Yes, but this violates ACID principles. As Igor pointed out this does not resemble a full implementation of transactions, as nested transactions can be commited and rolled back independently of the outer parent transaction.
Mike -----Ursprüngliche Nachricht----- Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Gesendet: Montag, 9. April 2007 18:38 An: sqlite-users@sqlite.org Cc: Dennis Cote Betreff: Re: [sqlite] SQLite and nested transactions So. If i read this code right. * The transaction_level keeps track of how many nested transactions have occurred. * Only the parent transaction allows the commit. In this case, only a single journal is required (the parent journal). Thanks, Ray ---- Dennis Cote <[EMAIL PROTECTED]> wrote: > Darren Duncan wrote: > > > > I will clarify that child transactions are just an elegant way of > > partitioning a larger task, and that parent transactions always > > overrule children; even if a child transaction commits successfully, > > a rollback of its parent means there are no lasting changes. > Darren, > > Because of this, and the fact that a transaction is basically a > guarantee that all or none of the enclosed statements are executed, it > is much simpler to implement nested transactions using a counter and > the existing transaction API in a set of wrapper functions. There is > no need to maintain all the intermediate state information. All you > need to know is the current nesting level, and if any enclosed > transaction was rolled back. > > The following code shows the basic process. > > int transaction_level = 0; > bool transaction_failed; > > void begin_nested_transaction() > { > if (transaction_level++ == 0) { > transaction_failed = false; > sqlite3_exec("begin"); > } > } > > void commit_nested_transaction() > { > if (--transaction_level == 0) > if (transaction_failed) > sqlite3_exec("rollback"); > else > sqlite3_exec("commit"); > } > > void rollback_nested_transaction() > { > transaction_failed = true; > commit_transaction(); > } > > HTH > Dennis Cote > > ---------------------------------------------------------------------- > ------- To unsubscribe, send email to > [EMAIL PROTECTED] > ---------------------------------------------------------------------- > ------- > ---------------------------------------------------------------------------- - To unsubscribe, send email to [EMAIL PROTECTED] ---------------------------------------------------------------------------- - ----------------------------------------------------------------------------- To unsubscribe, send email to [EMAIL PROTECTED] -----------------------------------------------------------------------------
