Does Postgres support nested or autonomous transactions?

Question

I have situation in which I have to commit a portion of code as transaction of its own.
I have created a table subtransaction_tbl:

CREATE TA         


        

Answer 1

Postgres does support nested transactions, but they differ from the conventional SQL, more like transactions with nested partial points.

On the top level you always have your typical BEGIN/COMMIT/ROLLBACK, and on nested levels you have to use the following commands:

• SAVEPOINT name - creates a new savepoint, with name unique for the transaction
• RELEASE SAVEPOINT name - commits the savepoint, though it will only persist if the containing transaction commits
• ROLLBACK TO SAVEPOINT name - rolls back the savepoint

You would also have to make sure that:

• The names used for each SAVEPOINT are unique;
• Failure in one SAVEPOINT is propagated upwards to the top level.

The last bit is a bit tricky, unless you use a library that can do that for you automatically.

When I wrote pg-promise, I made sure that those two provisions are guaranteed:

• It generates save-point names automatically, as level_1, level_2, and so on, based on the transaction level;
• It executes containing ROLLBACK TO SAVEPOINT name, plus the top-level ROLLBACK in case a child transaction fails - all built on the standard promise-chaining logic.

See also the limitations of the PostgreSQL nested transactions explained...