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Cassandra [5e6d1746]

Tags: Databases, distributed systems

1. Internals

  • Seed nodes:

    • No purpose other than bootstrapping the gossip process
    • DO NOT MAKE ALL NODES SEED NODES

2. concurrent_compactors

  • Sets the number of IO threads dedicated to compaction

  • If too high, can cause IO starvation and not servicing requests

    • Depends on NVME drives

  • set by the concurrenct_compactors string in yaml

    • can also use nodetool setconcurrent_compactors in C* > 3

3. Counter Table TTL's

4. Jolokia Agent

5. CQLSH

  • cqlsh specifically checks for python2.7, which may need to be aliased somewhere

6. Scylla

6.1. Tracing

7. Cassandra Gossiper Protocol

  • Gossiper chooses a random node in the cluster and initializes a session with it

    • each gossip require 3 messages
  • Sends its friend a Gossip Disget Syn Message
  • Followed by a GossipDigestAck message
  • Th eoriginal ack is returned with a gossip digestack2 message

8. Talks