From 1ce39c8e76bee5819d0f891bb9c292552e156687 Mon Sep 17 00:00:00 2001
From: Sadie Powell <sadie@witchery.services>
Date: Mon, 10 Nov 2025 17:16:21 +0000
Subject: [PATCH] Add an option to not preserve old data in db_json.

---
 data/anope.example.conf      | 12 ++++++++++++
 modules/database/db_json.cpp |  4 ++++
 2 files changed, 16 insertions(+)

diff --git a/data/anope.example.conf b/data/anope.example.conf
index 19476c039..6ddec1ec6 100644
--- a/data/anope.example.conf
+++ b/data/anope.example.conf
@@ -1147,8 +1147,20 @@ module
 	 * Allows Anope to continue writing the database even if the original can
 	 * not be backed up. This is not recommended as it may result in total data
 	 * loss during the circumstances described above.
+	 *
+	 * Defaults to no.
 	 */
 	#ignore_backup_failure = yes
+
+	/*
+	 * Whether to preserve unknown data within the database. When a module is
+	 * unloaded its data will be kept in the database so that it continues to
+	 * function when reloaded. You can turn this off to clean up unknown data
+	 * on the next database write.
+	 *
+	 * Defaults to yes.
+	 */
+	#preserve_unknown_data = no
 }
 
 /*
diff --git a/modules/database/db_json.cpp b/modules/database/db_json.cpp
index 9fba40b84..d2aa5fe85 100644
--- a/modules/database/db_json.cpp
+++ b/modules/database/db_json.cpp
@@ -363,6 +363,10 @@ public:
 
 	void OnSaveDatabase() override
 	{
+		// Step 0: clear the old data if we don't want to preserve it.
+		if (!Config->GetModule(this).Get<bool>("preserve_unknown_data", "yes"))
+			databases.clear();
+
 		// Step 1: clear the old data.
 		for (const auto &type : Serialize::Type::GetTypeOrder())
 		{