Add last_seen timestamp

audit/changed_tables

@@ -42,11 +42,20 @@ except Exception as e:
                     table_schema text,
                     table_name text,
                     ts timestamptz,
+                    last_seen timestamptz,
                     sha256 text
                 )
                 """
         )
     db.commit()
+try:
+    csr.execute("select last_seen from " + audit_table)
+    csr.fetchone()
+except Exception as e:
+    db.rollback()
+    csr.execute("alter table " + audit_table + " add column last_seen timestamptz")
+    db.commit()
+
 
 csr.execute("select * from information_schema.tables where table_schema = %s", (a.schema,))
 
@@ -74,9 +83,14 @@ for table in csr.fetchall():
     old = csr.fetchone()
     if not old or old.sha256 != digest:
         print(" changed", digest, end="")
-        q = "insert into {audit_table}(table_schema, table_name, ts, sha256) values(%s, %s, now(), %s)".format(audit_table=audit_table)
+        q = "insert into {audit_table}(table_schema, table_name, ts, last_seen, sha256) values(%s, %s, now(), now(), %s)".format(audit_table=audit_table)
         csr.execute(q, (table.table_schema, table.table_name, digest))
         db.commit()
+    else:
+        print(" unchanged", digest, end="")
+        q = "update {audit_table} set last_seen=now() where id = %s".format(audit_table=audit_table)
+        csr.execute(q, (old.id,))
+        db.commit()
     db.rollback() # to close transaction
     print(flush=True)