Re: define transaction within pg/psql. Necessary?

all statements in postgresql are self contained transactions, and you cannot change that.
To answer your question directly, you don't have to, it will all be a transaction.

The best example of that is to run following query in psql:

CREATE TEMP TABLE foo() ON COMMIT DROP;


the table will not exists anymore after running it. Precisely because it was 'automatically' wrapped in begin/commit, and dropped at the end of it.


hth