About [[Wikia:Lookupcontribswikidbname/en]]
DB is useless abbreviation imho.
"DB" was used instead of "database" in the default EN message because it is used in a column meant to take up 3% of a table. As such, the abbreviation of "DB" was helpful to prevent word wrapping issues.
We have hidden the column from the current table display because the field in general was redundant with URL and Title giving necessary information. We may fully remove that column (and that message) as part of our next review of UI design for tools & tables. However, we may also resurface the field if necessary, so I am keeping the message in the i18n file for now.
In the interim, feel free to use the full word for "database" or abbreviate, depending on what makes sense in your local language.
This is a bad practice. See mw:I18n#Messages_are_usually_longer_than_you_think.21