>Also, our partition keys are not distributed evenly as I had pasted output earlier.
Thanks, I see that now. Can you share the full output of nodetool tablestats and nodetool tablehistograms? Out of curiosity, are you running repairs on this cluster? If so, what type of repairs are you running and how often? One way you might differentiate between a server-side/configuration issue or a client/data model issue is to write a script that populates a test keyspace with uniformly distributed partitions and see if that keyspace also exhibits a similar imbalance of partitions per node. You might be able to use a heavily-throttled cassandra-stress invocation to handle this. On Wed, Jun 20, 2018 at 12:32 PM, learner dba < cassandra...@yahoo.com.invalid> wrote: > > Hi Joshua, > > Okay, that string appears to be a base64-encoded version 4 UUID. > Why not use Cassandra's UUID data type to store that directly rather than > storing the longer base64 string as text? --> It's an old application and > the person who coded it, has left the company. > What does the UUID represent? --> Unique account id. > Is it identifying a unique product, an image, or some other type of > object? --> yes > When and how is the underlying UUID being generated by the application? > --> Not sure about it. > > I assume you're using the default partitioner, but just in case, can you > confirm which partitioner you're using in your cassandra.yaml file (e.g. > Murmer3, Random, ByteOrdered)? --> partitioner: org.apache.cassandra.dht. > Murmur3Partitioner > > > Mentioned Jiras are from much older version than ours "3.11.2"; Also, our > partition keys are not distributed evenly as I had pasted output earlier. > Which means none of the Jiras apply in our case :( > > > On Wednesday, June 20, 2018, 12:18:28 PM EDT, Joshua Galbraith < > jgalbra...@newrelic.com.INVALID> wrote: > > > Okay, that string appears to be a base64-encoded version 4 UUID. Why not > use Cassandra's UUID data type to store that directly rather than storing > the longer base64 string as text? What does the UUID represent? Is it > identifying a unique product, an image, or some other type of object? When > and how is the underlying UUID being generated by the application? > > I assume you're using the default partitioner, but just in case, can you > confirm which partitioner you're using in your cassandra.yaml file (e.g. > Murmer3, Random, ByteOrdered)? > > Also, please have a look at these two issues and verify you're not > experiencing either: > > * https://issues.apache.org/jira/browse/CASSANDRA-7032 > * https://issues.apache.org/jira/browse/CASSANDRA-10430 > > > On Wed, Jun 20, 2018 at 9:59 AM, learner dba <cassandra...@yahoo.com. > invalid> wrote: > > Partition key has value as: > > MWY4MmI0MTQtYTk2YS00YmRjLTkxND MtOWU0MjM1OWU2NzUy other column is blob. > > On Tuesday, June 19, 2018, 6:07:59 PM EDT, Joshua Galbraith < > jgalbra...@newrelic.com. INVALID> wrote: > > > > id text PRIMARY KEY > > What values are written to this id field? Can you give us some examples or > explain the general use case? > > On Tue, Jun 19, 2018 at 1:18 PM, learner dba <cassandra...@yahoo.com. > invalid <cassandra...@yahoo.com.invalid>> wrote: > > Hi Sean, > > Here is create table: > > CREATE TABLE ks.cf ( > > id text PRIMARY KEY, > > accessdata blob > > ) WITH bloom_filter_fp_chance = 0.01 > > AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'} > > AND comment = '' > > AND compaction = {'class': 'org.apache.cassandra.db. compaction. > SizeTieredCompactionStrategy', 'max_threshold': '32', 'min_threshold': '4'} > > AND compression = {'chunk_length_in_kb': '64', 'class': ' > org.apache.cassandra.io. compress.LZ4Compressor'} > > AND crc_check_chance = 1.0 > > AND dclocal_read_repair_chance = 0.1 > > AND default_time_to_live = 0 > > AND gc_grace_seconds = 864000 > > AND max_index_interval = 2048 > > AND memtable_flush_period_in_ms = 0 > > AND min_index_interval = 128 > > AND read_repair_chance = 0.0 > > AND speculative_retry = '99PERCENTILE'; > Nodetool status: > > Datacenter: dc1 > > ======================= > > Status=Up/Down > > |/ State=Normal/Leaving/Joining/ Moving > > -- Address