Getting extra results in content search result with Azure Search

Question

Using Azure search in Sitecore 9.1.1. We are getting extra results in Azure search only, with Solr results are showing correctly.

Scenario:

Fetching result from the below structure :

When we try to fetch result by passing 1999 in Azure search then it shows result for Data 1999 folder as well. If we pass 1998 then result shows for 1998 only, it also works when we pass Data 1999. Issue is with 1999 only, getting these results while passing 1999 in Azure search:

Test 1
Test 2
Test 3

Instead of

Test 1
Test 2

Using code :

predicate = predicate.And(x => x.Year.Equals(Year));

Answer 1

I had a bit same case in my project. When I investigated how Azure Search works underhood I found that string types all times converted to Contains query in Azure Search. You can see that if taking a look into Search.log for your environment.

The same issue with the StartsWith() function and etc. check this link:

In your case I see some scenarios to resolving this issue:

1. Make a computed field/change type of field year on any numeric type. That can be int. (Equals for numeric types works well)
2. Switch to Solr (it will take 1-day max but will save a lot of time with Search work). Anyway, the azure search will be deprecated in the next version of Sitecore. Check this link.
3. Use straight requests to Azure Search instead of Sitecore LINQ provider. There exists an Equals function that can be used. (take a lot of time for rewriting and hard to support solution like this)
4. Take a look at the Wildcard() LINQ function that allows using Search Engine syntaxis for field requests. Probably it will help too.

My experience with Azure Search was a nightmare till we didn't switch to Solr Engine in all environments and removed Azure-related things from a project (before we had Azure Search for production and Solr for development). Because they're a lot of limitations.