Add UUID support to DuckDBAppender (fixes #313)

src/main/java/org/duckdb/DuckDBAppender.java

@@ -52,6 +52,7 @@ public class DuckDBAppender implements AutoCloseable {
 
         supportedTypes.add(DUCKDB_TYPE_ARRAY.typeId);
         supportedTypes.add(DUCKDB_TYPE_STRUCT.typeId);
+        supportedTypes.add(DUCKDB_TYPE_UUID.typeId);
     }
     private static final CAPIType[] int8Types = new CAPIType[] {DUCKDB_TYPE_TINYINT, DUCKDB_TYPE_UTINYINT};
     private static final CAPIType[] int16Types = new CAPIType[] {DUCKDB_TYPE_SMALLINT, DUCKDB_TYPE_USMALLINT};
@@ -922,6 +923,26 @@ public DuckDBAppender append(String value) throws SQLException {
         return appendStringOrBlobInternal(DUCKDB_TYPE_VARCHAR, bytes);
     }
 
+    public DuckDBAppender appendUUID(long mostSigBits, long leastSigBits) throws SQLException {
+        Column col = currentColumnWithRowPos(DUCKDB_TYPE_UUID);
+        col.data.putLong(leastSigBits);
+        mostSigBits ^= Long.MIN_VALUE;
+        col.data.putLong(mostSigBits);
+        incrementColOrStructFieldIdx();
+        return this;
+    }
+
+    public DuckDBAppender append(UUID value) throws SQLException {
+        checkCurrentColumnType(DUCKDB_TYPE_UUID);
+        if (value == null) {
+            return appendNull();
+        }
+
+        long mostSigBits = value.getMostSignificantBits();
+        long leastSigBits = value.getLeastSignificantBits();
+        return appendUUID(mostSigBits, leastSigBits);
+    }
+
     public DuckDBAppender appendEpochDays(int days) throws SQLException {
         Column col = currentColumnWithRowPos(DUCKDB_TYPE_DATE);
         col.data.putInt(days);

src/main/java/org/duckdb/DuckDBBindings.java

@@ -171,7 +171,7 @@ enum CAPIType {
         // duckdb_array, only useful as logical type
         DUCKDB_TYPE_ARRAY(33, 0),
         // duckdb_hugeint
-        DUCKDB_TYPE_UUID(27),
+        DUCKDB_TYPE_UUID(27, 16),
         // union type, only useful as logical type
         DUCKDB_TYPE_UNION(28),
         // duckdb_bit

src/test/java/org/duckdb/TestAppender.java

@@ -139,6 +139,32 @@ public static void test_appender_unsigned() throws Exception {
         }
     }
 
+    public static void test_appender_uuid() throws Exception {
+        try (DuckDBConnection conn = DriverManager.getConnection(JDBC_URL).unwrap(DuckDBConnection.class);
+             Statement stmt = conn.createStatement()) {
+
+            stmt.execute("CREATE TABLE tab1(col1 INT, col2 UUID)");
+            UUID uuid1 = UUID.randomUUID();
+            UUID uuid2 = UUID.randomUUID();
+            try (DuckDBAppender appender = conn.createAppender("tab1")) {
+                appender.beginRow().append(1).append(uuid1).endRow();
+                appender.beginRow().append(2).append(uuid2).endRow();
+                appender.flush();
+            }
+
+            try (DuckDBResultSet rs =
+                     stmt.executeQuery("SELECT * FROM tab1 ORDER BY col1").unwrap(DuckDBResultSet.class)) {
+                assertTrue(rs.next());
+                assertEquals(rs.getUuid(2), uuid1);
+                assertEquals(rs.getObject(2, UUID.class), uuid1);
+                assertTrue(rs.next());
+                assertEquals(rs.getUuid(2), uuid2);
+                assertEquals(rs.getObject(2, UUID.class), uuid2);
+                assertFalse(rs.next());
+            }
+        }
+    }
+
     public static void test_appender_long_string() throws Exception {
         try (DuckDBConnection conn = DriverManager.getConnection(JDBC_URL).unwrap(DuckDBConnection.class);
              Statement stmt = conn.createStatement()) {