2009/11/30 张茂森 <maosen(dot)zhang(at)alibaba-inc(dot)com>:
>
pgsql-hackers is not the right place for user questions; try
pgsql-general or pgsql-novice.
The answer to your question is in the documentation. You can find it here:
http://www.postgresql.org/docs/8.4/static/transaction-iso.html#MVCC-SERIALIZABILITY
...Robert