spantype

$ ./spantype --help
Usage of spantype:
  -mode string
        format mode (simplest|simple|normal|verbose|more) (default "verbose")
  -type-annotation string
        how to render TypeAnnotation: suffix|omit|primary (default "suffix")

$ gcloud spanner databases execute-sql ${SPANNER_DATABASE} \
    --format="json" --query-mode=PLAN \
    --sql 'SELECT 1 AS n, ARRAY(SELECT AS STRUCT 1 AS n, ARRAY(SELECT AS STRUCT 1 AS n) AS `inner`) AS `outer`' \
    | jq .metadata.rowType | ./spantype 
n INT64, outer ARRAY<STRUCT<n INT64, inner ARRAY<STRUCT<n INT64>>>>

# with --mode
$ gcloud spanner databases execute-sql ${SPANNER_DATABASE} \
    --format="json" --query-mode=PLAN \
    --sql 'SELECT 1 AS n, ARRAY(SELECT AS STRUCT 1 AS n, ARRAY(SELECT AS STRUCT 1 AS n) AS `inner`) AS `outer`' \
    | jq .metadata.rowType | ./spantype --mode=simplest
INT64, ARRAY