# The dangers of Postgres subtransactions

DevFeed: [The dangers of Postgres subtransactions](<https://devfeed.tech/articles/the-dangers-of-postgres-subtransactions-2335.md>)

Original publisher: [Read original article](<https://planetscale.com/blog/the-dangers-of-postgres-subtransactions>)

Author: Etienne Berube

Published: 2026-08-11T00:00:00Z

Content type: article

Language: en

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

Topics: [PostgreSQL](<https://devfeed.tech/topics/postgresql.md>), [postgresql clusters](<https://devfeed.tech/topics/postgresql-clusters.md>), [Database](<https://devfeed.tech/topics/database.md>), [Server](<https://devfeed.tech/topics/server.md>), [data](<https://devfeed.tech/topics/data.md>)

Tags: [availability](<https://devfeed.tech/tags/availability.md>), [data](<https://devfeed.tech/tags/data.md>), [database](<https://devfeed.tech/tags/database.md>), [engineering](<https://devfeed.tech/tags/engineering.md>), [postgres](<https://devfeed.tech/tags/postgres.md>), [postgresql](<https://devfeed.tech/tags/postgresql.md>), [server](<https://devfeed.tech/tags/server.md>)

## AI overview

Postgres subtransactions can reduce throughput across an entire PostgreSQL cluster and prevent newly added read replicas from accepting queries. The article explains how replicas replay the primary's WAL and determine when they can safely serve reads.

## Source excerpt

Subtransactions can slow down your entire PostgreSQL server and break your high availability strategy by keeping new read replicas from accepting connections.