Clarify how EF uses indexes (i.e. currently only for update ordering)

I understand that when using migrations, indexes defined in OnModelCreating will be created in the database.

I have an existing database, with indexes already set up, and was wondering if there is a benefit to defining these indexes in my DbContext? Does EFCore use these index definitions to influence how it builds queries, or does defining an existing index have no effect?

Thanks

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#### Document Details

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* ID: f85ea32c-8d23-d61d-6036-cd772e3e95d9
* Version Independent ID: 25dd8ac4-2521-5200-0ddf-63ac8c83787a
* Content: [Indexes - EF Core](https://docs.microsoft.com/en-us/ef/core/modeling/indexes#feedback)
* Content Source: [entity-framework/core/modeling/indexes.md](https://github.com/aspnet/EntityFramework.Docs/blob/master/entity-framework/core/modeling/indexes.md)
* Product: **entity-framework**
* Technology: **entity-framework-core**
* GitHub Login: @rowanmiller
* Microsoft Alias: **divega**