Re: Nested Transaction TODO list

Alvaro Herrera wrote:

>>One generalization of this to nested transactions would be:
>>
>> SUBBEGIN [transactionname]
>> SUBCOMMIT [transactionname]
>> SUBABORT [transactionname]
>
>
> The only departure from the SAVEPOINT syntax is that you are able to
> "subcommit" a savepoint. Not sure how useful that is ...

One thing SUBCOMMIT [name] does allow is discarding savepoints / named
txns without rolling back their changes. That might be useful if we
allow nesting of names, e.g.:

SAVEPOINT save1
-- do work #1
SAVEPOINT save1 -- hides the earlier SAVEPOINT
-- do work #2
SAVEPOINT save2
-- do work #3
SUBCOMMIT save1 -- provisionally commits #2 and #3 to enclosing txn
-- do work #4
ROLLBACK TO save1 -- rolls back #1, #2, #3, #4

Other than that.. I assume we want SUBBEGIN/SUBCOMMIT/SUBABORT
regardless of how we do savepoints. Since savepoints are a subset of
what you can do with nested transactions, it seems appropriate that
SUBBEGIN etc. can do everything that savepoints can -- i.e. naming of
savepoints/transactions. And then SUBCOMMIT [name] is just there for
completeness.

-O