From 8fc291db4d8e04f9a0ff58f35dc971fc87ec4825 Mon Sep 17 00:00:00 2001
From: Etienne van Delden de la Haije <etienne@vandelden.family>
Date: Sun, 5 Jul 2026 09:07:12 +0200
Subject: [PATCH] Tune SQLite pragmas for dev/test/production to reduce lock
 contention

Adds temp_store/cache_size/wal_autocheckpoint tuning on top of Rails'
built-in WAL defaults, ties pool size to RAILS_MAX_THREADS, and loosens
synchronous/mmap_size/timeout in test to address the SQLite lock
contention that PARALLEL_WORKERS=1 currently works around.
---
 config/database.sqlite.yml | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/config/database.sqlite.yml b/config/database.sqlite.yml
index 38616e7430..3decd947f8 100644
--- a/config/database.sqlite.yml
+++ b/config/database.sqlite.yml
@@ -1,7 +1,14 @@
+default_pragmas: &default_pragmas
+  temp_store: memory
+  cache_size: -20000
+  wal_autocheckpoint: 10000
+
 default: &default
   adapter: sqlite3
-  pool: 5
+  pool: <%= ENV.fetch("RAILS_MAX_THREADS", 5) %>
   timeout: 5000
+  pragmas:
+    <<: *default_pragmas
 
 development:
   primary:
@@ -18,10 +25,20 @@ test:
     <<: *default
     database: storage/test.sqlite3
     schema_dump: schema_sqlite.rb
+    timeout: 20000
+    pragmas:
+      <<: *default_pragmas
+      synchronous: "off"
+      mmap_size: 268435456
   cable:
     <<: *default
     database: storage/test_cable.sqlite3
     migrations_paths: db/cable_migrate
+    timeout: 20000
+    pragmas:
+      <<: *default_pragmas
+      synchronous: "off"
+      mmap_size: 268435456
 
 production:
   primary: