Обсуждение: BUG #13038: Unobvious snapshotting behavior on altered tables
The following bug has been logged on the website: Bug reference: 13038 Logged by: Alexey Bashtanov Email address: bashtanov@imap.cc PostgreSQL version: 9.4.1 Operating system: Linux CentOS 6.5 x64 Description: Hello! On truncate statement docs page there is a nice pink warning http://www.postgresql.org/docs/9.4/static/sql-truncate.html#AEN85039 This warning also affects some table-rewriting ALTER TABLE statement, see http://johtopg.blogspot.com.br/2014/11/postgresql-gotcha-of-week-week-45_6.html The problem is 1) This is undocumented. Please document which commands can lead to this behavior. 2) Not all the table-rewriting statements can show an empty snapshot. ALTER TABLE ADD COLUMN, ALTER TABLE SET WITH/WITHOUT OIDS and TRUNCATE surely can. ALTER TABLE SET TABLESPACE, CLUSTER, VACUUM FULL probably cannot. What is the difference between the commands in the first list and in the second one? Maybe this annoying behavior can be fixed for all DDL statements? Best Regards Alexey Bashtanov