+    private ArrayList<SelectOrderBy> orderBy;

-    private final WindowFrame frame;
+    private WindowFrame frame;
+
+    private String parent;

    /**
     * @param builder
@@ -54,6 +58,8 @@ public final class Window {
    /**
     * Creates a new instance of window clause.
     *
+     * @param parent
+     *            name of the parent window
     * @param partitionBy
     *            PARTITION BY clause, or null
     * @param orderBy
@@ -61,7 +67,9 @@ public final class Window {
     * @param frame
     *            window frame clause
     */
-    public Window(ArrayList<Expression> partitionBy, ArrayList<SelectOrderBy> orderBy, WindowFrame frame) {
+    public Window(String parent, ArrayList<Expression> partitionBy, ArrayList<SelectOrderBy> orderBy,
+            WindowFrame frame) {
+        this.parent = parent;
        this.partitionBy = partitionBy;
        this.orderBy = orderBy;
        this.frame = frame;
@@ -77,6 +85,7 @@ public final class Window {
     * @see Expression#mapColumns(ColumnResolver, int)
     */
    public void mapColumns(ColumnResolver resolver, int level) {
+        resolveWindows(resolver);
        if (partitionBy != null) {
            for (Expression e : partitionBy) {
                e.mapColumns(resolver, level);
@@ -89,6 +98,26 @@ public final class Window {
        }
    }

+    private void resolveWindows(ColumnResolver resolver) {
+        if (parent != null) {
+            Window p = resolver.getSelect().getWindow(parent);
+            if (p == null) {
+                throw DbException.get(ErrorCode.WINDOW_NOT_FOUND_1, parent);
+            }
+            p.resolveWindows(resolver);
+            if (partitionBy == null) {
+                partitionBy = p.partitionBy;
+            }
+            if (orderBy == null) {
+                orderBy = p.orderBy;
+            }
+            if (frame == null) {
+                frame = p.frame;
+            }
+            parent = null;
+        }
+    }
+
    /**
     * Try to optimize the window conditions.
     *

--- a/h2/src/main/org/h2/jdbc/JdbcDatabaseMetaData.java
+++ b/h2/src/main/org/h2/jdbc/JdbcDatabaseMetaData.java
@@ -1549,7 +1549,7 @@ public class JdbcDatabaseMetaData extends TraceObject implements
     * HAVING, INNER, INTERSECT, INTERSECTS, IS, JOIN, LIKE, LIMIT, LOCALTIME,
     * LOCALTIMESTAMP, MINUS, NATURAL, NOT, NULL, OFFSET, ON, ORDER, PRIMARY, ROWNUM,
     * SELECT, SYSDATE, SYSTIME, SYSTIMESTAMP, TODAY, TOP, TRUE, UNION, UNIQUE, WHERE,
-     * WITH
+     * WINDOW, WITH
     * </pre>
     *
     * @return a list of additional the keywords

--- a/h2/src/main/org/h2/message/DbException.java
+++ b/h2/src/main/org/h2/message/DbException.java
@@ -562,6 +562,7 @@ public class DbException extends RuntimeException {
        case CANNOT_MIX_INDEXED_AND_UNINDEXED_PARAMS:
        case TRANSACTION_NOT_FOUND_1:
        case AGGREGATE_NOT_FOUND_1:
+        case WINDOW_NOT_FOUND_1:
        case CAN_ONLY_ASSIGN_TO_VARIABLE_1:
        case PUBLIC_STATIC_JAVA_METHOD_NOT_FOUND_1:
        case JAVA_OBJECT_SERIALIZER_CHANGE_WITH_DATA_TABLE:

--- a/h2/src/main/org/h2/res/_messages_cs.prop
+++ b/h2/src/main/org/h2/res/_messages_cs.prop
@@ -166,7 +166,7 @@
 90133=Nelze změnit nastavení {0}, pokud je již databáze otevřena
 90134=Přístup ke třídě {0} byl odepřen
 90135=Databáze je spuštěna ve vyhrazeném režimu; nelze otevřít další spojení
-90136=Nepodporovaná podmínka vnějšího spojení: {0}
+90136=#Window not found: {0}
 90137=Lze přiřadit pouze proměnné, nikoli: {0}
 90138=Neplatný název databáze: {0}
 90139=Nenalezena veřejná statická Java metoda: {0}

--- a/h2/src/main/org/h2/res/_messages_de.prop
+++ b/h2/src/main/org/h2/res/_messages_de.prop
@@ -166,7 +166,7 @@
 90133=Kann das Setting {0} nicht ändern wenn die Datenbank bereits geöffnet ist
 90134=Der Zugriff auf die Klasse {0} ist nicht erlaubt
 90135=Die Datenbank befindet sich im Exclusiv Modus; es können keine zusätzlichen Verbindungen geöffnet werden
-90136=Diese Outer Join Bedingung wird nicht unterstützt: {0}
+90136=#Window not found: {0}
 90137=Werte können nur einer Variablen zugewiesen werden, nicht an: {0}
 90138=Ungültiger Datenbank Name: {0}
 90139=Die (public static) Java Funktion wurde nicht gefunden: {0}

