Golang cassandra gocql transaction need a delay time to executed

Question

This block of code does not delete the data, I don't know why.

s.Query(
        "INSERT INTO smth (id, name) VALUES (?,?)",
        data.ID
        data.Name
    ).ScanCAS(nil, nil, nil)

s.Query(
    "DELETE FROM smth WHERE id = ? AND name = ?",
    data.ID
    data.Name
).Exec()

but if I added some delay like so:

s.Query(
        "INSERT INTO smth (id, name) VALUES (?,?)",
        data.ID
        data.Name
    ).ScanCAS(nil, nil, nil)

time.Sleep(time.Second)
s.Query(
    "DELETE FROM smth WHERE id = ? AND name = ?",
    data.ID
    data.Name
).Exec()

The data will be deleted.

Does anyone know how to fix it without adding the delay? I'm using github.com/gocql/gocql

score 1 · Accepted Answer · answered Jul 18 '22 at 01:44

Gocql queries are executed asynchronously so there are no guarantees that your DELETE is executed after the INSERT.

In any case, your test case is invalid because immediately deleting a partition after it has just been inserted isn't a valid use case.

As a side note, your code appears to be wrong to me. You are calling Query.ScanCAS() when you insert data but the query isn't a lightweight transaction -- it's missing the conditional IF EXISTS/IF NOT EXISTS. Cheers!

Golang cassandra gocql transaction need a delay time to executed

1 Answers1