yaooqinn commented on a change in pull request #26371: [SPARK-27976][SQL] Add built-in Array Functions: array_append URL: https://github.com/apache/spark/pull/26371#discussion_r341942785
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/collectionOperations.scala ########## @@ -3928,3 +3928,128 @@ case class ArrayExcept(left: Expression, right: Expression) extends ArrayBinaryL override def prettyName: String = "array_except" } + +@ExpressionDescription( + usage = """ + _FUNC_(array, element) - Returns an array of appending an element to the end of an array + """, + examples = """ + Examples: + > SELECT _FUNC_(array(1, 2, 3), 3); + [1,2,3,3] + > SELECT _FUNC_(array(1, 2, 3), null); + [1,2,3,null] + > SELECT _FUNC_(a, e) FROM VALUES (array(1,2), 3), (array(3, 4), null), (null, 3) tbl(a, e); + NULL + [1,2,3] + [3,4,null] + """, + since = "3.0.0") +case class ArrayAppend(left: Expression, right: Expression) extends BinaryExpression { Review comment: Hi @maropu , the key difference is when the array is null and the new element is not, array_append will create new array but concat's result will be null. please see the following cases. ``` -- !query 18 select array_append(a, e) from VALUES (array(1,2), 3), (array(3, 4), null), (null, 3), (null, null) tbl(a, e) -- !query 18 schema struct<array_append(a, e):array<int>> -- !query 18 output NULL [1,2,3] [3,4,null] [3] -- !query 19 select concat(a, array(e)) from VALUES (array(1,2), 3), (array(3, 4), null), (null, 3), (null, null) tbl(a, e) -- !query 19 schema struct<concat(a, array(e)):array<int>> -- !query 19 output NULL NULL [1,2,3] [3,4,null] ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org