--- a/h2/src/main/org/h2/res/_messages_en.prop
+++ b/h2/src/main/org/h2/res/_messages_en.prop
@@ -166,7 +166,7 @@
 90133=Cannot change the setting {0} when the database is already open
 90134=Access to the class {0} is denied
 90135=The database is open in exclusive mode; can not open additional connections
-90136=Unsupported outer join condition: {0}
+90136=Window not found: {0}
 90137=Can only assign to a variable, not to: {0}
 90138=Invalid database name: {0}
 90139=The public static Java method was not found: {0}

--- a/h2/src/main/org/h2/res/_messages_es.prop
+++ b/h2/src/main/org/h2/res/_messages_es.prop
@@ -166,7 +166,7 @@
 90133=No puede cambiar el setting {0} cuando la base de datos esta abierta
 90134=Acceso denegado a la clase {0}
 90135=La base de datos esta abierta en modo EXCLUSIVO; no puede abrir conexiones adicionales
-90136=Condición No soportada en Outer join : {0}
+90136=#Window not found: {0}
 90137=Solo puede asignarse a una variable, no a: {0}
 90138=Nombre de base de datos Invalido: {0}
 90139=El metodo Java (publico y estatico) : {0} no fue encontrado

--- a/h2/src/main/org/h2/res/_messages_fr.prop
+++ b/h2/src/main/org/h2/res/_messages_fr.prop
@@ -166,7 +166,7 @@
 90133=Impossible de changer le paramétrage {0} lorsque la base de données est déjà ouverte
 90134=L''accès à la classe {0} est interdit
 90135=La base de données est ouverte en mode exclusif; impossible d''ouvrir des connexions additionnelles
-90136=Condition de jointure extérieure non prise en charge: {0}
+90136=#Window not found: {0}
 90137=Peut seulement être assigné à une variable, pas à: {0}
 90138=Nom de la base de données invalide: {0}
 90139=La méthode Java public static n''a pas été trouvée: {0}

--- a/h2/src/main/org/h2/res/_messages_ja.prop
+++ b/h2/src/main/org/h2/res/_messages_ja.prop
@@ -166,7 +166,7 @@
 90133=データベースオープン中には、設定 {0} を変更できません
 90134=クラス {0} へのアクセスが拒否されました
 90135=データベースは排他モードでオープンされています; 接続を追加することはできません
-90136=未サポートの外部結合条件: {0}
+90136=#Window not found: {0}
 90137=割り当ては変数にのみ可能です。{0} にはできません
 90138=不正なデータベース名: {0}
 90139=public staticであるJavaメソッドが見つかりません: {0}

--- a/h2/src/main/org/h2/res/_messages_pl.prop
+++ b/h2/src/main/org/h2/res/_messages_pl.prop
@@ -166,7 +166,7 @@
 90133=Nie można zmienić ustawienia {0} gdy baza danych jest otwarta
 90134=Dostęp do klasy {0} jest zabroniony
 90135=Baza danych jest otwarta w trybie wyłączności, nie można otworzyć dodatkowych połączeń
-90136=Nieobsługiwany warunek złączenia zewnętrznego: {0}
+90136=#Window not found: {0}
 90137=Można przypisywać tylko do zmiennych, nie do: {0}
 90138=Nieprawidłowa nazwa bazy danych: {0}
 90139=Publiczna, statyczna metoda Java nie znaleziona: {0}

--- a/h2/src/main/org/h2/res/_messages_pt_br.prop
+++ b/h2/src/main/org/h2/res/_messages_pt_br.prop
@@ -166,7 +166,7 @@
 90133=#Cannot change the setting {0} when the database is already open
 90134=#Access to the class {0} is denied
 90135=#The database is open in exclusive mode; can not open additional connections
-90136=#Unsupported outer join condition: {0}
+90136=#Window not found: {0}
 90137=#Can only assign to a variable, not to: {0}
 90138=#Invalid database name: {0}
 90139=#The public static Java method was not found: {0}

--- a/h2/src/main/org/h2/res/_messages_ru.prop
+++ b/h2/src/main/org/h2/res/_messages_ru.prop
@@ -166,7 +166,7 @@
 90133=Невозможно изменить опцию {0}, когда база данных уже открыта
 90134=Доступ к классу {0} запрещен
 90135=База данных открыта в эксклюзивном режиме, открыть дополнительные соединения невозможно
-90136=Данное условие не поддерживается в OUTER JOIN : {0}
+90136=Окно не найдено: {0}
 90137=Присваивать значения возможно только переменным, но не: {0}
 90138=Недопустимое имя базы данных: {0}
 90139=public static Java метод не найден: {0}

