option to sort by other fields

[mschoch]

Sometimes its useful for applications to want the search results sorted by another field, often a date or numeric value.

[AndrewVos]

I wanted to do a spike and see if bleve will work for my client, but they definitely need sorting.

At the moment they're only really sorting on "price", which is a float.

[mschoch]

Some interesting bits about how this is done in Lucene: http://blog.trifork.com/2011/10/27/introducing-lucene-index-doc-values/

[dorsha]

We would love to have sort functionality on other fields as well (for pagination and etc.)

[meirwah]

pagination without sorting is a bit lacking.. is this feature planned anytime soon?

[mschoch]

No one is currently working on it. At the moment I'm focused exclusively on performance, as for our use case sorting/pagination by score is sufficient, but indexing throughput is too low to be usable.

Its not a small job, but its not impossible for someone else to take a look at it in parallel. There are two main pieces.

1. A new implementation of the Collector interface, which is responsible for looking at all the scored "hits" and deciding which ones to keep and return to the user. The current impl looks at score and keeps the top N, after skipping over M hits. The new impl would look at the "sort" field(s), and keep the highest/lowest results, possibly also breaking ties by using the score.
2. Part 1 sounds straightforward, but the missing piece is how does it access the value for the sort field(s). Probably some interfaces need to change to accommodate this, as when users request stored fields we don't load them till later in the process. Some thought needs to be put into the most efficient way to collect these sort values while we execute the search.

[slavikm]

@mschoch is anyone working on this currently? I would like to take a stub at this as we need sort for other fields.

[caseymrm]

@slavikm I saw you had one collector commit, is this something you're actively working on?

[slavikm]

@caseymrm I started, then had to stop for a while (other stuff came up) and now I'm getting back to it. Hopefully will try and commit something next week.

[nadoo]

really need this feature, hope it will be implemented soon. thank you! @slavikm .

[yonderblue]

👍 as a need to be able to use the lib

[mschoch]

Yes, I understand this is important. We will prioritize this and make sure we at least get the API to do this into 1.0.

[yonderblue]

I love to see the work here! :D