--- title: "All Your GUCs in a Row: default_transaction_deferrable" url: https://daily.dev/posts/all-your-gucs-in-a-row-default-transaction-deferrable-cktpaq3fg source_url: https://postgr.es/p/9ma type: article source: "Planet PostgreSQL" published: 2026-06-17T01:05:27.991Z updated: 2026-06-17T01:32:09.533Z tags: ["postgresql"] reading_time: 4 upvotes: 0 comments: 0 language: 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. # All Your GUCs in a Row: default_transaction_deferrable **[Planet PostgreSQL](https://daily.dev/sources/planet-postgresql)** · 4 min read · 0 upvotes · 0 comments ## Summary A deep dive into PostgreSQL's `default_transaction_deferrable` GUC parameter, explaining that it only has effect when combined with SERIALIZABLE and READ ONLY transaction modes. The post covers how PostgreSQL's Serializable Snapshot Isolation (SSI) works, what 'safe snapshots' are, and how DEFERRABLE transactions wait for a safe snapshot to avoid predicate locks and serialization failures entirely. The recommendation is to leave the global default off and use the DEFERRABLE keyword per-transaction or per-role for dedicated reporting/backup connections against serializable workloads. ## 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: default\_transaction\_isolation and default\_transaction\_read\_only](https://daily.dev/posts/all-your-gucs-in-a-row-default-transaction-isolation-and-default-transaction-read-only-wzidpqlnd) · Planet PostgreSQL · 0 upvotes · 0 comments - [All Your GUCs in a Row: fsync](https://daily.dev/posts/all-your-gucs-in-a-row-fsync-6hzisw8sb) · Planet PostgreSQL · 0 upvotes · 0 comments --- Tags: [#postgresql](https://daily.dev/tags/postgresql) [View this post on daily.dev](https://daily.dev/posts/all-your-gucs-in-a-row-default-transaction-deferrable-cktpaq3fg)