select

select is a schema decision. It keeps the columns you name, in the order you name them.

Use it to make the next node cheaper and clearer: trim wide source tables, prepare a report table, or define the exact payload crossing into a language node.

Projection contract

Field	Required	Notes
inputs	yes	Exactly one upstream table.
columns	yes	Array of selected columns. Runtime compiles each entry as an expression, while the schema currently restricts them to identifier-shaped strings.

Review notes

• default is the same rows with only the selected columns.
• Column order is part of the node behavior, so use select when report ordering matters.
• Selecting a nonexistent column is a hard validation error.

Example

- id: keep_cols
  kind: select
  inputs: [data]
  columns: [a, b, c]

Related

• derive - create named features before selecting them
• Expression language - projection syntax notes