--union

Stack two or more tabular files into one output table, reconciling differing schemas, and print the result to stdout.

octa --union FILE --union-file FILE2 [--union-file FILE3 ...] \
     [--union-drop COL]... [--union-cast COL=TYPE]... [-f tsv|json|csv]

The positional FILE plus every --union-file value form the input list (at least two files total).

How it works

The result has the union of all input columns. Columns missing from a file are filled with empty cells for its rows. Mixed numeric types widen to a common number type; otherwise the column falls back to text.

• --union-drop COL omits a column from the output (repeatable).
• --union-cast COL=TYPE overrides a column's target Arrow type, e.g. --union-cast amount=Float64 (repeatable).

Examples

octa --union jan.csv --union-file feb.csv --union-file mar.csv -f csv > q1.csv
octa --union a.parquet --union-file b.parquet --union-drop notes

See also

• --join: match rows on a key instead of stacking them.
• Union Tables (GUI) and the union_tables MCP tool.