fix

Author: JingsongLi

paimon-common/src/main/java/org/apache/paimon/data/BinaryString.java

@@ -1013,6 +1013,14 @@ public static String defaultDecodeUTF8(byte[] bytes, int offset, int len) {
         return new String(bytes, offset, len, StandardCharsets.UTF_8);
     }
 
+    /**
+     * Concatenates input strings together into a single string. Returns NULL if any argument is
+     * NULL.
+     */
+    public static BinaryString concat(BinaryString... inputs) {
+        return concat(Arrays.asList(inputs));
+    }
+
     /**
      * Concatenates input strings together into a single string. Returns NULL if any argument is
      * NULL.
@@ -1042,6 +1050,17 @@ public static BinaryString concat(Iterable<BinaryString> inputs) {
         return fromBytes(result);
     }
 
+    /**
+     * Concatenates input strings together into a single string using the separator. Returns NULL If
+     * the separator is NULL.
+     *
+     * <p>Note: CONCAT_WS() does not skip any empty strings, however it does skip any NULL values
+     * after the separator. For example, concat_ws(",", "a", null, "c") would yield "a,c".
+     */
+    public static BinaryString concatWs(BinaryString separator, BinaryString... inputs) {
+        return concatWs(separator, Arrays.asList(inputs));
+    }
+
     /**
      * Concatenates input strings together into a single string using the separator. Returns NULL If
      * the separator is NULL.

paimon-common/src/test/java/org/apache/paimon/data/BinaryStringTest.java

@@ -35,6 +35,8 @@
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.apache.paimon.data.BinaryString.EMPTY_UTF8;
 import static org.apache.paimon.data.BinaryString.blankString;
+import static org.apache.paimon.data.BinaryString.concat;
+import static org.apache.paimon.data.BinaryString.concatWs;
 import static org.apache.paimon.data.BinaryString.fromBytes;
 import static org.apache.paimon.utils.DecimalUtils.castFrom;
 import static org.assertj.core.api.Assertions.assertThat;
@@ -221,6 +223,42 @@ public void testMultiSegments() {
         assertThat(binaryString2.compareTo(binaryString1)).isEqualTo(1);
     }
 
+    @TestTemplate
+    void concatTest() {
+        assertThat(concat()).isEqualTo(EMPTY_UTF8);
+        assertThat(concat((BinaryString) null)).isNull();
+        assertThat(concat(EMPTY_UTF8)).isEqualTo(EMPTY_UTF8);
+        assertThat(concat(fromString("ab"))).isEqualTo(fromString("ab"));
+        assertThat(concat(fromString("a"), fromString("b"))).isEqualTo(fromString("ab"));
+        assertThat(concat(fromString("a"), fromString("b"), fromString("c")))
+                .isEqualTo(fromString("abc"));
+        assertThat(concat(fromString("a"), null, fromString("c"))).isNull();
+        assertThat(concat(fromString("a"), null, null)).isNull();
+        assertThat(concat(null, null, null)).isNull();
+        assertThat(concat(fromString("数据"), fromString("砖头"))).isEqualTo(fromString("数据砖头"));
+    }
+
+    @TestTemplate
+    void concatWsTest() {
+        // Returns empty if the separator is null
+        assertThat(concatWs(null, (BinaryString) null)).isNull();
+        assertThat(concatWs(null, fromString("a"))).isNull();
+
+        // If separator is null, concatWs should skip all null inputs and never return null.
+        BinaryString sep = fromString("哈哈");
+        assertThat(concatWs(sep, EMPTY_UTF8)).isEqualTo(EMPTY_UTF8);
+        assertThat(concatWs(sep, fromString("ab"))).isEqualTo(fromString("ab"));
+        assertThat(concatWs(sep, fromString("a"), fromString("b"))).isEqualTo(fromString("a哈哈b"));
+        assertThat(concatWs(sep, fromString("a"), fromString("b"), fromString("c")))
+                .isEqualTo(fromString("a哈哈b哈哈c"));
+        assertThat(concatWs(sep, fromString("a"), null, fromString("c")))
+                .isEqualTo(fromString("a哈哈c"));
+        assertThat(concatWs(sep, fromString("a"), null, null)).isEqualTo(fromString("a"));
+        assertThat(concatWs(sep, null, null, null)).isEqualTo(EMPTY_UTF8);
+        assertThat(concatWs(sep, fromString("数据"), fromString("砖头")))
+                .isEqualTo(fromString("数据哈哈砖头"));
+    }
+
     @TestTemplate
     public void contains() {
         assertThat(EMPTY_UTF8.contains(EMPTY_UTF8)).isTrue();