Null when the column does not hold JSON objects; an empty list when it does but nothing is nameable.
Only keys that RECUR are named: a record repeats its keys, a map keyed by data does not, so
{"ZZALICE":3}, {"ZZBOB":7} yields no stable key and the usernames never reach the prompt. Known
residual: a fixed set of identifier-shaped keys present on most rows still reads as a record.
Null when the column does not hold JSON objects; an empty list when it does but nothing is nameable. Only keys that RECUR are named: a record repeats its keys, a map keyed by data does not, so
{"ZZALICE":3}, {"ZZBOB":7}yields no stable key and the usernames never reach the prompt. Known residual: a fixed set of identifier-shaped keys present on most rows still reads as a record.