Have you worked with transactions in Postgres and what levels of isolation have you encountered?

In Postgres, I worked with transactions using standard SQL commands BEGIN, COMMIT, and ROLLBACK, as well as through drivers in Go, such as database/sql.

Regarding isolation levels, Postgres supports four main levels:

• Read Uncommitted (effectively works as Read Committed, since Postgres does not allow dirty reads)
• Read Committed (default level) — a transaction sees only committed data at the start of each read operation
• Repeatable Read — guarantees that all reads within a transaction will see the same snapshot of data, preventing non-repeatable reads
• Serializable — the strictest level, providing full transaction isolation as if transactions were executed sequentially

In Go, you can set the isolation level using the TxOptions method when beginning a transaction:

opts := &sql.TxOptions{
    Isolation: sql.LevelSerializable,
}
tx, err := db.BeginTx(ctx, opts)

I used different levels depending on the requirements for consistency and performance.