# Concurrency vs. Throughput: why more parallelism can make databases slower

DevFeed: [Concurrency vs. Throughput: why more parallelism can make databases slower](<https://devfeed.tech/articles/concurrency-vs-throughput-why-more-parallelism-can-make-databases-slower-2321.md>)

Original publisher: [Read original article](<https://planetscale.com/blog/concurrency-vs-throughput-vitess-mysql>)

Author: Liz van Dijk

Published: 2026-08-07T00:00:00Z

Content type: article

Language: en

Sources: [Blog -- PlanetScale](<https://devfeed.tech/sources/blog-planetscale.md>)

Topics: [Databases](<https://devfeed.tech/topics/databases.md>), [MySQL](<https://devfeed.tech/topics/mysql.md>), [vitess](<https://devfeed.tech/topics/vitess.md>), [Concurrency](<https://devfeed.tech/topics/concurrency.md>), [bug](<https://devfeed.tech/topics/bug.md>), [Cloud](<https://devfeed.tech/topics/cloud.md>)

Tags: [bug](<https://devfeed.tech/tags/bug.md>), [cloud](<https://devfeed.tech/tags/cloud.md>), [concurrency](<https://devfeed.tech/tags/concurrency.md>), [databases](<https://devfeed.tech/tags/databases.md>), [engineering](<https://devfeed.tech/tags/engineering.md>), [mysql](<https://devfeed.tech/tags/mysql.md>), [vitess](<https://devfeed.tech/tags/vitess.md>)

## AI overview

Increasing database parallelism can reduce throughput and destabilize a production system. The article examines how a long-running MySQL transaction, growing version history, retries, and an uncapped request surge caused widespread failures, and explains how Vitess transaction timeouts and connection-pool limits can contain the impact.

## Source excerpt

Increasing throughput sometimes requires reducing parallelism. A look into why this is the case for Vitess + MySQL databases