Redis offers an "Eviction Policy" feature that allows for the creation of data structures with a predefined maximum capacity. This policy determines how Redis handles data when the memory limit is reached.

In Go, the complex128 data type is used to store complex numbers. The complex128 type represents complex numbers with float64 real and imaginary parts, offering higher precision compared to complex64, which uses float32 parts.

In Go, interface{} is known as the empty interface and it can hold any type, whereas an empty interface{} can hold any type as well but with a distinction that it can't hold any value (except nil). Understanding this subtle difference is crucial in Go programming.

A type switch in Go enables you to check the type of an interface value against multiple types. This is particularly useful when dealing with interface values of unknown types, as it allows you to handle each type differently within the switch block.

Couchbase would be the most suitable choice in this scenario. It offers a flexible schema design with support for JSON documents, allowing developers to adapt the data model as needed without rigid schema constraints. Couchbase also provides seamless scalability through its distributed architecture and built-in caching capabilities, making it easy to scale both vertically and horizontally as application requirements evolve.

ORM libraries in Go typically handle database CRUD (Create, Read, Update, Delete) operations automatically. Developers define Go struct types that map to database tables, and the ORM library abstracts away the SQL queries required for CRUD operations, allowing developers to work with Go objects directly.

The go test command in Go is specifically designed for running tests and benchmarks within the current package. It automatically identifies test files and executes the test cases defined in them.

The correct syntax for a type switch statement in Go is switch x.(type) { case Type1: // code case Type2: // code default: // code }. Type switches in Go allow you to perform different actions based on the type of an interface variable. It evaluates the type of x and compares it with each case. If a match is found, the corresponding code block is executed. If none of the cases match, the default case (if provided) is executed.

In Go unit testing, the FailNow function is used to indicate a failed test and stop execution immediately. It marks the test as failed and terminates the test execution, preventing further test cases from running.

Type assertion in Go is primarily used to test whether an interface value holds a specific type and to extract the underlying concrete value of that type if it does. This allows Go programmers to work with the concrete type safely within the scope of the assertion.

No, structs cannot have circular references in Go. Unlike some other languages, Go does not allow self-referencing or circular structures directly in structs.

In Go, a struct can have pointer methods associated with it. Pointer methods are functions that have a receiver of a pointer type. They allow modifying the state of the struct instance directly, which is particularly useful when working with large struct types or when mutations need to be reflected outside of the method scope.