Feature request: partial index inside unique method

[hanstf]

Environment

Knex version: 0.95.14 Database + version: postgres 12.5 OS: mac

Feature discussion / request

I saw that there is this feature request created #2525 but was closed. I have also checked that this PR #2401 add predicate options only for .index method. As postgres supports the unique partial index, is it possible to add the predicate inside the .unique method too?

[enchorb]

For the time being I have this working using this syntax:

  await knex.schema.raw(
    `CREATE UNIQUE INDEX "unique_partial_idx_userId_deleted" ON "users" ("userId", "deleted") WHERE "deleted" IS NOT TRUE`
  );

I would prefer something like this would work, but it throws an error

    table.index(['userId', 'deleted'], 'idx_userId_deleted', {
      indexType: 'UNIQUE',
      storageEngineIndexType: 'hash', 
      predicate: knex.whereNot('deleted', true)
    });

[mpcarolin]

We have a desire for this too. We have to use knex.raw, and to make a partial index requires basically reimplementing the where functions that knex already has ourselves.