🪶 Apache Arrow: The Modern Memory Format Powering Analytical Engines

Apache Arrow is an in-memory columnar data format optimized for analytical workloads. It enables fast data access, zero-copy reads, and efficient interoperability between systems like Pandas, DuckDB, Polars, and query engines like Apache DataFusion. If you’ve used PyArrow, Polars, or Arrow arrays in Rust, you’ve already felt its power.

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🚨 The Problem: Bottlenecks in Data Analytics

For years, analytical engines have faced a fundamental challenge: how to process massive datasets in memory efficiently.

Traditional formats like CSV or even JSON:

• Are row-oriented (bad for analytics)

• Require parsing + decoding before processing

• Don't support vectorized execution or SIMD

Even columnar formats like Parquet are designed for storage, not runtime execution.

What we needed was a standard, fast, language-agnostic format for in-memory columnar data.

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🚀 Enter Apache Arrow

Apache Arrow was born to solve this. It's a language-independent specification and implementation for:

• In-memory columnar data layout

• Zero-copy reads and writes

• Interoperability between systems and languages

• Support for modern CPU hardware (SIMD, caches)

Arrow is not a database, and not a query engine—it's the foundation those tools build on.

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🧠 Core Concepts in Arrow

🧱 1. Columnar Format

Arrow stores data by column, not by row. This means:

• Better cache locality

• Vectorized execution (e.g., compute on whole columns at once)

• Efficient compression

🪵 2. RecordBatch

A RecordBatch in Arrow is like a table in memory:

• It contains a schema (field names and types)

• And a set of column arrays
  Each column is an ArrowArray, backed by contiguous memory buffers.

🧩 3. Buffers

Each column has:

• A data buffer (the actual values)

• A null bitmap buffer (to track missing values)

• An optional offset buffer (for variable-width types like strings)

📚 4. Language Bindings

Arrow is implemented in:

• C++

• Rust

• Python (via PyArrow)

• Go, Java, and more

This means a dataset generated in Rust can be read directly in Python or Go without copying or converting.

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🔥 Real-World Use Cases

📊 Pandas + PyArrow

PyArrow allows Arrow arrays to be passed to/from Pandas and NumPy without copying, speeding up IO and interoperability.

🦆 DuckDB

DuckDB uses Arrow to interface with Python, R, and even web clients. When you call .arrow() on a DuckDB result, you get a zero-copy view.

⚙️ Apache DataFusion

DataFusion is a Rust-based SQL engine that processes RecordBatch Arrow data. Its entire physical execution plan is Arrow-native.

🐻‍❄️ Polars

Polars uses Arrow arrays under the hood for lightning-fast, multi-threaded, Rust-native DataFrame processing.

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TL;DR: Use Parquet to store data, use Arrow to process it.

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🧪 Example: Arrow in Rust

use arrow::array::{Int32Array, Array};
use arrow::record_batch::RecordBatch;
use arrow::datatypes::{DataType, Field, Schema};
use std::sync::Arc;

fn main() {
    let data = Int32Array::from(vec![Some(1), None, Some(3)]);
    let field = Field::new("numbers", DataType::Int32, true);
    let schema = Arc::new(Schema::new(vec![field]));
    let batch = RecordBatch::try_new(schema, vec![Arc::new(data)]).unwrap();

    println!("Rows: {}", batch.num_rows());
    println!("Columns: {}", batch.num_columns());
}

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🧵 Summary

Apache Arrow is the backbone of modern data systems:

• Columnar + cache-efficient layout

• Language-agnostic zero-copy interoperability

• Powering analytical engines from Polars to DuckDB

It's not just a data format—it's a standard for high-performance analytics.

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🔗 References

• Apache Arrow Official Site

• Arrow Rust Docs

• Apache DataFusion

• https://duckdb.org/2021/12/03/duck-arrow.html

  ✨ About the Author

  I'm Jagdish Parihar, a backend engineer passionate about high-performance systems, distributed databases, and query engines.

  I've contributed to Apache DataFusion, focusing on SQL engine internals like custom aggregate functions and optimizer rule enhancements. I'm also exploring Apache Arrow in Rust as part of building scalable analytical systems.

  You can find me here:

  • 🌐 LinkedIn

  • 🧑‍💻 GitHub

  • 📬 jatin6972@gmail.com

If you’re building something cool with Arrow, DataFusion, or Rust — let’s connect!