What levels of transaction isolation have you set manually in practice?

In practice with databases in Go, it is often necessary to manually set transaction isolation levels to control concurrency and prevent issues with simultaneous access. The main isolation levels I have used:

• Read Uncommitted — the lowest level, allows reading uncommitted changes, which can lead to "dirty" reads.
• Read Committed — prevents reading uncommitted data but allows non-repeatable reads.
• Repeatable Read — guarantees that data read in a transaction will not change until it completes.
• Serializable — the strictest level, provides full transaction isolation as if transactions were executed sequentially.

In Go, using the database/sql package, the isolation level can be set via the BeginTx method with the sql.TxOptions{Isolation: sql.LevelSerializable} parameter, for example:

ctx := context.Background()
tx, err := db.BeginTx(ctx, &sql.TxOptions{Isolation: sql.LevelRepeatableRead})
if err != nil {
    // handle error
}
// work with the transaction