LOAD INTO

LOAD INTO sr.silver.pedidos            -- conn[.schema].table, or a quoted path
  USING stream_load                    -- load path; optional, starrocks/doris only
  UPSERT ON (empresa, num_pedido)      -- disposition (below)
  SPLIT BY (num_pedido) JOBS 4         -- key-range parallel load
  WITH (label_prefix = 'noturno')      -- overrides the connection's label_prefix
AS
<query>;

• File target by quoted path — the extension picks the writer: LOAD INTO '/out/x.csv', LOAD INTO '/out/x.parquet', LOAD INTO '/out/x.arrow' (Arrow IPC file; also .feather, .ipc, and .arrows for the stream format, local paths only), or an object-store path LOAD INTO 'az://account/container/bronze/x.parquet' or LOAD INTO 's3://bucket/bronze/x.parquet'.
• USING stream_load names the one load path StarRocks and Doris have, and may be left out; on any other target, or with another name, it is an error.
• A per-row dynamic target uses IDENTIFIER(<string-expr>) over loop vars (FOR EACH): LOAD INTO sr.IDENTIFIER('crm_' || lower($name)) .... A file target built this way must end in a literal extension, which picks the writer.
• .xlsx is read but never written: a workbook target is a plan-time error.
• UPSERT needs a table to merge into; on a file target it is a plan-time error.
• WITH (...) on a LOAD INTO takes delimiter and format (a file) and label_prefix (StarRocks, Doris); any other key is a plan-time error rather than ignored.
• Dispositions on a table target: APPEND (default, omissible) · REPLACE (overwrite) · UPSERT ON (k1, k2) · UPSERT ON (id) PARTIAL COLS (a, b) · bare UPSERT (infer the PK from the source table’s metadata at plan time — needs a table read on a SQL source that exposes it). An empty/unresolved upsert key is an error, never a silent no-op.
• Dispositions on a file target — the omissible default is not APPEND: a bare LOAD INTO 'x.csv', like REPLACE, creates or truncates the file, so a rerun replaces it. Explicit APPEND accumulates for CSV only: the file is opened without truncating and the header row is written only when it was absent or empty. Explicit APPEND is a plan-time error for .parquet and Arrow IPC (the footer indexes every row group or batch and is written last, so appending means rewriting the file), for az:// / s3:// (an object is replaced on write, never extended), and for sftp:// / smb:// (the file is written beside the target and renamed over it) — use REPLACE, a per-run path, or INTO BUFFER (HTTP mode).
• SPLIT BY (col) parallelizes the load by key ranges; JOBS n fixes the lane count (otherwise the CLI -j applies).

stdout is not syntax: a terminal SELECT ...; statement prints the result as an aligned table — basalt run -c "SELECT * FROM 'x.csv'" works as a mini-DuckDB.