1 files changed, 2 insertions, 1 deletions
diff --git a/src/schema.sql b/src/schema.sql
index cd67530..1104551 100644
--- a/src/schema.sql
+++ b/src/schema.sql
@@ -51,7 +51,8 @@ CREATE TABLE Outputs (
 );
 
 CREATE TABLE Builds (
-  derivation    TEXT NOT NULL PRIMARY KEY,
+  id            INTEGER NOT NULL PRIMARY KEY,
+  derivation    TEXT NOT NULL UNIQUE,
   evaluation    INTEGER NOT NULL,
   job_name      TEXT NOT NULL,
   system        TEXT NOT NULL,