Sparse option breaks db:mongoid:create_indexes on existing collections

[glebtv]

"Index with name: _slugs_1 already exists with different options"

[glebtv]

Maybe it should be configurable?

[digitalplaywright]

Is it possible for you to recreate the index? The reason for the change in the index is described here: #155.

[digitalplaywright]

Any updates on this issue? I would like to make sure we have reasonable migration paths from one version to another, and this was an unfortunate mistake in our previous indexing scheme.

[glebtv]

No, I just pinned mongoid-slug to the old version. Recreating all indexes is not really an option for a large dataset with many collections, since in practice it should be done manually, and since indexes already exist for me, all my records already have slugs so I don't need sparse.

[glebtv]

But yes, I completely agree that for new projects sparse index is a good idea, that's why I think it should be configurable and default to false in current patch version and to true in next minor/major version, if done according to semantic versioning.

[johnnyshields]

@glebtv I think you are referring to unique, not sparse here. Sparse does not enforce any kind of validation.

[johnnyshields]

Ignore the above, I see the issue here.

[dbackeus]

Since _slugs attribute seems to default to an empty array we get the duplicate key error as soon as we create our second record. Sparse will only work if _slugs was not set to begin with if I'm not mistaken.

I'm not sure how anyone can use this gem and have a working setup. Has there been a change in the uniqueness handling in new mongodb versions, did it use to accept multiple documents having empty arrays?

We're using the gem from scratch on a new app so we have no legacy data to worry about.

[manxingxing]

Encounters the same problem as @dbackeus .

Steps to reproduce:

class Article
  include Mongoid::Document
  include Mongoid::Slug
  include Mongoid::Paranoia

  field :url_seg, type: String

  slug :url_seg
end

Article.create_indexes
Article.create
Article.create 
# => E11000 duplicate key error index

Find out a ticket on mongoDB's site: https://jira.mongodb.org/browse/SERVER-3934

[dblock]

Bump @manxingxing @glebtv What do we want to do about this?

[johnnyshields]

@glebtv all you need to do is drop the index which is affected, then recreate specifically that index. (You can do this for a single index without affecting all other indexes.)

[johnnyshields]

Alternatively, you could do the following steps without affecting production:

• Create a duplicate index to your existing one but with a different name: e.g "_slugs_1_copy" (Mongo doesn't allow renaming indexes: https://jira.mongodb.org/browse/SERVER-7337)
• Drop your existing "_slugs_1" index
• Create the new "_slugs_1" index
• Drop the "_slugs_1_copy" index

[johnnyshields]

I think a suitable workaround would be to have an index: false option on the slug that doesn't create the default index. If so, the user is responsible for defining their own.