RE: Issue with Cassandra consistency in results

To: user@cassandra.apache.org Subject: Re: Issue with Cassandra consistency in results Hi This issue used to appear with me . What I figured in my case was 1. I had 3 machines 2. Inserted the data with ONE consistency (i.e there is no guarantee that data was propagated to remaining nodes

Re: Issue with Cassandra consistency in results

Hi This issue used to appear with me . What I figured in my case was 1. I had 3 machines 2. Inserted the data with ONE consistency (i.e there is no guarantee that data was propagated to remaining nodes , cassandra is supposed to take care of that). 3. Later I figured also that one of

Re: Issue with Cassandra consistency in results

The same issue is appearing in CQL Shell as well. 1) Entered into cqlsh 2) SET CONSISTENCY QUORUM; 3) Ran a select * with partition key in where cluase. First result gave 0 records, and Next records gave results. Its really freaking out us at the moment. And nothing in debug.log or system.log.

Re: Issue with Cassandra consistency in results

The prep is needed. If I recall correctly it must remain in cache for the query to complete. I don't have the docs to dig out the yaml parm to adjust query cache. I had run into the problem stress testing a smallish cluster with many queries at once. Do you have a sense of how many distinct

Re: Issue with Cassandra consistency in results

Hi reiydelle, I cannot confirm the range as the volume of data is huge and the query frequency is also high. If the cache is the cause of issue, can we increase cache size or is there solution to avoid dropped prep statements.? Thank You, Regards, Srini On Thu, Mar 16, 2017 at 2:13 PM,

Re: Issue with Cassandra consistency in results

The discard due to oom is causing the zero returned. I would guess a cache miss problem of some sort, but not sure. Are you using row, index, etc. caches? Are you seeing the failed prep statement on random nodes (duh, nodes that have the relevant data ranges)? *...* *Daemeon C.M.

Re: Issue with Cassandra consistency in results

Depends actually, restore just restores what's there, so if only one node had a copy of the data then only one node had a copy of the data meaning quorum will still be wrong sometimes. On Thu, Mar 16, 2017 at 1:53 PM, Arvydas Jonusonis < arvydas.jonuso...@gmail.com> wrote: > If the data was

Re: Issue with Cassandra consistency in results

If the data was written at ONE, consistency is not guaranteed. ..but considering you just restored the cluster, there's a good chance something else is off. On Thu, Mar 16, 2017 at 18:19 srinivasarao daruna wrote: > Want to make read and write QUORUM as well. > > > On

Re: Issue with Cassandra consistency in results

Want to make read and write QUORUM as well. On Mar 16, 2017 1:09 PM, "Ryan Svihla" wrote: Replication factor is 3, and write consistency is ONE and read consistency is QUORUM. That combination is not gonna work well: *Write succeeds to NODE A but fails on node B,C*

Re: Issue with Cassandra consistency in results

Would switching to select partition_key instead of select count(*) help me any way ? I know that, Logically they both are same.. but just asking out of desperation. Is it worth a shot? On Mar 16, 2017 1:09 PM, "Ryan Svihla" wrote: Replication factor is 3, and write

Re: Issue with Cassandra consistency in results

Replication factor is 3, and write consistency is ONE and read consistency is QUORUM. That combination is not gonna work well: *Write succeeds to NODE A but fails on node B,C* *Read goes to NODE B, C* If you can tolerate some temporary inaccuracy you can use QUORUM but may still have

Re: Issue with Cassandra consistency in results

Replication strategy is SimpleReplicationStrategy. Smith is : EC2 snitch. As we deployed cluster on EC2 instances. I was worried that CL=ALL have more read latency and read failures. But won't rule out trying it. Should I switch select count (*) to select partition_key column? Would that be of

Re: Issue with Cassandra consistency in results

What are your replication strategy and snitch settings? Have you tried doing a read at CL=ALL? If it's an actual inconsistency issue (missing data), this should cause the correct results to be returned. You'll need to run a repair to fix the inconsistencies. If all the data is actually there,