OT: (Way OT) PHP and MySQL concurrency control using MyISAM
pcloches at gmail.com
Sun Mar 23 17:01:03 PDT 2008
MyISAM supports locking (like all engines) but not transactions. Without
transactions, you can do a lock lock a table or tables, and unlock them,
however you cannot roll back statements -- so if a statement down the line
fails for some reason there is no way to rollback and undo past statements
(automagically at least)
The simple solution is to use InnoDB, which supports Good Things you want -
it's more scalable across multiple threads, row-level locking, transactions,
foreign keys, etc.
The differences are fairly well documented. It sounds like you're using PDO,
please read up on auto-commit mode. Don't reinvent the wheel, especially
when the wheel is already built better than you could hack out a replacement
for it :)
On 23/03/2008, Da Rock <rock_on_the_web at comcen.com.au> wrote:
> On Sun, 2008-03-23 at 19:17 -0400, Bill Moran wrote:
> > Da Rock <rock_on_the_web at comcen.com.au> wrote:
> > >
> > > I know this is not quite the list for these things, but I tried the
> > > list and got no reply whatsoever. In fact, I don't think anyone's home
> > > cause the entire list is silent...
> > >
> > > I'm trying to setup a system using web apps in PHP using MySQL as the
> > > backend database, only this time I need transaction services.
> > > to the PHP manual if a transaction is served for MySQL it can come
> > > as committed even though it may not. So what I'm trying to accomplish
> > > develop some row level locking with the PHP script.
> > >
> > > I enquired about setting up a servlet (for want of a better term) with
> > > PHP, something that will serve the requests of the rest of the app. To
> > > be honest though, I'm not entirely sure how to approach this.
> > Wow. That's one crazy attempt at a workaround.
> > The correct solution is to use the correct tool for the job. Either
> > install PostgreSQL and use it instead, or use InnoDB tables.
> Actually, I think I may have got some facts confused here- I thought
> that MyISAM was not supposed to be transaction supported, but according
> to most stuff I've read it supports table level transaction locking.
> And the PHP manual says it will only come back with a false commit IF
> the table DOESN'T support transactions at all.
> So what is the truth here? If MyISAM supports transaction table locking
> I may be ok here- and save myself a hell of a lot of trouble to boot.
> Thanks guys, again.
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