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From:Martijn Tonies Date:May 26 2005 6:26am
Subject:Re: InnoDB to MyISAM
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> >> >>key relationships?
> >> >
> >> > MyISAM can't FK's.
> >>
> >> Yes it can, they're just not enforced.
> >
> > LOL - that's just like saying that MyISAM supports transactions
> > if you only do transactions that are a single statement...
> >
> > In other words: useles.
> Somehow I use these "useles" foreign keys to create relational databases.
> A foreign key is merely a column which references a primary key or a
> key in the same or another table.
> I think you're confusing referential constraints with foreign keys.

In my book, referential constraints and foreign key constraints (the full
are the same.

> Even in
> database systems that support referential constraints and cascade
> dependencies, the usage of such constraints on foreign keys is optional
> dependant on your desire to trade-off referential integrity for
> In some systems, the performance penalty of enforcing referential
> constraints and doing deletions in dependant tables simply cannot be
> afforded during high usage hours for databases that serve real-time
> (I work in telecom for example), and therefore one may choose to implement
> cleanup process during very low usage hours in the middle of the night to
> find orphaned records, delete them, and then optimize the table.  This
> allows you to avoid deleting anything but the primary record while people
> are waiting on the phone, which for MyISAM has the added benefit of
> concurrent insert/select to continue in the dependent tables.

I'm not going to do a serious answer on this one if this is really what
you're doing.

With regards,

Martijn Tonies
Database Workbench - tool for InterBase, Firebird, MySQL, Oracle & MS SQL
Upscene Productions

InnoDB to MyISAMScott Purcell25 May
  • Re: InnoDB to MyISAMDBA)25 May
  • Re: InnoDB to MyISAMRafal Kedziorski25 May
  • Re: InnoDB to MyISAMJeremiah Gowdy25 May
  • Re: InnoDB to MyISAMMartijn Tonies25 May
  • Re: InnoDB to MyISAMJeremiah Gowdy26 May
    • Re: InnoDB to MyISAMmfatene26 May
  • Re: InnoDB to MyISAMMartijn Tonies26 May
  • Re: InnoDB to MyISAMJeremiah Gowdy26 May
  • Re: InnoDB to MyISAMJeremiah Gowdy26 May
  • Re: InnoDB to MyISAMMartijn Tonies26 May
    • RE: InnoDB to MyISAMPeter Normann26 May
  • Re: InnoDB to MyISAMJeremiah Gowdy27 May
Re: InnoDB to MyISAMMartijn Tonies26 May
Re: InnoDB to MyISAMDBA)26 May