# /// script # requires-python = ">=3.11" # dependencies = [ # "marimo", # "duckdb==1.2.1", # "pyarrow==19.0.1", # "polars[pyarrow]==1.25.2", # "pandas==2.2.3", # ] # /// import marimo __generated_with = "0.14.10" app = marimo.App(width="medium") @app.cell(hide_code=True) def _(mo): mo.md( r""" # Working with Apache Arrow *By [Thomas Liang](https://github.com/thliang01)* # """ ) return @app.cell(hide_code=True) def _(mo): mo.md( r""" [Apache Arrow](https://arrow.apache.org/) is a multi-language toolbox for building high performance applications that process and transport large data sets. It is designed to both improve the performance of analytical algorithms and the efficiency of moving data from one system or programming language to another. A critical component of Apache Arrow is its in-memory columnar format, a standardized, language-agnostic specification for representing structured, table-like datasets in-memory. This data format has a rich data type system (included nested and user-defined data types) designed to support the needs of analytic database systems, data frame libraries, and more. DuckDB has native support for Apache Arrow, which is an in-memory columnar data format. This allows for efficient data transfer between DuckDB and other Arrow-compatible systems, such as Polars and Pandas (via PyArrow). In this notebook, we'll explore how to: - Create an Arrow table from a DuckDB query. - Load an Arrow table into DuckDB. - Convert between DuckDB, Arrow, and Polars/Pandas DataFrames. - Combining data from multiple sources - Performance benefits """ ) return @app.cell def _(mo): mo.sql( """ CREATE TABLE IF NOT EXISTS users ( id INTEGER, name VARCHAR, age INTEGER, city VARCHAR ); INSERT INTO users VALUES (1, 'Alice', 30, 'New York'), (2, 'Bob', 24, 'London'), (3, 'Charlie', 35, 'Paris'), (4, 'David', 29, 'New York'), (5, 'Eve', 40, 'London'); """ ) return @app.cell(hide_code=True) def _(mo): mo.md( r""" ## 1. Creating an Arrow Table from a DuckDB Query You can directly fetch the results of a DuckDB query as an Apache Arrow table using the `.arrow()` method on the query result. """ ) return @app.cell def _(mo): users_arrow_table = mo.sql( # type: ignore """ SELECT * FROM users WHERE age > 30; """ ).to_arrow() return (users_arrow_table,) @app.cell def _(users_arrow_table): users_arrow_table return @app.cell(hide_code=True) def _(mo): mo.md(r"The `.arrow()` method returns a `pyarrow.Table` object. We can inspect its schema:") return @app.cell def _(users_arrow_table): users_arrow_table.schema return @app.cell(hide_code=True) def _(mo): mo.md( r""" ## 2. Loading an Arrow Table into DuckDB You can also register an existing Arrow table (or a Polars/Pandas DataFrame, which uses Arrow under the hood) directly with DuckDB. This allows you to query the in-memory data without any copying, which is highly efficient. """ ) return @app.cell def _(pa): # Create an Arrow table in Python new_data = pa.table({ 'id': [6, 7], 'name': ['Fiona', 'George'], 'age': [22, 45], 'city': ['Berlin', 'Tokyo'] }) return (new_data,) @app.cell(hide_code=True) def _(mo): mo.md( r""" Now, we can query this Arrow table `new_data` directly from SQL by embedding it in the query. """ ) return @app.cell def _(mo, new_data): mo.sql( f""" SELECT name, age, city FROM new_data WHERE age > 30; """ ) return @app.cell(hide_code=True) def _(mo): mo.md( r""" ## 3. Convert between DuckDB, Arrow, and Polars/Pandas DataFrames. The real power of DuckDB's Arrow integration comes from its seamless interoperability with data frame libraries like Polars and Pandas. Because they all share the Arrow in-memory format, conversions are often zero-copy and extremely fast. """ ) return @app.cell(hide_code=True) def _(mo): mo.md(r"### From DuckDB to Polars/Pandas") return @app.cell def _(pl, users_arrow_table): # Convert the Arrow table to a Polars DataFrame users_polars_df = pl.from_arrow(users_arrow_table) users_polars_df return (users_polars_df,) @app.cell def _(users_arrow_table): # Convert the Arrow table to a Pandas DataFrame users_pandas_df = users_arrow_table.to_pandas() users_pandas_df