Changes between Version 18 and Version 19 of Performance

Timestamp:

Nov 4, 2013, 2:06:36 PM (11 years ago)

Author:

miracee

Comment:

—

Performance

@@ -141 +141 @@
 * In PostgreSQL version >= 9.2 you need to cast relpages to NUMERIC because the function changed to pg_size_pretty(NUMERIC).
 
+* Tables and indexes starting with pg_ usually are tables created by the postgresql system
+* pg_largeobject belongs to the tables created by postgresql
+* oid for objects created by the postgresql system are lower then the database oid
+* oid from your own tables and indexes always are bigger then the database oid
+
+When you just want to list all your own tables and indexes plus the toast tables that were created for that tables / indexes:
+{{{
+... WHERE oid > DATABASE_OID;
+}}}
+
+When you want to get informations about pg_largobject:
+{{{
+... WHERE relname LIKE '%large%';
+}}}
+
+=== TOAST ===
+
+* The Oversize Attribute Storage Technique
+* Used on variable length data types (e.g. varchar, text, bytea)
+** PostgreSQL creates pg_toast_* tables here which are empty as long as data won't exceed page size
+* If tuple exceeds page size (8 kB by default)
+** data will get compressed 
+** data will be broken into multiple rows
 
 == Size of RASBASE tables ==