diff --git a/migrations/001.create-core.up.sql b/migrations/001.create-core.up.sql
index 10eaf059..20efb5bd 100644
--- a/migrations/001.create-core.up.sql
+++ b/migrations/001.create-core.up.sql
@@ -40,14 +40,12 @@ CREATE INDEX building_geometry_idx ON buildings ( geometry_id );
 -- Minimal user data to support login and edit history
 CREATE TABLE users (
     -- internal unique id
-    user_id serial PRIMARY KEY,
+    user_id uuid PRIMARY KEY,
     -- username for login (required)
-    username varchar UNIQUE NOT NULL,
+    username varchar(30) UNIQUE NOT NULL,
     -- email address for password reset (optional)
     email varchar(50),
-    -- salt - to be generated by application
-    salt varchar (20),
-    -- password - as generated application from hash(salt+password)
+    -- password - as generated from hash(salt+password) via pgcrypto
     pass varchar(60)
 );
 
@@ -65,11 +63,14 @@ CREATE TABLE log (
     -- default timestamp to time now
     log_timestamp TIMESTAMP default NOW(),
     -- log document to be extended in application
-    -- log change action (CREATE/UPDATE/DELETE)
+    -- log change diff (CREATE/UPDATE/DELETE)
     log_doc jsonb,
     -- log user id
-    user_id integer REFERENCES users
+    user_id uuid REFERENCES users,
+    -- log building id
+    building_id integer REFERENCES buildings
 );
 
 CREATE INDEX log_timestamp_idx ON log ( log_timestamp );
 CREATE INDEX log_user_idx ON log ( user_id );
+CREATE INDEX log_building_idx ON log ( building_id );