What level of insulation was used in the project?

The transaction isolation level determines how isolated the operations of one transaction are from those of others. In Go projects working with databases, the isolation level is usually chosen based on the requirements for consistency and performance.

The most commonly used levels are:

• Read Committed — the transaction only sees committed data, preventing dirty reads.
• Repeatable Read — guarantees that data read in a transaction will not change until it completes, preventing non-repeatable reads.
• Serializable — the strictest level, providing full isolation but reducing performance.

In my projects, I usually used the Read Committed or Repeatable Read levels to balance between consistency and performance. For example, for financial operations, Serializable was chosen to exclude any anomalies.

In Go, the isolation level can be set through the database driver, for example, when using database/sql with PostgreSQL:

_, err := db.Exec("SET TRANSACTION ISOLATION LEVEL REPEATABLE READ")
// then start the transaction

Or when creating a transaction:

trx, err := db.BeginTx(ctx, &sql.TxOptions{
    Isolation: sql.LevelRepeatableRead,
})

The choice of the isolation level depends on the specific project requirements and the trade-off between data integrity and performance.