---
title: "What is a file cache?"
description: "A file cache keeps a local copy of media bytes so repeated transforms do not download the same object again."
url: "https://pixeltable.com/learn/what-is-a-file-cache"
updated: "2026-09-29"
vertical: "Storage"
doc: "https://docs.pixeltable.com/overview/quick-start"
---

# What is a file cache?

A file cache keeps a local copy of media bytes so repeated transforms do not download the same object again.

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

## On this page

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

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


- The first read fetches the object.
- Later reads of that object reuse the local bytes.
- Computed values are a different cache, on the row.

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

It is not the cache of computed-column results, and it is not a CDN edge cache.

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

|  | This | Not this |
| --- | --- | --- |
| Caches | Bytes of a file | Model outputs |
| Location | Near the engine | At a CDN edge |
| Invalidation | When the object changes | When a column expression changes |

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

Pixeltable’s file cache sits beside the catalog so frame extraction and similar work do not re-download the same clip.

## Questions {#questions}

### How does file cache work? {#faq-1}

The first read fetches the object. Later reads of that object reuse the local bytes. Computed values are a different cache, on the row.

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

It is not the cache of computed-column results, and it is not a CDN edge cache.

## Related

- [Documentation](https://docs.pixeltable.com/overview/quick-start)
- [Understanding Pixeltable Storage: The Four-Layer Architecture That Powers Multimodal AI](https://pixeltable.com/blog/understanding-pixeltable-storage-architecture)