Indices on Single Column Expressions

Problem

Commonly we define indices (and unique indices) that make use of expressions, most commonly LOWER(col) and UPPER(col), though we are unable to express that in our schema.prisma. Furthermore prisma actually tries to remove our indices containing expressions in every subsequent migration, causing us to manually update each migration (looks like this is already captured in https://github.com/prisma/prisma/issues/12914).

Edit: As of prisma 4.1, prisma migrate dev no longer attempts to remove the existing index on those columns, but still tries to add the new index. This causes the newly added migration to fail.

An isolated reproducible example of this can be found here.

Suggested solution

model User {
  id        String @id
  firstName String @map("first_name")

  @@index([@lower(firstName)])
  @@map("users")
}

to generate

CREATE INDEX "user_first_name_idx" ON "user"(LOWER("first_name"));

Ideally the solution would be able to be applied to multi column indices the same as single column indices

@@index([@lower(firstName), @lower(lastName)])

as well as unique indices.

@@unique([@lower(firstName), @lower(lastName)])

Alternatives

Adding a standard index @@index([firstName]) and then manually updating the generated migration to use an expression on the desired columns.

[janpio]

Let’s close this then, and you make sure that the missing bits are mentioend over there via a comment please.

duplicate of https://github.com/prisma/prisma/issues/2504

[drewcorlin1]

When attempting to update to prisma 4.1 I followed the upgrade guide and ran prisma db pull. It attempted to delete my functional index from my prisma schema.

If I add that index back to my schema and then run prisma migrate dev it now doesn’t attempt to delete the functional index, but does attempt to add a new one which fails. This is preventing me from upgrading to prisma 4.x

With the new @@index([created_at(sort: Desc)]) syntax being added. Maybe something like @@index([author, name(lower: true)]) could make sense for this feature request?