why is rollback necessary

Observe the following code :

$dbh->begin_work;

eval {
do_some_db_stuff();
$dbh->commit;
};

if ($@) {
eval { $dbh->rollback(); };
} else {
print "committed\n";
}

Is the $dbh->rollback() necessary? if $dbh->commit fails
then the data never got committed, so what is the point of
calling $dbh->rollback ? Is the transaction kept open
otherwise ?


Thanks

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Re: why is rollback necessary

On Wed, 5 May 2004, mayuran wrote:

> Observe the following code :
>
> $dbh->begin_work;
>
> eval {
> do_some_db_stuff();
> $dbh->commit;
> };
>
> if ($@) {
> eval { $dbh->rollback(); };
> } else {
> print "committed\n";
> }
>
> Is the $dbh->rollback() necessary? if $dbh->commit fails
> then the data never got committed, so what is the point of
> calling $dbh->rollback ? Is the transaction kept open
> otherwise ?

Yes you still need to call rollback() because 1. It is not only the commit that
can fail in your example. 2. Think about this case.. $dbh->commit() fails but
later in your program you have a $dbh->commit that succeds.



Rudy


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Re: why is rollback necessary

On Wed, 5 May 2004, mayuran wrote:

> Observe the following code :
>
> $dbh->begin_work;
>
> eval {
> do_some_db_stuff();
> $dbh->commit;
> };
>
> if ($@) {
> eval { $dbh->rollback(); };
> } else {
> print "committed\n";
> }
>
> Is the $dbh->rollback() necessary? if $dbh->commit fails
> then the data never got committed, so what is the point of
> calling $dbh->rollback ? Is the transaction kept open
> otherwise ?

Yes you still need to call rollback() because 1. It is not only the commit that
can fail in your example. 2. Think about this case.. $dbh->commit() fails but
later in your program you have a $dbh->commit that succeds.



Rudy


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