[CASSANDRA-8051] Add SERIAL and LOCAL_SERIAL consistency levels to cqlsh

• Type: Bug
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 2.0.15, 2.1.6
• Component/s: Feature/Lightweight Transactions, Legacy/Tools
• Labels: LWT cqlsh
• Severity: Low
• Assignee: Carl Yeksigian
• Reporter: Nicolas Favre-Felix

Authors

Carl Yeksigian

Reviewers

Stefania Alborghetti

• Created: 03/Oct/14 17:27
• Updated: 25/Oct/19 13:11
• Resolved: 05/May/15 19:47

Description

cqlsh does not support setting the serial consistency level. The default CL.SERIAL does not let users safely execute LWT alongside an app that runs at LOCAL_SERIAL, and can prevent any LWT from running when a DC is down (e.g. with 2 DCs, RF=3 in each.)

Implementing this well is a bit tricky. A user setting the serial CL will probably not want all of their statements to have a serial CL attached, but only the conditional updates. At the same time it would be useful to support serial reads. "WITH CONSISTENCY LEVEL" used to provide this flexibility.

I believe that it is currently impossible to run a SELECT at SERIAL or LOCAL_SERIAL; the only workaround seems to be to run a conditional update with a predicate that always resolves to False, and to rely on the CAS response to read the data.