--- a/h2/src/main/org/h2/res/_messages_sk.prop
+++ b/h2/src/main/org/h2/res/_messages_sk.prop
@@ -166,7 +166,7 @@
 90133=Nemôžem zmeniť nastavenie {0} keď už je databáza otvorená
 90134=Prístup k triede {0} odoprený
 90135=Databáza je otvorená vo výhradnom (exclusive) móde; nemôžem na ňu otvoriť ďalšie pripojenia
-90136=Nepodporovaná "outer join" podmienka: {0}
+90136=#Window not found: {0}
 90137=Môžete priradiť len do premennej, nie do: {0}
 90138=Nesprávne meno databázy: {0}
 90139=Verejná statická Java metóda nebola nájdená: {0}

--- a/h2/src/main/org/h2/res/_messages_zh_cn.prop
+++ b/h2/src/main/org/h2/res/_messages_zh_cn.prop
@@ -166,7 +166,7 @@
 90133=数据库有已启动的时候不允许更改设置{0}
 90134=访问 {0}类时被拒绝
 90135=数据库运行在独占模式(exclusive mode); 不能打开额外的连接
-90136=不支持的外连接条件: {0}
+90136=#Window not found: {0}
 90137=只能赋值到一个变量,而不是: {0}
 90138=无效数据库名称: {0}
 90139=找不到公用Java静态方法: {0}

--- a/h2/src/main/org/h2/util/ParserUtil.java
+++ b/h2/src/main/org/h2/util/ParserUtil.java
@@ -207,10 +207,15 @@ public class ParserUtil {
     */
    public static final int WHERE = UNIQUE + 1;

+    /**
+     * The token "WINDOW".
+     */
+    public static final int WINDOW = WHERE + 1;
+
    /**
     * The token "WITH".
     */
-    public static final int WITH = WHERE + 1;
+    public static final int WITH = WINDOW + 1;

    private static final int UPPER_OR_OTHER_LETTER =
            1 << Character.UPPERCASE_LETTER
@@ -426,10 +431,12 @@ public class ParserUtil {
            }
            return IDENTIFIER;
        case 'W':
-            if ("WITH".equals(s)) {
-                return WITH;
-            } else if ("WHERE".equals(s)) {
+            if ("WHERE".equals(s)) {
                return WHERE;
+            } else if ("WINDOW".equals(s)) {
+                return WINDOW;
+            } else if ("WITH".equals(s)) {
+                return WITH;
            }
            return IDENTIFIER;
        default:

--- a/h2/src/test/org/h2/test/scripts/TestScript.java
+++ b/h2/src/test/org/h2/test/scripts/TestScript.java
@@ -110,6 +110,7 @@ public class TestScript extends TestDb {
        testScript("altertable-fk.sql");
        testScript("default-and-on_update.sql");
        testScript("query-optimisations.sql");
+        testScript("window.sql");
        String decimal2;
        if (SysProperties.BIG_DECIMAL_IS_DECIMAL) {
            decimal2 = "decimal_decimal";

--- a/h2/src/test/org/h2/test/scripts/window.sql
+++ b/h2/src/test/org/h2/test/scripts/window.sql
+-- 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
+--
+
+CREATE TABLE TEST(ID INT, R INT, CATEGORY INT);
+> ok
+
+INSERT INTO TEST VALUES
+    (1, 4, 1),
+    (2, 3, 1),
+    (3, 2, 2),
+    (4, 1, 2);
+> update count: 4
+
+SELECT *, ROW_NUMBER() OVER W FROM TEST;
+> exception WINDOW_NOT_FOUND_1
+
+SELECT * FROM TEST WINDOW W AS W1, W1 AS ();
+> exception SYNTAX_ERROR_2
+
+SELECT *, ROW_NUMBER() OVER W1, ROW_NUMBER() OVER W2 FROM TEST
+    WINDOW W1 AS (W2 ORDER BY ID), W2 AS (PARTITION BY CATEGORY ORDER BY ID DESC);
+> ID R CATEGORY ROW_NUMBER() OVER (PARTITION BY CATEGORY ORDER BY ID) ROW_NUMBER() OVER (PARTITION BY CATEGORY ORDER BY ID DESC)
+> -- - -------- ----------------------------------------------------- ----------------------------------------------------------
+> 1  4 1        1                                                     2
+> 2  3 1        2                                                     1
+> 3  2 2        1                                                     2
+> 4  1 2        2                                                     1
+> rows (ordered): 4
+
+SELECT *, LAST_VALUE(ID) OVER W FROM TEST
+    WINDOW W AS (PARTITION BY CATEGORY ORDER BY ID RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING EXCLUDE CURRENT ROW);
+> ID R CATEGORY LAST_VALUE(ID) OVER (PARTITION BY CATEGORY ORDER BY ID RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING EXCLUDE CURRENT ROW)
+> -- - -------- -------------------------------------------------------------------------------------------------------------------------------------
+> 1  4 1        2
+> 2  3 1        1
+> 3  2 2        4
+> 4  1 2        3
+> rows (ordered): 4
+
+DROP TABLE TEST;
+> ok