[CALCITE-6663] Support SPLIT_PART function for PostgreSQL

zhuqi-lucas · Nov 1, 2024 · 48434f4 · 48434f4
1 parent 43973fe
commit 48434f4
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Showing 3 changed files with 263 additions and 262 deletions.
diff --git a/core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java b/core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java
@@ -917,8 +917,8 @@ public static List<String> split(String s, String delimiter) {
 
   /** SQL {@code SPLIT_PART(string, string, int)} function. */
   public static String splitPart(String s, String delimiter, int n) {
-    if (s == null || delimiter == null || delimiter.isEmpty() || n == 0) {
-      return null;
+    if (s == null || s == "" || delimiter == null || delimiter.isEmpty() || n == 0) {
+      return "";
     }
 
     String[] parts = s.split(Pattern.quote(delimiter), -1);
@@ -929,7 +929,7 @@ public static String splitPart(String s, String delimiter, int n) {
     }
 
     if (n <= 0 || n > partCount) {
-      return null;
+      return "";
     }
 
     return parts[n - 1];

diff --git a/core/src/test/java/org/apache/calcite/test/SqlFunctionsTest.java b/core/src/test/java/org/apache/calcite/test/SqlFunctionsTest.java
@@ -1061,14 +1061,14 @@ private void checkCeil(int x, int y, int result) {
 
     assertThat(SqlFunctions.splitPart("abc,,ghi", ",", 2), is(""));
     assertThat(SqlFunctions.splitPart("", ",", 1), is(""));
-    assertThat(SqlFunctions.splitPart("abc", "", 1), is(nullValue()));
+    assertThat(SqlFunctions.splitPart("abc", "", 1), is(""));
 
-    assertThat(SqlFunctions.splitPart(null, ",", 1), is(nullValue()));
-    assertThat(SqlFunctions.splitPart("abc,def", null, 1), is(nullValue()));
-    assertThat(SqlFunctions.splitPart("abc,def", ",", 0), is(nullValue()));
+    assertThat(SqlFunctions.splitPart(null, ",", 1), is(""));
+    assertThat(SqlFunctions.splitPart("abc,def", null, 1), is(""));
+    assertThat(SqlFunctions.splitPart("abc,def", ",", 0), is(""));
 
-    assertThat(SqlFunctions.splitPart("abc,def", ",", 3), is(nullValue()));
-    assertThat(SqlFunctions.splitPart("abc,def", ",", -3), is(nullValue()));
+    assertThat(SqlFunctions.splitPart("abc,def", ",", 3), is(""));
+    assertThat(SqlFunctions.splitPart("abc,def", ",", -3), is(""));
   }
 
   @Test void testByteString() {