I'm still learning how databases and transactions work so bear with me.
How does error handling work?
If I have 5 nested transactions and the 5th transaction fails is this
transaction failure supposed to be communicated to the parent or does the
fourth transaction try to do error recovery?
Ray
> Date: Mon, 9 Apr 2007 9:38:16 -0700
> From: <[EMAIL PROTECTED]>
> To: sqlite-users@sqlite.org
> Cc: Dennis Cote <[EMAIL PROTECTED]>
> Subject: 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
> >
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>
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