Re: [boost] [rdb] 0.0.09

Subject: Re: [boost] [rdb] 0.0.09
From: Jean-Louis Leroy (jl_at_[hidden])
Date: 2009-09-28 12:26:49

> Concerning the transactions, I thought ODBC already was the common 
> interface beginning, committing and rollingback transactions. Please 
> see functions SQLSetConnectAttr SQLEndTran
That's how they are implemented in the current drop. However, my plan is 
to support native bindings. In ODBC a transaction looks like this :

    set autocommit off
    do work
    commit or roll back
    do work
    commit or roll back
    etc

This pattern is directly reflected in the current implementation. See 
the test suite in libs/rdb/test/test_odbc.cpp.

Other vendors may have a different pattern :

    begin transaction
    do work
    commit or roll back
     begin transaction
    do work
    commit or roll back

Of course I could say that all backends have three functions : 
start_transaction, commit and rollback. In the case of ODBC 
start_transaction would be a no-op. Or maybe it would turn auto-commit 
off (and throw if the underlying db is not tx-capable). But I am 
hesitating a bit. The current philosophy of my lib is much like C's : 
you look at any piece of code and you know exactly how it will translate 
into machine code. No hidden 17 dtor calls hidden inside a closing 
brace. From that point you either use rdb to write apps or as a 
foundation to build higher-level tools.

OTOH maybe I'm splitting hairs wrt transactions. Besides the two 
patterns above, does anybody see a third possibility ? Nested 
transactions ? They fit nicely in the second pattern...

J-L