Load Tokens Owns (effective) Host ID > Rack > > UN xxxxx 20.66 GiB 256 61.4% f4f54949-83c9-419b-9a43- > cb630b36d8c2 RAC1 > > UN xxxxx 65.77 GiB 256 59.3% 3db430ae-45ef-4746-a273- > bc1f66ac8981 RAC1 > > UN xxxxxx 60.58 GiB 256 58.4% 1f23e869-1823-4b75-8d3e- > f9b32acba9a6 RAC1 > > UN xxxxx 47.08 GiB 256 57.5% 7aca9a36-823f-4185-be44- > c1464a799084 RAC1 > > UN xxxxx 51.47 GiB 256 63.4% 18cff010-9b83-4cf8-9dc2- > f05ac63df402 RAC1 > > Datacenter: dc2 > > ======================== > > Status=Up/Down > > |/ State=Normal/Leaving/Joining/ Moving > > -- Address Load Tokens Owns (effective) Host ID > Rack > > UN xxxx 24.37 GiB 256 59.5% 1b694180-210a-4b75-8f2a- > 748f4a5b6a3d RAC1 > > UN xxxxx 30.76 GiB 256 56.7% 597bac04-c57a-4487-8924- > 72e171e45514 RAC1 > > UN xxxx 10.73 GiB 256 63.9% 6e7e474e-e292-4433-afd4- > 372d30e0f3e1 RAC1 > > UN xxxxxx 19.77 GiB 256 61.5% 58751418-7b76-40f7-8b8f- > a5bf8fe7d9a2 RAC1 > > UN xxxxx 10.33 GiB 256 58.4% 6d58d006-2095-449c-8c67- > 50e8cbdfe7a7 RAC1 > > > cassandra-rackdc.properties: > > dc=dc1 > rack=RAC1 --> same in all nodes > > cassandra.yaml: > num_tokens: 256 > > endpoint_snitch: GossipingPropertyFileSnitch > I can see cassandra-topology.properties, I believe it shouldn't be there > with GossipPropertyFileSnitch. Can this file be causing any trouble in data > distribution. > > cat /opt/cassandra/conf/cassandra- topology.properties > > # Licensed to the Apache Software Foundation (ASF) under one > > # or more contributor license agreements. See the NOTICE file > > # distributed with this work for additional information > > # regarding copyright ownership. The ASF licenses this file > > # to you under the Apache License, Version 2.0 (the > > # "License"); you may not use this file except in compliance > > # with the License. You may obtain a copy of the License at > > # > > # http://www.apache.org/ licenses/LICENSE-2.0 > <http://www.apache.org/licenses/LICENSE-2.0> > > # > > # Unless required by applicable law or agreed to in writing, software > > # distributed under the License is distributed on an "AS IS" BASIS, > > # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. > > # See the License for the specific language governing permissions and > > # limitations under the License. > > > # Cassandra Node IP=Data Center:Rack > > 192.168.1.100=DC1:RAC1 > > 192.168.2.200=DC2:RAC2 > > > 10.0.0.10=DC1:RAC1 > > 10.0.0.11=DC1:RAC1 > > 10.0.0.12=DC1:RAC2 > > > 10.20.114.10=DC2:RAC1 > > 10.20.114.11=DC2:RAC1 > > > 10.21.119.13=DC3:RAC1 > > 10.21.119.10=DC3:RAC1 > > > 10.0.0.13=DC1:RAC2 > > 10.21.119.14=DC3:RAC2 > > 10.20.114.15=DC2:RAC2 > > > # default for unknown nodes > > default=DC1:r1 > > > # Native IPv6 is supported, however you must escape the colon in the IPv6 > Address > > # Also be sure to comment out JVM_OPTS="$JVM_OPTS > -Djava.net.preferIPv4Stack= true" > > # in cassandra-env.sh > > fe80\:0\:0\:0\:202\:b3ff\: fe1e\:8329=DC1:RAC3 > > > > > On Tuesday, June 19, 2018, 12:51:34 PM EDT, Durity, Sean R < > sean_r_dur...@homedepot.com> wrote: > > > You are correct that the cluster decides where data goes (based on the > hash of the partition key). However, if you choose a “bad” partition key, > you may not get good distribution of the data, because the hash is > deterministic (it always goes to the same nodes/replicas). For example, if > you have a partition key of a datetime, it is possible that there is more > data written for a certain time period – thus a larger partition and an > imbalance across the cluster. Choosing a “good” partition key is one of the > most important decisions for a Cassandra table. > > > > Also, I have seen the use of racks in the topology cause an imbalance in > the “first” node of the rack. > > > > To help you more, we would need the create table statement(s) for your > keyspace and the topology of the cluster (like with nodetool status). > > > > > > Sean Durity > > *From:* learner dba <cassandra...