Specify collation on columns

[arrkaye]

Hi,

This has been raised before and closed, but I would like to emphasis how useful it is.

I want to be able to specify the collation on a column, perhaps through an annotation and have EF Core respect and generate the column as such in the migration.

I have temporarily worked around this by adding some SQL to ALTER the column manually in the migration, but this is a slightly tenuous solution as any subsequent ALTER on the column will reset it back to default.

I posit that setting a column as case-sensitive in the DB is a usual and valid use-case and ideally would like it to be supported in EFCore.

Thank you for considering it.

Ark

[ajcvickers]

@arrkaye Can you point to where this was closed before?

[roji]

Duplicate of #19275?

[ajcvickers]

@roji This is 19275. :-)

[roji]

Oops, I was referring to #6577 but on second look, that issue is about specifying collation (and other things) on the database at creation time, rather than as on the column here. So not at a dup..

[ajcvickers]

@roji Agreed, but my conclusion from thinking about this last night, backed up by the discussions on the other issue today, is that we need to take a holistic approach to collations.

Ideally we should be able to run efficient queries when the collation and query are compatible, and throw good, provider-specific exception messages for other cases indicating how to get to efficient queries for other cases.

I'll pull some issues out of the milestone and we'll discuss with the team on Friday.

You already did!

[smitpatel]

EF.Collate!

[roji]

EF.Collate!

Thinking about this in general, per-operation collation support (as opposed to column/database collation settings) is a bit scary... Assuming we add this to SqlBinaryExpression (in the extreme case we can make SqlExpression IAnnotatable 😨), preserving these across all transformations is not going to be easy, can see lots of bugs coming.

[smitpatel]

EF.Collate is quite similar to EF.StoreType.

[roji]

Right, but we already have type mapping on SqlExpression, and a whole inference infrastructure for composing expressions with regards to type mapping... But if you think this is simple 😃

[smitpatel]

I am not saying it is simple but we would need to do it regardless ;)

[roji]

Then possibly related: #6717 (comment)