On Wed, 9 Mar 2005 19:34:51 -0800, Jonathan Leffler <[EMAIL PROTECTED]> wrote:
> On Wed, 9 Mar 2005 09:47:20 +0100, H.Merijn Brand <[EMAIL PROTECTED]> > wrote: > > On Tue, 8 Mar 2005 12:12:23 -0800, Jonathan Leffler > > <[EMAIL PROTECTED]> wrote: > > > On Tue, 8 Mar 2005 11:01:48 +0000, Tim Bunce <[EMAIL PROTECTED]> > > > wrote: > > > > On Mon, Mar 07, 2005 at 11:47:32PM -0000, Greg Sabino Mullane wrote: > > > > > > While I don't have any particular objections, doesn't > > > > > > Pg (and most other DBMSs supporting savepoints) have > > > > > > SQL syntax to implement them ? If so, isn't just > > > > > > > > > > > > $dbh->do(<savepoint-sql>) > > > > > > > > > > > > sufficient ? > > > > > > > > > > Sure, but they also have syntax to implement BEGIN and ROLLBACK. > > > > > > It isn't wholly clear why we have $dbh->commit an $dbh->rollback; both > > > could be simulated with $dbh->do on most databases. However, there is > > > some minor performance advantage on some systems. For example, IBM > > > Informix Dynamic Server (IDS) recognizes those statements in ESQL/C > > > and the SQLI protocol used to transfer commands between client code > > > (such as Perl + DBI) and the server sends a two byte command for > > > ROLLBACK instead of sending the string. Further, the two byte command > > > does not have to be parsed and executed - so there is a small, but > > > barely measurable, performance benefit to using the $dbh->rollback > > > statement. > > > > Uhh, there is much more difference! > > I can workaround a lot of database problems in the commit/rollback calls > > in my E/SQL code that I could not do unless I would be analyzing every do > > call > > I already got bitten by autocommit (badly; I'm keeping quiet here) - I > already *have* to do a load of analysis and other futzing around with > every statement. Besides, I can't stop userrs from using $dbh->do() > to execute BEGIN WORK, COMMIT WORK or ROLLBACK WORK. Or from > preparing and executing them. True, but at least we can offer a clean and consistent interface, that when used according to the DBI rules offers what it is expected to offer: a stable and reliable interface to the database in question We also cannot stop users from calling external scripts/programs that ruin our dataset or shutdown the database while we are working in it. -- H.Merijn Brand Amsterdam Perl Mongers (http://amsterdam.pm.org/) using Perl 5.6.2, 5.8.0, 5.8.5, & 5.9.2 on HP-UX 10.20, 11.00 & 11.11, AIX 4.3 & 5.2, SuSE 9.1 & 9.2, and Cygwin. http://www.cmve.net/~merijn Smoking perl: http://www.test-smoke.org, perl QA: http://qa.perl.org reports to: [EMAIL PROTECTED], perl-qa@perl.org
