Re: [HACKERS] Nested Transaction TODO list

[Oliver Jowett]

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
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