[Opensim-dev] users and agents table, and other oddities?

[Sean Dague]

On Sun, Oct 14, 2007 at 09:30:39AM +0200, Tleiades wrote:
> Hi
> 
> I am a little mystified about the users table and the agents table.
> 
> I am afraid this boils down to definitions of:
> 
> What is a user?, What is an agent? and what is an avatar?, well mostly the 
> difference between a user and an agent.
> 
> In the SQLite implementation both tables are maintained, in the MySQL 
> implementation, only the user table is maintained.

Actually, the agents table is only maintained in memory, it is never
written back to disk.  This is effectively the same behavior as the
mysql approach.

> According to the defintions of user vs agent in UserProfileData.cs the UUID 
> of UserAgentData is not the same as the UUID of UserProfileData, but if this 
> is so, how do you relate an agent to a user? the SQLite implementation, 
> violates the comment made in the cs code, and assigns the same value to both 
> UUID of agents and users.
> 
> <rant>
> who on earth, has decided that the datatype (UUID) is a propper name for a 
> column in a database or a property on a class? UserID of type UUID, and 
> AgentID of type UUID would be more fitting, or perhaps just ID of type UUID 
> (depending on temperament)
> </rant>

.ID is probably the best thing.  What it is the idea for should be
evident based on the object it is attached to.


> 
> So I guess my primary question regarding agents and users is?
> What is the difference? and do we need to distinguish between the two?
> 
> now on to regions..
> First some definitions.
> a regionhandle, identifies a region based on it's x,y position in the grid, 
> which is combined into one integer value.
> a regionid, identifies a region based on a UUID.
> 
> Regions have the regionid as the primary key, in both SQLite and MySQL. In 
> the agents table we store both the handle and the id , in the users table we 
> store the handle but not the id.

IMHO, We should stop storing handle, and should construct it when we
need it (as it is 100% computable from region location).  Having
multiple things that behave like keys in the objects continues to ask
for trouble.

> This gives rise to the question.. "Is the users home" tied to the handle or 
> the id. What is really the primary id of a region, the handle or the
> id?

My vote is for ID.

	-Sean

-- 
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Sean Dague                                       Mid-Hudson Valley
sean at dague dot net                            Linux Users Group
http://dague.net                                 http://mhvlug.org

There is no silver bullet.  Plus, werewolves make better neighbors
than zombies, and they tend to keep the vampire population down.
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