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Ensure cpp-rust-driver handles zero-token nodes properly #203

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dkropachev opened this issue Aug 4, 2024 · 2 comments
Open

Ensure cpp-rust-driver handles zero-token nodes properly #203

dkropachev opened this issue Aug 4, 2024 · 2 comments
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enhancement New feature or request rust-driver-missing Functionality that Rust driver needs to implement first

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@dkropachev
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dkropachev commented Aug 4, 2024

PR#19684 brings possibility of having nodes coordinator-only nodes (or zero-token nodes).
These types of nodes are going to be supported only in RAFT.

Such nodes, despite being registered in the cluster, do not handle any queries and should be excluded from query routing.
This feature is already present in cassandra, but not merged into scylla yet, so we might want to start testing it on our drivers with cassandra first.

Difference between cassandra and scylla implementation

Major difference is that these nodes are absent from system.peers and system.peers_v2 in cassandra, while in scylla implementation these nodes are going to be present there.

Due to this fact we will need to test Apache and datastax drivers against scylla as well.

Approx. Testing plan

Regular cluster

  1. Spin up a cluster with 3 nodes
  2. Join one additional node in zero-token mode, by setting join_ring to false in it's configuration, or adding -Dcassandra.join_ring=false to cli (cassandra only).
  3. Make sure that drivers works as expected and do not throw any errors while reading schema with this node being in the cluster
  4. Make sure that drivers works as expected and do not throw any errors while processing topology events (if these events issues) when such node joins/leaves cluster.
  5. Make sure that zero-token node does not participate in the routing
  6. Test if driver works properly if only connection point provided is zero-token node
  7. Ensure that at no point driver throw error or warning caused by zero-token node presence.

Cluster that starts with zero-token node (DROPPED)

  1. Start single node cluster with join_ring=false
  2. Connect to it, to make sure that driver session is created and every query end up in no host available error.
  3. Populate cluster with 3 more nodes
  4. Make sure that driver can execute queries
  5. Ensure that at no point driver throw error or warning.

Zero-token Datacenter

Repeat this scenario for following policies:

  1. DCAwareRoundRobinPolicy
  2. TokenAwareHostPolicy(DCAwareRoundRobinPolicy())
  3. TokenAwareHostPolicy(RoundRobinHostPolicy())

For DCAwareRoundRobinPolicy use three variants:

  1. Target first DC with real nodes
  2. Target second DC with zero token nodes
  3. (For drivers that supports it, gocql does not) Do not target any DC, make sure that policy won't pick datacenter with no real nodes.

Steps:
3. Start cluster of 2 nodes with 1 DC
4. Provision 2 more nodes into 2nd DC in join_ring=false mode
5. Connect to the cluster, using policy to make sure that driver session is created and every query is being scheduled to regular nodes and executed successfully. In cases when zero-token DC is targeted queries suppose to fail with no host available error

Links

Original umbrella issue in scylladb/scylladb repo: scylladb/scylladb#19693
Core issue to bring join_ring option into scylla: scylladb/scylladb#6527
PR that brings this feature in scylladb/scylladb#19684

@Lorak-mmk
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We probably won't be implementing it here, but in rust-driver (and thus in cpp-rust-driver). Do we need this issuse?

@mykaul mykaul closed this as not planned Won't fix, can't repro, duplicate, stale Aug 8, 2024
@roydahan roydahan transferred this issue from scylladb/cpp-driver Nov 18, 2024
@roydahan
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Moved to cpp-rust-driver and reopening to make sure we have it there after rust-driver implementation.

@roydahan roydahan reopened this Nov 18, 2024
@roydahan roydahan added rust-driver-missing Functionality that Rust driver needs to implement first enhancement New feature or request labels Nov 18, 2024
@roydahan roydahan changed the title Ensure cpp-driver handles zero-token nodes properly Ensure cpp-rust-driver handles zero-token nodes properly Nov 18, 2024
@dkropachev dkropachev assigned dkropachev and muzarski and unassigned muzarski and dkropachev Nov 18, 2024
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