[mysql-dde] Re: Fw: P/F/U Keys in LDD

  • From: "Fabricio Mota" <fabricio.oliveira@xxxxxxxxxxxxxxxx>
  • To: <mysql-dde@xxxxxxxxxxxxx>
  • Date: Tue, 20 Dec 2005 14:53:44 -0200

Maybe it is important we also get clear what is our objective with these 
proposals.

Our objective is, during insert/update/delete commands:

minimize:
- internal communication occurrences (internal requests between servers);
- amount of auxiliar data (data used to maintain the DDE internal 
structures, such as indexes, statistic tables, etc);
- response time (for client requests);

and maximize:
- consistence (state that may considered safe and coherent, such as GI 
always correctly replied among all servers);
- integrity (user data will correspond to what he specified to be);
- reliability (continuity of initialized operations, although in presence of 
faults);
- availability (ability to provide service, although in presence of faults);
- Scalability (keep the problems, assigned to number of servers of system - 
such as time response, data size, etc - growing with a rate compatible with 
system growing).
- Transparence (keep the user have the feeling of to access a DDE cluster 
quite as he is accessing a centralized server instance, avoiding, the most 
as we can, to force user to take modifications to their applications and 
database structures intending to solve internal DDE problems Ex.: force user 
to include LOCAL column in all their unique keys, etc.).

I just don't know what these topics are prioritary.

What is the ideal solution:

- no internal communication ocurrences;
- no auxiliar data being needed;
- immediate response time;
- every structures consistent with all servers all the time;
- user data will never be violated but only by his desire;
- Every operation is always correctly finished still in presence of faults;
- Every service is available still in presence of faults);
- the measures assigned to problems growns, at most, proportionally with the 
growing of number of servers.
- The user will never need to perform any undesired change to his commands 
or structures to satisfy to DDE internal conditions.

I think we already know the ideal situation is impossible! Now, lets know 
how we will handle these values to perform the otimal solution!

FM 

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