NuGet "filter=(tolower(Id))" queries don't use a database index in Nexus 2.x, causing severe performance issues in large instances

Nexus 2.14.4 has experienced some severe performance problems with certain NuGet builds. Queries issued sporadically slow down, and they frequently get complete failures due to the h2 connection pool being exhausted.

They have builds that are making large numbers of queries like this:

[10/Aug/2017:20:18:02 +0100] "GET /nexus/service/local/nuget/nuget-repo-read/Packages?$filter=(tolower(Id)%20eq%20'akka.remote')%20and%20(Version%20eq%20'1.1.3') HTTP/1.1" 200 5425 12242

Investigation has shown the cause was queries with a e.g. "((LOWER(ID) = 'nunit')" in them. It turns out these will not use the index, and will result in a full table scan being done.

 Acceptance

• Queries with a "LOWER" will use the index