[CASSANDRA-15626] Need microsecond precision for dropped columns so we can avoid timestamp issues

• Type: Improvement
• Status: Resolved
• Priority: Normal
• Resolution: Not A Problem
• Component/s: Local/SSTable
• Platform: All
• Assignee: Unassigned
• Reporter: Ryan Svihla
• Created: 09/Mar/20 14:00
• Updated: 31/Mar/20 08:25
• Resolved: 30/Mar/20 15:11

Description

In CASSANDRA-15557 the fix for the flaky test is reimplementing the logic from CASSANDRA-12997  which was removed as part of CASSANDRA-13426

However, since dropped columns are stored at a millisecond precision instead of a microsecond precision and ClientState.getTimestamp adds microseconds on each call we will lose the precision on save and some writes that should be dropped could reappear.

Note views affected as well
https://github.com/apache/cassandra/blob/cb83fbff479bb90e9abeaade9e0f8843634c974d/src/java/org/apache/cassandra/schema/SchemaKeyspace.java#L712-L716