I have decided to use MAX(tablename_index)+1 in advance of inserting the
record, as I want to use as little dbms-specific magic as possible and
this matches as close as I can figure the behavior of _seq in mSQL.
I would be doing the following in the same thread in this order:
$id=SELECT MAX(tablename_index)+1;
INSERT into tablename VALUES($id,...);
Would it be prudent to wrap a rw lock around this?
--
Mark P. Hennessy [EMAIL PROTECTED]
On Wed, 19 Jun 2002, Mark Hennessy wrote:
> Date: Wed, 19 Jun 2002 14:44:49 -0400 (EDT)
> From: Mark Hennessy <[EMAIL PROTECTED]>
> To: Gerald Clark <[EMAIL PROTECTED]>
> Cc: [EMAIL PROTECTED]
> Subject: Re: Migration of a database from mSQL 2.x to MySQL 3.23.51
>
> I don't see how AUTO_INCREMENT preserves its value in the output of a
> mysqldump.
>
> --
> Mark P. Hennessy [EMAIL PROTECTED]
>
> On Wed, 19 Jun 2002, Gerald Clark wrote:
>
> > Date: Wed, 19 Jun 2002 13:33:00 -0500
> > From: Gerald Clark <[EMAIL PROTECTED]>
> > To: Mark Hennessy <[EMAIL PROTECTED]>
> > Cc: [EMAIL PROTECTED]
> > Subject: Re: Migration of a database from mSQL 2.x to MySQL 3.23.51
> >
> > Use AUTO_INCREMENT.
> > Why should there be a problem restoring?
> >
> > Mark Hennessy wrote:
> >
> > >I'm using DBI/DBD with Perl 5.6.1 to send queries to this database.
> > >
> > >I'm a relative newbie to DB design, I have done some basic administration
> > >for clients. I ask:
> > >
> > >1) In the database I plan on migrating, I have a few simple tables which
> > >use "select _seq" to increment the index value for each table as insert
> > >queries are done. I looked at AUTO_INCREMENT in MySQL and couldn't see
> > >how one would restore from backup (backups made by mysqldump) the last
> > >AUTO_INCREMENT value for a table. I am thinking of using:
> > >
> > >select MAX('tablename_index')+1 from tablename
> > >
> > >instead of mucking around with AUTO_INCREMENT. I plan on making an
> > >insert query with the resulting value in the same session in DBI. Is it
> > >likely that I need to worry about locking the table for this process?
> > >
> > >I don't want to even think about backfilling, so MAX+1 seems fine for what
> > >I'm doing.
> > >
> > >If I understand correctly, as the field is designated as an index, MAX for
> > >it is a stored value and thus is selected very quickly.
> > >
> > >2) Are there any known problems in 3.23.51 stable that would muck with
> > >something as simple as described above?
> > >
> > >Any suggestions?
> > >
> > >--
> > > Mark P. Hennessy [EMAIL PROTECTED]
> > >
> >
> >
> >
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