@yahoo.com. INVALID> > *Sent:* Tuesday, June 19, 2018 9:50 AM > *To:* user@cassandra.apache.org > *Subject:* Re: RE: [EXTERNAL] Cluster is unbalanced > > > > We do not chose the node where partition will go. I thought it is snitch's > role to chose replica nodes. Even the partition size does not vary on our > largest column family: > > Percentile SSTables Write Latency Read Latency Partition Size > Cell Count > > (micros) (micros) (bytes) > > > 50% 0.00 17.08 61.21 3311 > 1 > > 75% 0.00 20.50 88.15 3973 > 1 > > 95% 0.00 35.43 105.78 3973 > 1 > > 98% 0.00 42.51 126.93 3973 > 1 > > 99% 0.00 51.01 126.93 3973 > 1 > > Min 0.00 3.97 17.09 61 > > > Max 0.00 73.46 126.93 11864 > 1 > > > > We are kinda stuck here to identify, what could be causing this un-balance. > > > > On Tuesday, June 19, 2018, 7:15:28 AM EDT, Joshua Galbraith < > jgalbra...@newrelic.com. INVALID> wrote: > > > > > > >If it was partition key issue, we would see similar number of partition > keys across nodes. If we look closely number of keys across nodes vary a > lot. > > I'm not sure about that, is it possible you're writing more new partitions > to some nodes even though each node owns the same number of tokens? > > [image: Image removed by sender.] > > > > On Mon, Jun 18, 2018 at 6:07 PM, learner dba <cassandra...@yahoo.com. > invalid <cassandra...@yahoo.com.invalid>> wrote: > > Hi Sean, > > > > Are you using any rack aware topology? --> we are using gossip file > > Are you using any rack aware topology? --> we are using gossip file > > What are your partition keys? --> Partition key is uniq > > Is it possible that your partition keys do not divide up as cleanly as you > would like across the cluster because the data is not evenly distributed > (by partition key)? --> No, we verified it. > > > > If it was partition key issue, we would see similar number of partition > keys across nodes. If we look closely number of keys across nodes vary a > lot. > > > > > > Number of partitions (estimate): 3142552 > > Number of partitions (estimate): 15625442 > > Number of partitions (estimate): 15244021 > > Number of partitions (estimate): 9592992 > > Number of partitions (estimate): 15839280 > > > > > > > > > > > > On Monday, June 18, 2018, 5:39:08 PM EDT, Durity, Sean R < > sean_r_dur...@homedepot.com> wrote: > > > > > > Are you using any rack aware topology? What are your partition keys? Is it > possible that your partition keys do not divide up as cleanly as you would > like across the cluster because the data is not evenly distributed (by > partition key)? > > > > > > Sean Durity > > lord of the (C*) rings (Staff Systems Engineer – Cassandra) > > MTC 2250 > > #cassandra - for the latest news and updates > > > > *From:* learner dba <cassandra...@yahoo.com. INVALID> > *Sent:* Monday, June 18, 2018 2:06 PM > *To:* User cassandra.apache.org > <https://urldefense.proofpoint.com/v2/url?u=http-3A__cassandra.apache.org&d=DwMFaQ&c=MtgQEAMQGqekjTjiAhkudQ&r=aC_gxC6z_4f9GLlbWiKzHm1vucZTtVYWDDvyLkh8IaQ&m=8q4p6nWedWQJ9gpXCnoa6KR4HRmSf3B1whdYKNFub6M&s=TmzIaVextVyZy81p9JuU7R6PFv84RfhgtEezCe063V0&e=> > <user@cassandra.apache.org> > *Subject:* [EXTERNAL] Cluster is unbalanced > > > > Hi, > > > > Data volume varies a lot in our two DC cluster: > > Load Tokens Owns > > 20.01 GiB 256 ? > > 65.32 GiB 256 ? > > 60.09 GiB 256 ? > > 46.95 GiB 256 ? > > 50.73 GiB 256 ? > > kaiprodv2 > > ========= > > /Leaving/Joining/Moving > > Load Tokens Owns > > 25.19 GiB 256 ? > > 30.26 GiB 256 ? > > 9.82 GiB 256 ? > > 20.54 GiB 256 ? > > 9.7 GiB 256 ? > > > > I ran clearsnapshot, garbagecollect and cleanup, but it increased the size > on heavier nodes instead of decreasing. Based on nodetool cfstats, I can > see partition keys on each node varies a lot: > > > > Number of partitions (estimate): 3142552 > > Number of partitions (estimate): 15625442 > > Number of partitions (estimate): 15244021 > > Number of partitions (estimate): 9592992 > > Number of partitions (estimate): 15839280 > > > > How can I diagnose this imbalance further? > > > > > > > > -- > > *Joshua Galbraith *| Senior Software Engineer | New Relic > C: 907-209-1208 | jgalbraith@ newrelic.com <jgalbra...@newrelic.com> > > > > > -- > *Joshua Galbraith *| Senior Software Engineer | New Relic > > > > > -- > *Joshua Galbraith *| Senior Software Engineer | New Relic > -- *Joshua Galbraith *| Senior Software Engineer | New Relic
