To read data from a Parquet file, use the read_parquet function in the FROM clause of a query:

SELECT * FROM read_parquet('input.parquet'); 

Alternatively, you can omit the read_parquet function and let DuckDB infer it from the extension:

SELECT * FROM 'input.parquet'; 

To create a new table using the result from a query, use CREATE TABLE ... AS SELECT statement:

CREATE TABLE new_tbl AS SELECT * FROM read_parquet('input.parquet'); 

To load data into an existing table from a query, use INSERT INTO from a SELECT statement:

INSERT INTO tbl SELECT * FROM read_parquet('input.parquet'); 

Alternatively, the COPY statement can also be used to load data from a Parquet file into an existing table:

COPY tbl FROM 'input.parquet' (FORMAT parquet); 

Adjusting the Schema on the Fly

You can load a Parquet file into a slightly different schema (e.g., different number of columns, more relaxed types) using the following trick.

Suppose we have a Parquet file with two columns, c1 and c2:

COPY (FROM (VALUES (42, 43)) t(c1, c2)) TO 'f.parquet'; 

If we want to add another column c3 that is not present in the file, we can run:

FROM (VALUES(NULL::VARCHAR, NULL, NULL)) t(c1, c2, c3) WHERE false UNION ALL BY NAME FROM 'f.parquet'; 

The first FROM clause generates an empty tables with three columns where c1 is a VARCHAR. Then, we use UNION ALL BY NAME to union the Parquet file. The result here is:

┌─────────┬───────┬───────┐ │ c1 │ c2 │ c3 │ │ varchar │ int32 │ int32 │ ├─────────┼───────┼───────┤ │ 42 │ 43 │ NULL │ └─────────┴───────┴───────┘ 

For additional options, see the Parquet loading reference.