constraint that there is only one prefix set to active

[sjib]

To not corrupt generate_oid we should add a constraint or conditiion that checks whether more than one prefix is set to active. I don't know yet how to formulate that - but maybe the best way is that you have to set all to inactive before you can set another one to active.

[sjib]

Ideas for implementation:

create unique index on tww_sys.oid_prefixes(active) 
where active = true;

https://stackoverflow.com/questions/28166915/postgresql-constraint-only-one-row-can-have-flag-set

[sjib]

@cymed @ponceta What do you think? Any other ideas or thoughts?

[cymed]

I deem it smarter to keep it as is and allow multitenancy in a second step

[sjib]

When would you want to have several prefixes active at the same time?
May be we need to discuss and collect some use cases here first and give this to the user group.

[cymed]

When you want to allow multitenancy (i.e. to store all cadastres on one database), you need to alter the system with which you choose the prefix

[ponceta]

As I remember from a past discussion, we would want an option on the plugin to select and change the oidprefix on the fly. It would actually be possible but for one user only, as soon as multiple users would edit data simultaneously it would fail since the setting is yet in the database.

• What happens on the new 2020 model?

If provider A defines dataset for infrastructure maintener B.
Entities will be tagged with default fk_provider and fk_dataowner data and prefixed with the dataowner oid or provider oid?

• What are oid prefixes for if we constraint our users to set fk_provider and fk_dataowner?

[cymed]

1. We do not constraint our users to set fk_provider and fk_dataowner, we only give them an option to set their own default on the db side.
2. I would strongly discourage to define the default dataowner and provider in the plugin. When working with multiple databases, it is common to copy-paste the qgis project and alter the pg service name. It is safer to define the default per database or (once we support multitenancy) to define it per tenant