[m-users.] ODBC library: Ony one transaction per connection .. ?

[Volker Wysk]

Hi.

I've found this in the implementation part of odbc.m:

transaction(Source, User, Password, Closure, Result, !IO) :-
    %
    % We could have separate open and close connection predicates in the
    % interface, but that would just be more effort for the programmer
    % for a very minor efficiency gain. The connection time will be
    % insignificant for even trivial queries.
    %

This explains why there's only one transcation per connection, but it's
completely contrary to what I've heard. AFAIK opening a connection is an
expensive operation...

Confused, Volker


Am Montag, dem 17.01.2022 um 09:47 +0100 schrieb Volker Wysk:
> Hi!
> 
> I've found this in odbc.m:
> 
>     % odbc.transaction(Source, UserName, Password, Transaction, Result).
>     %
>     % Open a connection to `Source' using the given `UserName'
>     % and `Password', perform `Transaction' within a transaction
>     % using that connection, then close the connection.
> 
> And there aren't any predicates for opening and closing a connection...
> 
> So you really need a new connection for every transaction ??  Is the ODBC
> library only meant as a tool, to demonstrate what's written in the research
> paper "Database transactions in a purely declarative logic programming
> language" ?
> 
> Bye, Volker
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