Fix the result mismatch for right expression (oap-project#107)

zhejiangxiaomai · Mar 27, 2023 · 8b6ba5a · 8b6ba5a
1 parent a490c77
commit 8b6ba5a
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/velox/functions/prestosql/StringFunctions.h b/velox/functions/prestosql/StringFunctions.h
@@ -349,6 +349,13 @@ struct SubstrFunction {
     if (start < 0) {
       start = numCharacters + start + 1;
     }
+
+    // Following vanilla spark semantics. When the start is 0 after adjusing start,
+    // Keep the origin input. 
+    if (start <= 0) {
+      start = 1;
+      length = numCharacters;
+    }
 
     // Following Presto semantics
     if (start <= 0 || start > numCharacters || length <= 0) {