Format of STRUCT is ambiguous

[apstndb]

Currently, spanner-cli formats of STRUCT values as [...].
I think it is ambiguous with format of ARRAY values.
(We know nested ARRAY and top-level STRUCT is forbid so strictly ambiguous.)

$ spanner-cli -e 'SELECT ARRAY(SELECT AS STRUCT 1, 2)'
[[1, 2]]

$ spanner-cli -e 'SELECT SAMPLE_LOCK_REQUESTS FROM SPANNER_SYS.LOCK_STATS_TOP_HOUR' -t
...
[[tbl._exists, Exclusive], [tbl._exists, Exclusive], [tbl._exists, Exclusive], [tbl._exists, Exclusive]]
...

How about does STRUCT use (...) like native notation?

[yfuruyama]

It makes sense, but at the same time it is important to have a consistency with gcloud and Cloud Console.

For example, this is the result of gcloud spanner databases execute-sql.

$ gcloud spanner databases execute-sql --instance=${INSTANCE} --sql="SELECT ARRAY(SELECT AS STRUCT 1, 2);" ${DB}
(Unspecified)
[['1', '2']]

And this is the result by Cloud Console.

[apstndb]

Yeah, it seems there are only bad precedents.
In BigQuery, STRUCT(record) values are expanded and FORMAT("%T", ARRAY(SELECT AS STRUCT 1, 2)) prints [(1, 2)] but it isn't yet be supported in Cloud Spanner.

[yfuruyama]

Yeah BigQuery's support for STRUCT data type is mature as it supports STRUCT data type for table schema and top-level query result.

How about discussing this again once we hear another user's voice or STRUCT data type gets frequently used in Cloud Spanner?

[apstndb]

This issue was originally intended to address the difficulty in interpreting [] as representing STRUCT. However, its priority has decreased since it is now possible to confirm that it is of the STRUCT type through the following reference:

• Print result type information inspired by DuckDB DESCRIBE #190