---
title: "How does rate limiting work for model APIs?"
description: "Rate limiting throttles and retries provider calls so a burst or an HTTP 429 does not fail the rows that could have waited."
url: "https://pixeltable.com/learn/what-is-rate-limiting"
updated: "2026-09-29"
vertical: "Orchestration"
doc: "https://docs.pixeltable.com/datastore/computed-columns"
---

# How does rate limiting work for model APIs?

Rate limiting throttles and retries provider calls so a burst or an HTTP 429 does not fail the rows that could have waited.

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

## On this page

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

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


- The engine limits how many calls are in flight.
- A 429 waits and retries that row.
- Other rows are not marked done if they never ran.

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

It is not DDoS protection, and it is not dropping failed rows forever.

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

|  | This | Not this |
| --- | --- | --- |
| Protects | Your provider quota | Your website from attackers |
| On 429 | Retry the row | Fail the pipeline |
| Scope | Model calls | Every HTTP request on the internet |

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

Pixeltable rate-limits provider calls made from computed columns so inserts do not stampede the API.

## Questions {#questions}

### How does rate limiting work? {#faq-1}

The engine limits how many calls are in flight. A 429 waits and retries that row. Other rows are not marked done if they never ran.

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

It is not DDoS protection, and it is not dropping failed rows forever.

## In the blog

- [Production-Grade Rate Limiting: How Pixeltable Handles API Failures](https://pixeltable.com/blog/production-rate-limiting)

## Related

- [Documentation](https://docs.pixeltable.com/datastore/computed-columns)
- [Production-Grade Rate Limiting: How Pixeltable Handles API Failures](https://pixeltable.com/blog/production-rate-limiting)
- [Incremental updates](https://pixeltable.com/use-cases/incremental-updates-ai-data-processing)