Can you find a specific documents position in a sorted Azure Search index

Question

We have several Azure Search indexes that use a Cosmos DB collection of 25K documents as a source and each index has a large number of document properties that can be used for sorting and filtering.

We have a requirement to allow users to sort and filter the documents and then search and jump to a specific documents page in the paginated result set.

Is it possible to query an Azure Search index with sorting and filtering and get the position/rank of a specific document id from the result set? Would I need to look at an alternative option? I believe there could be a way of doing this with a SQL back-end but obviously that would be a major undertaking to implement.

I've yet to find a way of doing this other than writing a query to paginate through until I find the required document which would be a relatively expensive and possibly slow task in terms of processing on the server.

Answer 1

There is no mechanism in Azure Search for filtering within the resultset of another query. You'd have to page through results, looking for the document ID on the client side. If your queries aren't very selective and produce many pages of results, this can be slow as $skip actually re-evaluates all results up to the page you specify.

You could use caching to make this faster. At least one Azure Search customer is using Redis to cache search results. If your queries are selective enough, you could even cache the results in memory so you'd only pay the cost of paging once.

Answer 2

Trying this at the moment. I'm using a two step process:

1. Generate your query but set $count=true and $top=0. The query result should contain a field named @odata.count.
2. You can then pick an index, then use $top=1 and $skip=<index> to return a single entry. There is one caveat: $skip will only accept numbers less than 100000