how does postgreSQL 8 handle concurrency control

Question

Am using postgreSQL 8 to create a database. I have noticed that it migt suffer a problem with concurrency control.
1. please explain to me how does postgreSQL 8 handle concurrency control? 2. when comparing MY SQL with postgreSQL which of these is best to handle concurrency control.

Answer 1

PostgreSQL 8 does not exist, you have 8.0, 8.1, 8.2, 8.3 and 8.4. All different major versions. Version 9.0 will be released this month.

PostgreSQL uses MVCC (Multiversion Concurrency Control), as described in the manual: http://www.postgresql.org/docs/current/interactive/mvcc.html

MySQL uses per engine a different stategy, innoDB also uses MVCC. Major difference will be that in PostgreSQL, everything is transaction safe, including DDL like ALTER TABLE.

I have noticed that it migt suffer a problem with concurrency control.

What did you notice? MVCC is a smart system, not a perfect system. But it's good enough for many databases, like Oracle and Firebird.