--- title: The Insatiable Postgres Replication Slot | daily.dev description: An investigation into unexpected disk space exhaustion on an Amazon RDS Postgres instance caused by an inactive logical replication slot. The root cause is a... canonical: https://daily.dev/posts/the-insatiable-postgres-replication-slot-nap6xavop twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: The Insatiable Postgres Replication Slot | daily.dev og:description: An investigation into unexpected disk space exhaustion on an Amazon RDS Postgres instance caused by an inactive logical replication slot. The root cause is a... og:url: https://daily.dev/posts/the-insatiable-postgres-replication-slot-nap6xavop og:image: https://api.daily.dev/og/posts/NAp6XAVoP.png og:image:alt: The Insatiable Postgres Replication Slot og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # The Insatiable Postgres Replication Slot **[Gunnar Morling](https://daily.dev/sources/gunnar-morling)** · 6 min read · 0 upvotes · 0 comments ## Summary An investigation into unexpected disk space exhaustion on an Amazon RDS Postgres instance caused by an inactive logical replication slot. The root cause is a combination of three factors: RDS writes heartbeats to an internal rdsadmin database every 5 minutes, RDS configures the WAL segment size to 64 MB (vs. the default 16 MB), and the archive_timeout parameter forces a new WAL segment every 5 minutes when there is any database activity. An inactive replication slot retains all these 64 MB WAL segments, leading to ~18 GB/day of disk growth on an otherwise idle database. The fix is to never leave replication slots unattended, set up alerts on WAL retention per slot, and use pg_logical_emit_message() to periodically advance an otherwise stalled slot. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [All Your GUCs in a Row: idle\_replication\_slot\_timeout](https://daily.dev/posts/all-your-gucs-in-a-row-idle-replication-slot-timeout-5ezg0va9j) · Planet PostgreSQL · 0 upvotes · 1 comments - [The Night Our Tables Wouldn't Stop Growing](https://daily.dev/posts/the-night-our-tables-wouldn-t-stop-growing-pvfggogkk) · Planet PostgreSQL · 1 upvotes · 0 comments - [When Patroni Silently Deletes Your Replication Slots](https://daily.dev/posts/when-patroni-silently-deletes-your-replication-slots-elvtrgz86) · Planet PostgreSQL · 0 upvotes · 0 comments --- Tags: [#aws](https://daily.dev/tags/aws), [#postgresql](https://daily.dev/tags/postgresql), [#debezium](https://daily.dev/tags/debezium) [View this post on daily.dev](https://daily.dev/posts/the-insatiable-postgres-replication-slot-nap6xavop) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"The Insatiable Postgres Replication Slot","url":"https://daily.dev/posts/the-insatiable-postgres-replication-slot-nap6xavop","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/the-insatiable-postgres-replication-slot-nap6xavop"},"datePublished":"2026-03-16T08:14:53.245Z","dateModified":"2026-03-16T08:22:37.257Z","description":"An investigation into unexpected disk space exhaustion on an Amazon RDS Postgres instance caused by an inactive logical replication slot. 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