MartijnVisser commented on code in PR #22951:
URL: https://github.com/apache/flink/pull/22951#discussion_r1489314997
##########
flink-table/flink-table-common/src/main/java/org/apache/flink/table/functions/BuiltInFunctionDefinitions.java:
##########
@@ -231,6 +232,21 @@ ANY, and(logical(LogicalTypeRoot.BOOLEAN), LITERAL)
"org.apache.flink.table.runtime.functions.scalar.ArrayContainsFunction")
.build();
+ public static final BuiltInFunctionDefinition ARRAY_SORT =
+ BuiltInFunctionDefinition.newBuilder()
+ .name("ARRAY_SORT")
+ .kind(SCALAR)
+ .inputTypeStrategy(
+ or(
+ sequence(new
ArrayComparableElementArgumentTypeStrategy()),
+ sequence(
+ new
ArrayComparableElementArgumentTypeStrategy(),
+ logical(LogicalTypeRoot.BOOLEAN))))
Review Comment:
This is quite a rabbit hole 😆
1. Databricks has two functions:
* sort_array
https://docs.databricks.com/en/sql/language-manual/functions/sort_array.html -
Sorts ascending, puts NULL at beginning.
* array_sort
https://docs.databricks.com/en/sql/language-manual/functions/array_sort.html -
Sorts ascending, puts NULL at the end.
2. Spark has
https://spark.apache.org/docs/latest/api/sql/index.html#sort_array which is
indeed not different from the Databricks one. Sorts ascending, puts NULL at
beginning
3. Snowflake indeed has
https://docs.snowflake.com/en/sql-reference/functions/array_sort - Sorts
ascending, puts NULL at the end.
4. Trino, that has `array_sort(x)` - Sorts ascending, puts NULL at the end.
5. StarRocks also has this function
https://docs.starrocks.io/docs/2.2/sql-reference/sql-functions/array-functions/array_sort/
- Sorts ascending, puts NULL at beginning
6. Doris has it
https://doris.apache.org/docs/1.2/sql-manual/sql-functions/array-functions/array_sort/
- Sorts ascending, puts NULL at beginning
7. Hive uses NULLS FIRST as the default behavior in ascending ordering mode,
per https://issues.apache.org/jira/browse/HIVE-12994 - Sorts ascending, puts
NULL at beginning.
I do think that the Snowflake has the cleanest function signature: there's
just one function, and it has two optional arguments to give all the
flexibility.
I think the default sorting mode should be ascending, and then it boils down
to decide on the default location on where to put NULL. Out of the 7
implementations, we have 5 who put NULL at the beginning, and 2 who put them at
the end. Naturally, I think we should put NULL at the beginning but I'm +0 on
the default location of NULL.
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