Elastic search sort script not working after upgrade

Question

The following sort script used to work in 0.2 but now fails in 0.9:

{
  "_script": {
    "script": "org.elasticsearch.common.Digest.md5Hex(doc['myId'].value + 12345)",
    "type": "string",
    "order": "asc"
  }
}

The error I am receiving is:

PropertyAccessException[[Error: unresolvable property or identifier: org]

I have seen posts suggesting creating a custom score query that does this work, so a little extra information. I am already using a custom score query, and this sort is a secondary sort for when scores match, which can (and should) happen regularly. The constant number in the example above is based on the person performing the search so each person who searches gets a randomized but consistent sorting and we don't always show the same results at the top to everyone.

I cannot find any information on why this is happening and how to go about fixing it while retaining the same sorting functionality. Any help or pointing me in a new direction would be greatly appreciated.

Answer 1

I replied to your post in the mailing list, the problem is due to the fact that the org.elasticsearch.common.Digesthas been removed from elasticsearch. I don't think you can replace it with a single line, probably easier to write a Java native script if you are familiar with Java.

On the other hand I see you have some more details in your question here, and I've been wondering whether you could even avoid using script sorting to achieve what you want.

Your usecase makes me think about the recently added rescore query, which allows to rescore top K results using a secondary query. Do take into account that the rescore is executed on each shard. So if you ask for the first 10 documents, the rescore will happen on the top 10 documents per shard, and that will influence the top 10 documents that get selected during the reduce phase. Sounds like you were more looking for changing the order of the documents that get returned, while with the rescore query those documents might change due to the rescore process itself.

The coming version, 0.90.4, will also contain random seeded ordering, which should help you with the random aspect of your sorting. Have a look at the related issue to know more.

Would be cool to combine a rescore query with a function score query that allows for random ordering.