# Mastering Postgres Replication Slots: Preventing WAL Bloat and Other Production Issues

DevFeed: [Mastering Postgres Replication Slots: Preventing WAL Bloat and Other Production Issues](<https://devfeed.tech/articles/mastering-postgres-replication-slots-preventing-wal-bloat-and-other-production-issues-18851.md>)

Original publisher: [Read original article](<https://www.morling.dev/blog/mastering-postgres-replication-slots/>)

Published: 2025-07-08T11:55:00Z

Content type: tutorial

Language: en

Sources: [Gunnar Morling](<https://devfeed.tech/sources/gunnar-morling.md>)

Topics: [Replication](<https://devfeed.tech/topics/replication.md>), [Databases](<https://devfeed.tech/topics/databases.md>), [Monitoring](<https://devfeed.tech/topics/monitoring.md>)

Tags: [best-practices](<https://devfeed.tech/tags/best-practices.md>), [database](<https://devfeed.tech/tags/database.md>), [debezium](<https://devfeed.tech/tags/debezium.md>), [failover](<https://devfeed.tech/tags/failover.md>), [monitoring](<https://devfeed.tech/tags/monitoring.md>), [postgres](<https://devfeed.tech/tags/postgres.md>), [production](<https://devfeed.tech/tags/production.md>), [replication](<https://devfeed.tech/tags/replication.md>)

## AI overview

This practical guide explains how to manage Postgres replication slots for Change Data Capture pipelines and reduce excessive write-ahead log retention. It covers decoding plug-ins, heartbeats, failover, publications, filtering, replica identity, monitoring, and removing unused slots, with examples based primarily on Debezium's Postgres connector.

## Source excerpt

Table of Contents Use the pgoutput Logical Decoding Output Plug-in Define a Maximum Replication Slot Size Enable Heartbeats Use Table-level Publications Use Column and Row Filters Enable Fail-Over Slots Consider Using Replica Identity FULL Monitor, Monitor, Monitor! Drop Unused Replication Slots Summary Over the last couple of years, I've helped dozens of users and organizations to build Change Data Capture (CDC) pipelines for their Postgres databases. A key concern in that process is setting up and managing replication slots, which are Postgres' mechanism for making sure that any segments of the write-ahead log (WAL) of the database are kept around until they have been processed by registered replication consumers. When not being careful, a replication slot may cause unduly large amounts of WAL segments to be retained by the database. This post describes best practices helping to prevent this and other issues, discussing aspects like heartbeats, replication slot failover, monitoring, the management of Postgres publications, and more. While this is primarily based on my experience of using replication slots via Debezium's Postgres connector, the principles are generally applicable and are worth considering also when using other CDC tools for Postgres based on logical replication.