diff --git a/src/config/env/index.ts b/src/config/env/index.ts
index 6d0ba0c..0b4fc36 100644
--- a/src/config/env/index.ts
+++ b/src/config/env/index.ts
@@ -26,6 +26,7 @@ const envSchema = z.object({
   POSTGRES_PASSWORD: z.string(),
   POSTGRES_DATABASE: z.string(),
   POSTGRES_HOST: z.string(),
+  SHADOW_DATABASE_URL: z.string().url(),
 
   NODE_ENV: z.enum(['development', 'production', 'test']),
   SPARKPOST_API_KEY: z.string(),
@@ -187,6 +188,14 @@ export const POSTGRES_DATABASE = parsed.data.POSTGRES_DATABASE;
  */
 export const POSTGRES_HOST = parsed.data.POSTGRES_HOST;
 
+/**
+ * The URL of another PostgreSQL database to shadow.
+ *
+ * @example
+ *   'postgresql://user:password@host:5432/database';
+ */
+export const SHADOW_DATABASE_URL = parsed.data.SHADOW_DATABASE_URL;
+
 /**
  * Node environment.
  *
diff --git a/src/prisma/schema.prisma b/src/prisma/schema.prisma
index e5ce2b4..6a84268 100644
--- a/src/prisma/schema.prisma
+++ b/src/prisma/schema.prisma
@@ -6,9 +6,10 @@ generator client {
 }
 
 datasource db {
-  provider  = "postgresql"
-  url       = env("POSTGRES_PRISMA_URL") // uses connection pooling
-  directUrl = env("POSTGRES_URL_NON_POOLING") // uses a direct connection
+  provider          = "postgresql"
+  url               = env("POSTGRES_PRISMA_URL") // uses connection pooling
+  directUrl         = env("POSTGRES_URL_NON_POOLING") // uses a direct connection
+  shadowDatabaseUrl = env("SHADOW_DATABASE_URL")
 }
 
 model User {
diff --git a/src/prisma/seed/clean/cleanDatabase.ts b/src/prisma/seed/clean/cleanDatabase.ts
index f62e49d..9b23d4b 100644
--- a/src/prisma/seed/clean/cleanDatabase.ts
+++ b/src/prisma/seed/clean/cleanDatabase.ts
@@ -13,8 +13,9 @@ const cleanDatabase = async () => {
       DO $$
       DECLARE
           statements CURSOR FOR
-              SELECT tablename FROM pg_tables
-              WHERE schemaname = 'public';
+            SELECT tablename FROM pg_tables
+            WHERE schemaname = 'public'
+            AND tablename != '_prisma_migrations';
       BEGIN
           FOR statement IN statements LOOP
               EXECUTE 'TRUNCATE TABLE ' || quote_ident(statement.tablename) || ' CASCADE;';