Directly Read DuckDB Databases

DuckDB allows directly reading DuckDB files through the read_duckdb function:

read_duckdb(⟨'path_to_database'⟩, table_name = ⟨'table_to_read'⟩);

Using this function is equivalent to performing the following steps:

Attaching to the database using a read-only connection.
Querying the table specified through the table_name argument.
Closing the connection to the database database.

Examples

Reading a Specific Table

To read the region table from the TPC-H dataset, run:

SELECT r_regionkey, r_name
FROM read_duckdb('https://blobs.duckdb.org/data/tpch-sf10.db', table_name = 'region');

┌─────────────┬─────────────┐
│ r_regionkey │   r_name    │
│    int32    │   varchar   │
├─────────────┼─────────────┤
│           0 │ AFRICA      │
│           1 │ AMERICA     │
│           2 │ ASIA        │
│           3 │ EUROPE      │
│           4 │ MIDDLE EAST │
└─────────────┴─────────────┘

Reading from Multiple Databases

You can use globbing to read from multiple databases. Two illustrate this, let’s create two tables:

duckdb my-1.duckdb \
    -c "CREATE TABLE numbers AS SELECT 42 AS x;" \
    -c "CREATE TABLE letters AS SELECT 'm' AS a;"

duckdb my-2.duckdb \
    -c "CREATE TABLE numbers AS SELECT 43 AS x;"

Then, in DuckDB, you can run:

SELECT x FROM read_duckdb('my-*.duckdb', table_name = 'numbers');

┌───────┐
│   x   │
│ int32 │
├───────┤
│    42 │
│    43 │
└───────┘

Reading from Databases with a Single Table

If all databases in read_duckdb’s argument have a single table, the table_name argument is optional:

FROM read_duckdb('my-2.duckdb');

┌───────┐
│   x   │
│ int32 │
├───────┤
│     3 │
└───────┘

If the extension is .db or .duckdb, you can also omit the read_duckdb call (similarly to how you can omit read_csv and read_parquet):

FROM 'my-2.duckdb';

Limitations

read_duckdb currently only supports reading from tables. Reading from views is not yet supported.