Re: Questions about Rollback - after insert, update, delete ... operations?

Bruno Wolff III <bruno(at)wolff(dot)to> writes:
>> I wasn't able to find where this is spelled out in the documentation,
>> but I believe all DDL commands except DROP DATABASE can be rolled back now.

> I don't think there's any all-in-one-place statement about it, but
> anything that doesn't explicitly object to being put inside a
> transaction block can be rolled back. Grepping for
> PreventTransactionChain, I see that the current suspects are

> CLUSTER (only the multi-table variants)
> CREATE DATABASE
> DROP DATABASE
> REINDEX DATABASE
> CREATE TABLESPACE
> DROP TABLESPACE
> VACUUM

As of 8.1, REINDEX SYSTEM needs to be listed as well.

In this context, it may be worth pointing out that CLUSTER, VACUUM, and
REINDEX are all *internally* roll-back-able, as is essential for crash
safety. The reason they object to being inside a transaction block is
that they want to start and end their own transactions internally so
that they can process each table in a separate transaction.

So, CREATE/DROP DATABASE and CREATE/DROP TABLESPACE really are the only
operations Postgres cannot roll back.

regards, tom lane