The DuckDB Julia package provides a high-performance front-end for DuckDB. Much like SQLite, DuckDB runs in-process within the Julia client, and provides a DBInterface front-end.

The package also supports multi-threaded execution. It uses Julia threads/tasks for this purpose. If you wish to run queries in parallel, you must launch Julia with multi-threading support (by e.g., setting the JULIA_NUM_THREADS environment variable).

Installation

Install DuckDB as follows:

using Pkg
Pkg.add("DuckDB")

Alternatively:

pkg> add DuckDB

Basics

using DuckDB

# create a new in-memory database
con = DBInterface.connect(DuckDB.DB, ":memory:")

# create a table
DBInterface.execute(con, "CREATE TABLE integers (i INTEGER)")

# insert data using a prepared statement
stmt = DBInterface.prepare(con, "INSERT INTO integers VALUES(?)")
DBInterface.execute(stmt, [42])

# query the database
results = DBInterface.execute(con, "SELECT 42 a")
print(results)

Scanning DataFrames

The DuckDB Julia package also provides support for querying Julia DataFrames. Note that the DataFrames are directly read by DuckDB - they are not inserted or copied into the database itself.

If you wish to load data from a DataFrame into a DuckDB table you can run a CREATE TABLE ... AS or INSERT INTO query.

using DuckDB
using DataFrames

# create a new in-memory dabase
con = DBInterface.connect(DuckDB.DB)

# create a DataFrame
df = DataFrame(a = [1, 2, 3], b = [42, 84, 42])

# register it as a view in the database
DuckDB.register_data_frame(con, df, "my_df")

# run a SQL query over the DataFrame
results = DBInterface.execute(con, "SELECT * FROM my_df")
print(results)

Original Julia Connector

Credits to kimmolinna for the original DuckDB Julia connector.