Ok, Shawn, I agree.
But as I've noticed, the tables used in database MySQL seems to be of MyISAM
type. So, I don't know if is a good idea to modify the MyISAM engine only
for that.
Do you think could it be a good idea to develop another specific engine only
for managing this three tables?
Or do you think it could be better to increment the SQL92 language with
specific commands for DDE management? Such as
create dde_group my_dde_group;
drop dde_group my_dde_group;
create dde_server 'mysql://server1.mysql.com:3306' as 1;
drop dde_server 1;
subscribe database Database1 from dde_server 1 into my_dde_group;
unsubscribe database Database1 from dde_server 1 from my_dde_group;
And query their data as a virtual table, or a view.
Tell me your opinion
Fabricio
-----Mensagem original-----
De: SGreen@stripped [mailto:SGreen@stripped]
Enviada em: sabado, 12 de novembro de 2005 15:47
Para: Fabricio Mota
Cc: internals@stripped; Sanja Byelkin
Assunto: Re: RES: RES: System Tables
"Fabricio Mota" <fabricio.mota@stripped> wrote on 11/12/2005 09:46:07 AM:
> Hi Sanja,
>
> My idea is to perform a distributed data system (DDS) to this engine. A
DDS
> will be composed by at least one group. Each group may involve many
MySQL
> servers, and each server may belong to more than one group.
>
> So, the best way I've seen is to manage it into 3 system tables:
DDE_SERVER,
> DDE_GROUP and DDE_SERVER_GROUP.
> For example: to subscribe a server into a group, I must: a) insert the
> server into DDE_SERVER table, if not exists; b) insert a relation
between
> the new server and the existent group in DDE_SERVER_GROUP. So, all the
group
> multicast communication will be proceeded to synchronize all servers.
>
> Sanja, may I send the doc spec to you? (it's better shown in page 11).
>
> Thank you again
>
> Fabricio
>
> -----Mensagem original-----
> De: Sanja Byelkin [mailto:sanja@stripped]
> Enviada em: sabado, 12 de novembro de 2005 07:09
> Para: Fabricio Mota
> Cc: internals@stripped
> Assunto: Re: RES: System Tables
>
>
> Hi, Fabricio!
>
> On Fri, Nov 11, 2005 at 11:13:45PM -0300, Fabricio Mota wrote:
> > Ok, I'll study these codes.
> >
> > But I need to create 3 system tables in mysql database. These tables
> should
> > manage persistent data, and make specific actions (specific code
routines)
> > when user try to insert, update or delete data into or from them. Do
you
> > think these codes you adviced me could answer these (new) questions?
>
> I am not sure that it is right decision to add something to mysql
> database. If you describe why you need that tables in mysql maybe I Will
> agree with you, but now I have bad strong feeling about adding
> something to mysql database.
>
> To perform some actions on changing some special tables you have 2
> options:
> 1) use triggers.
> 2) prohibit access direct access to that tables and use special
> commands to update them (like CREATE/DROP PROCEDURE)
>
> [skip]
>
> --
> __ ___ ___ ____ __
> / |/ /_ __/ __/ __ \/ / Mr. Oleksandr Byelkin <sanja@stripped>
> / /|_/ / // /\ \/ /_/ / /__ MySQL AB, Full-Time Developer
> /_/ /_/\_, /___/\___\_\___/ Lugansk, Ukraine
> <___/ www.mysql.com
>
>
The way the MySQL product is designed, everyhing specific to a method of
managing tables is to be managed within that particular "engine". If you
need 3 tables to track who is in a group (etc) then your engine needs to
keep up with that information internal to itself (and isolate the rest of
MySQL from needing to ignore the activity of your engine.)
Those tables in the mysql database are general to ALL of the database
engines (MyISAM, InnoDB, BDB, Archive, Blackhole, etc) While those
structures specific to certain engines (row-level locking and
multi-versioning for InnoDB, data partitioning and two-phase commits for
NDB, etc) are maintained within the engines themselves.
Does that make sense?
Shawn Green
Database Administrator
Unimin Corporation - Spruce Pine
