---
title: "What is reproducibility in a data pipeline?"
description: "Reproducibility means you can inspect the same inputs and column definitions and get the same cached outputs, or a known diff."
url: "https://pixeltable.com/learn/what-is-reproducibility"
updated: "2026-09-29"
vertical: "Versioning"
doc: "https://docs.pixeltable.com/overview/quick-start"
---

# What is reproducibility in a data pipeline?

Reproducibility means you can inspect the same inputs and column definitions and get the same cached outputs, or a known diff.

Updated: 2026-09-29
Part of [What is time travel?](https://pixeltable.com/learn/what-is-time-travel).

## On this page

- [How it works](https://pixeltable.com/learn/what-is-reproducibility#how-it-works)
- [What it is not](https://pixeltable.com/learn/what-is-reproducibility#what-it-is-not)
- [Comparison](https://pixeltable.com/learn/what-is-reproducibility#comparison)
- [Where Pixeltable fits](https://pixeltable.com/learn/what-is-reproducibility#where-pixeltable-fits)
- [Questions](https://pixeltable.com/learn/what-is-reproducibility#questions)

## How it works {#how-it-works}


- Inputs are versioned rows.
- Expressions are the column definitions.
- Caches mean a rerun does not call the model again unless an input changed.

## What it is not {#what-it-is-not}

It is not only setting a random seed in a training script.

## reproducibility: this, and the thing it is confused with {#comparison}

|  | This | Not this |
| --- | --- | --- |
| Same inputs | Same cached outputs | A new sample from the model |
| Diff | Visible between versions | A different notebook result |
| Seed | Not the whole story | The usual ML lever |

## Where Pixeltable fits {#where-pixeltable-fits}

Pixeltable caches computed columns and versions the table, which is what makes a rerun comparable.

## Questions {#questions}

### How does reproducibility work? {#faq-1}

Inputs are versioned rows. Expressions are the column definitions. Caches mean a rerun does not call the model again unless an input changed.

### What is reproducibility often confused with? {#faq-2}

It is not only setting a random seed in a training script.

## In the blog

- [Pixeltable's Time Travel: Advanced Versioning for Fearless AI Development](https://pixeltable.com/blog/pixeltable-versioning-time-travel)

## Related

- [Documentation](https://docs.pixeltable.com/overview/quick-start)
- [Pixeltable's Time Travel: Advanced Versioning for Fearless AI Development](https://pixeltable.com/blog/pixeltable-versioning-time-travel)
- [What ML Infrastructure Engineers Actually Want: Design Principles for Modern AI Data Platforms](https://pixeltable.com/blog/ml-infrastructure-design-principles-evaluation)