[SQL] `psc.Alias` length and uniqueness

[MaximeBICMTL]

Description

In the LORIS SQL schema, psc.Alias is 3-character long with no constraint of uniqueness. I think we should make this field 4-character (maybe 5?) long and unique.

The arguments are the following one:

• 3 characters is rather limiting, psc.Alias is 4-character long in C-BIG (the field is overwritten).
• The psc.MRI_alias field, which we would like to eventually remove, is also 4-character long.
• I think some code in LORIS-MRI relies on the uniqueness of site aliases, and I would not be surprised if this also happens in other code.

There are duplicates in C-BIG but I believe this is a mistake on our part. What about other projects ?

[MaximeBICMTL]

Pinging @ridz1208 since this is relevant to C-BIG.

[ridz1208]

No oppositions for making it 4 characters

As for uniqueness, I don't think it's an issue now

FYI, the repetition on CBIG is not accidental. On older LORIS versions we could not generate PSCIDs based on Project, it was only site based, so we mimiced that by making all sites of a certain project have the same Alias so the PSCID would reflect the project basically. Going forward we could if we want to make it unique but personally I don't see the use, just my opinion, there could be a situation where multiple sites use the same alias....