--- a/postgres.rst	Tue Jan 08 11:45:14 2019 +0200
+++ b/postgres.rst	Wed Jan 09 19:32:16 2019 +0200
@@ -67,6 +67,13 @@
 
    SELECT * FROM pg_available_extensions;
 
+Limitations
+===========
+
+https://wiki.postgresql.org/wiki/TOAST
+  TOAST is a mechanism PostgreSQL uses to keep physical data rows from exceeding the size of a data
+  block (typically 8KB).
+
 Grant role options
 ==================
 ::
@@ -252,6 +259,8 @@
   SELECT pg_database_size('geekdb');  -- in bytes
   SELECT pg_size_pretty(pg_database_size('dbname'));
 
+  SELECT datname, pg_database_size(datname) FROM pg_database;
+
 List of databases sizes::
 
   \l+