[CASSANDRA-11432] Counter values become under-counted when running repair.

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Won't Fix
• Severity: Normal
• Since Version: 2.2.5
• Assignee: Aleksey Yeschenko
• Reporter: Dikang Gu

Authors

Aleksey Yeschenko

• Created: 25/Mar/16 05:28
• Updated: 16/Apr/19 09:30
• Resolved: 10/May/16 17:05

Description

We are experimenting Counters in Cassandra 2.2.5. Our setup is that we have 6 nodes, across three different regions, and in each region, the replication factor is 2. Basically, each nodes holds a full copy of the data.

We are writing to cluster with CL = 2, and reading with CL = 1.

When are doing 30k/s counter increment/decrement per node, and at the meanwhile, we are double writing to our mysql tier, so that we can measure the accuracy of C* counter, compared to mysql.

The experiment result was great at the beginning, the counter value in C* and mysql are very close. The difference is less than 0.1%.

But when we start to run the repair on one node, the counter value in C* become much less than the value in mysql, the difference becomes larger than 1%.

My question is that is it a known problem that the counter value will become under-counted if repair is running? Should we avoid running repair for counter tables?

Thanks.

Issue Links

• is related to: CASSANDRA-10862 LCS repair: compact tables before making available in L0
• is related to: CASSANDRA-9811 Tie counter shards' logical clock value to timestamps