In Go, the idiom commonly used to handle errors by chaining them with other function calls is by assigning the error value to a variable using the short declaration operator within the conditional statement itself. This allows for concise error handling right after the function call.

The scope of a variable declared inside a function in Go is local to that function. It means the variable can only be accessed within the function where it is declared and not outside of it.

The empty interface (interface{}) in Go can be used with both type assertion and type switch. It serves as a versatile container that can hold values of any type. With type assertion, you can extract the underlying concrete type from an empty interface variable. Similarly, type switch allows you to perform different actions based on the concrete type stored in an empty interface variable. This flexibility makes the empty interface a powerful tool for working with unknown types in Go.

To implement database transactions in Go using the database/sql package, you should begin a transaction using db.Begin(), execute multiple SQL statements within the transaction, and commit the transaction using tx.Commit(). Rolling back the transaction in case of errors is crucial to ensure data integrity.

Amazon DynamoDB would be the recommended choice for this scenario. It offers automatic data partitioning, seamless scalability, and built-in high availability features. DynamoDB's managed service model eliminates the operational overhead of managing distributed systems, making it suitable for applications requiring automatic data partitioning and high availability in a distributed environment.

In Go, the 'do-while' loop, known as the 'do' loop, is used to execute a block of code repeatedly based on a condition, but it ensures that the code block is executed at least once, even if the condition is false initially.

The var keyword in Go is used to declare variables whose values can change during the execution of the program. This flexibility allows for dynamic data storage and manipulation.

In Go, the size of the 'int' data type on a 64-bit system is 4 bytes. The size of data types can vary depending on the architecture of the system, but on a 64-bit system, 'int' is typically 4 bytes.

Code coverage primarily provides insights into the extent to which the codebase is covered by tests. It indicates the percentage of lines or branches of code that have been executed during testing. This metric helps assess the thoroughness of testing efforts and can uncover areas of the codebase that lack proper test coverage. While code coverage is valuable, it's important to note that it doesn't necessarily guarantee the absence of bugs, but it does offer a quantitative measure of test effectiveness.

The recommended practice in Go for error handling when a function returns multiple values, including an error, is to check the error value and handle it accordingly. This ensures that errors are not overlooked and appropriate actions can be taken based on the outcome of the function call.