Added the simple Oracle function ORA_HASH (+ tests) to make H2 more Oracle complaint.

To see what it does see http://docs.oracle.com/cd/B12037_01/server.101/b10759/functions097.htm

h2/src/main/org/h2/expression/Function.java

@@ -92,7 +92,7 @@ public class Function extends Expression implements FunctionCall {
             STRINGDECODE = 80, STRINGTOUTF8 = 81, UTF8TOSTRING = 82,
             XMLATTR = 83, XMLNODE = 84, XMLCOMMENT = 85, XMLCDATA = 86,
             XMLSTARTDOC = 87, XMLTEXT = 88, REGEXP_REPLACE = 89, RPAD = 90,
-            LPAD = 91, CONCAT_WS = 92, TO_CHAR = 93, TRANSLATE = 94;
+            LPAD = 91, CONCAT_WS = 92, TO_CHAR = 93, TRANSLATE = 94, ORA_HASH = 95;
 
     public static final int CURDATE = 100, CURTIME = 101, DATE_ADD = 102,
             DATE_DIFF = 103, DAY_NAME = 104, DAY_OF_MONTH = 105,
@@ -297,6 +297,7 @@ public class Function extends Expression implements FunctionCall {
         addFunction("RPAD", RPAD, VAR_ARGS, Value.STRING);
         addFunction("LPAD", LPAD, VAR_ARGS, Value.STRING);
         addFunction("TO_CHAR", TO_CHAR, VAR_ARGS, Value.STRING);
+        addFunction("ORA_HASH", ORA_HASH, VAR_ARGS, Value.INT);
         addFunction("TRANSLATE", TRANSLATE, 3, Value.STRING);
 
         // date
@@ -1394,6 +1395,11 @@ public class Function extends Expression implements FunctionCall {
                     v1.getInt(), v2 == null ? null : v2.getString(), false),
                     database.getMode().treatEmptyStringsAsNull);
             break;
+        case ORA_HASH:
+            result = ValueLong.get(oraHash(v0.getString(),
+                    v1 == null ? null : v1.getInt(),
+                    v2 == null ? null : v2.getInt()));
+            break;
         case TO_CHAR:
             switch(v0.getType()){
             case Value.TIME:
@@ -2039,6 +2045,20 @@ public class Function extends Expression implements FunctionCall {
         return new String(chars);
     }
 
+    private static Integer oraHash(String s, Integer bucket, Integer seed) {
+        int hc = s.hashCode();
+        if (seed != null && seed.intValue() != 0) {
+            hc *= seed.intValue() * 17;
+        }
+        if (bucket == null  || bucket.intValue() <= 0) {
+            // do nothing
+        } else {
+            hc %= bucket.intValue();
+        }
+        return hc;
+    }
+
+    
     @Override
     public int getType() {
         return dataType;
@@ -2088,6 +2108,10 @@ public class Function extends Expression implements FunctionCall {
             min = 1;
             max = 3;
             break;
+        case ORA_HASH:
+            min = 1;
+            max = 3;
+            break;
         case REPLACE:
         case LOCATE:
         case INSTR:

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

@@ -90,6 +90,7 @@ public class TestFunctions extends TestBase implements AggregateFunction {
         testNvl2();
         testConcatWs();
         testTruncate();
+        testOraHash();
         testToCharFromDateTime();
         testToCharFromNumber();
         testToCharFromText();
@@ -1221,6 +1222,18 @@ public class TestFunctions extends TestBase implements AggregateFunction {
         conn.close();
     }
 
+    private void testOraHash() throws SQLException {
+        deleteDb("functions");
+        Connection conn = getConnection("functions");
+        Statement stat = conn.createStatement();
+        String testStr = "foo";
+        assertResult(String.valueOf("foo".hashCode()), stat, String.format("SELECT ORA_HASH('%s') FROM DUAL", testStr));
+        assertResult(String.valueOf("foo".hashCode()), stat,
+                String.format("SELECT ORA_HASH('%s', 0) FROM DUAL", testStr));
+        assertResult(String.valueOf("foo".hashCode()), stat,
+                String.format("SELECT ORA_HASH('%s', 0, 0) FROM DUAL", testStr));
+    }
+
     private void testToCharFromDateTime() throws SQLException {
         deleteDb("functions");
         Connection conn = getConnection("functions");
@@ -1658,7 +1671,6 @@ public class TestFunctions extends TestBase implements AggregateFunction {
         conn.close();
     }
 
-
     private void testGenerateSeries() throws SQLException {
         Connection conn = getConnection("functions");
         Statement stat = conn.createStatement();