return (users_pandas_df,) @app.cell(hide_code=True) def _(mo): mo.md(r"### From Polars/Pandas to DuckDB") return @app.cell def _(pl): # Create a Polars DataFrame polars_df = pl.DataFrame({ "product_id": [101, 102, 103], "product_name": ["Laptop", "Mouse", "Keyboard"], "price": [1200.00, 25.50, 75.00] }) polars_df return (polars_df,) @app.cell(hide_code=True) def _(mo): mo.md(r"Now we can query this Polars DataFrame directly in DuckDB:") return @app.cell def _(mo, polars_df): # Query the Polars DataFrame directly in DuckDB mo.sql( f""" SELECT product_name, price FROM polars_df WHERE price > 50 ORDER BY price DESC; """ ) return @app.cell(hide_code=True) def _(mo): mo.md(r"Similarly, we can query a Pandas DataFrame:") return @app.cell def _(pd): # Create a Pandas DataFrame pandas_df = pd.DataFrame({ "order_id": [1001, 1002, 1003, 1004], "product_id": [101, 102, 103, 101], "quantity": [1, 2, 1, 3], "order_date": pd.to_datetime(['2024-01-15', '2024-01-16', '2024-01-16', '2024-01-17']) }) pandas_df return (pandas_df,) @app.cell def _(mo, pandas_df): # Query the Pandas DataFrame in DuckDB mo.sql( f""" SELECT order_date, SUM(quantity) as total_quantity FROM pandas_df GROUP BY order_date ORDER BY order_date; """ ) return @app.cell(hide_code=True) def _(mo): mo.md( r""" ## 4. Advanced Example: Combining Multiple Data Sources One of the most powerful features is the ability to join data from different sources (DuckDB tables, Arrow tables, Polars/Pandas DataFrames) in a single query: """ ) return @app.cell def _(mo, pandas_df, polars_df): # Join the DuckDB users table with the Polars products DataFrame and Pandas orders DataFrame result = mo.sql( f""" SELECT u.name as customer_name, p.product_name, o.quantity, p.price, (o.quantity * p.price) as total_amount FROM users u CROSS JOIN pandas_df o JOIN polars_df p ON o.product_id = p.product_id WHERE u.id = 1 -- Just for Alice ORDER BY o.order_date; """ ) result return (result,) @app.cell(hide_code=True) def _(mo): mo.md( r""" ## 5. Performance Benefits The Arrow format provides several performance benefits: - **Zero-copy data sharing**: Data can be shared between DuckDB and other Arrow-compatible systems without copying. - **Columnar format**: Efficient for analytical queries that typically access a subset of columns. - **Type safety**: Arrow's rich type system ensures data types are preserved across systems. """ ) return @app.cell(hide_code=True) def _(mo): mo.md(r"Let's create a larger dataset to demonstrate the performance:") return @app.cell def _(pl): import time # Create a larger Polars DataFrame large_polars_df = pl.DataFrame({ "id": range(1_000_000), "value": pl.Series([i * 2.5 for i in range(1_000_000)]), "category": pl.Series([f"cat_{i % 100}" for i in range(1_000_000)]) }) print(f"Created DataFrame with {len(large_polars_df):,} rows") return large_polars_df, time @app.cell def _(large_polars_df, mo, time): # Time a query on the large DataFrame start_time = time.time() result_large = mo.sql( f""" SELECT category, COUNT(*) as count, AVG(value) as avg_value, MIN(value) as min_value, MAX(value) as max_value FROM large_polars_df GROUP BY category ORDER BY count DESC LIMIT 10; """ ) query_time = time.time() - start_time print(f"Query completed in {query_time:.3f} seconds") result_large return query_time, result_large, start_time @app.cell(hide_code=True) def _(mo): mo.md( r""" ## Summary In this notebook, we've explored: 1. **Creating Arrow tables from DuckDB queries** using `.to_arrow()` 2. **Loading Arrow tables into DuckDB** and querying them directly 3. **Converting between DuckDB, Arrow, Polars, and Pandas** with zero-copy operations 4. **Combining data from multiple sources** in a single SQL query 5. **Performance benefits** of using Arrow's columnar format The seamless integration between DuckDB and Arrow-compatible systems makes it easy to work with data across different tools while maintaining high performance. """ ) return @app.cell def _(): import marimo as mo import pyarrow as pa import polars as pl import pandas as pd return mo, pa, pd, pl if __name__ == "__main__": app.run()