wuchong commented on a change in pull request #9394:
[FLINK-13547][table-planner-blink] Verify and correct string function's
semantic for Blink planner
URL: https://github.com/apache/flink/pull/9394#discussion_r312318835
##########
File path:
flink-table/flink-table-runtime-blink/src/main/java/org/apache/flink/table/dataformat/BinaryStringUtil.java
##########
@@ -749,21 +749,21 @@ public static BinaryString concat(Iterable<BinaryString>
inputs) {
}
/**
- * Concatenates input strings together into a single string using the
separator.
- * A null input is skipped. For example, concat(",", "a", null, "c")
would yield "a,c".
+ * <p>Concatenates input strings together into a single string using
the separator.
+ * Returns NULL If the separator is NULL.</p>
+ *
+ * <p>Note: CONCAT_WS() does not skip any empty strings, however it
does skip any NULL values after
+ * the separator. For example, concat(",", "a", null, "c") would yield
"a,c".</p>
Review comment:
```suggestion
* the separator. For example, concat_ws(",", "a", null, "c") would
yield "a,c".</p>
```
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