How to verify that a select is using SERIAL consistency

ScyllaDB
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1

If i have a gocql query like

err = tx.session.Query(fmt.Sprintf("select col, ts, val from \"%s\" where key = ? and ts > ? and col = 'w' order by ts asc limit 1", tx.table), key, tx.readTime.UnixNano()).SerialConsistency(tx.serialConsistency).Scan()

but the docs claim:

// SerialConsistency sets the consistency level for the
// serial phase of conditional updates. That consistency can only be
// either SERIAL or LOCAL_SERIAL and if not present, it defaults to
// SERIAL. This option will be ignored for anything else that a
// conditional update/insert.

that sounds to me like they wont bother applying that consistency level to a select (it will be ignored). Is there any way to debug this so I can verify that select used serial consistency, rather than a non paxos consistency?

2

A subsequent question could be: Does using the .SerialConsistency apply to select statements in gocql?

It does not seem like this is simple to verify.

3

You need to set Consistency to SERIAL to run SELECT with SERIAL consistency. You can verify it with LWT metrics in the dashboards and in rest API - specifically, all cas_* metrics will bump once you execute a SELECT with SERIAL consistency, as it runs a full blown Paxos round with EMPTY mutation, so essentially SELECT in SERIAL mode is a write.

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