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gotchas.md

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Gotchas

  • By default, orchestrator only polls a server once a minute (configurable via InstancePollSeconds). This means that any status you see is essentially an estimation. Different instances get polled at different times. The status you see on the cluster page, for example, does not necessarily reflect a given point in time, but rather a combination of different points in time in the last minute (or whatever poll interval you use).

The problems drop down to the right is also executed asynchonously. You may therefore see the same instance in two places (once in the cluster page, once in the problems drop down) in two different states.

If you want to get the most up to date instance status, use the "Refresh" button on the instance's settings dialog.

  • Similarly, on Long Queries page the queries presented are true to a point in time in the last minute (or otherwise the InstancePollSeconds settgins). Thus, it is possible that by the time you look at this page, the queries listed will have been completed. If you choose to click the Kill query button, please be advised that you might actually be killing a different query, executing on same connection following up on the by-now-completed listed long running query.

  • It make take a couple minutes for orchestrator to full detect a cluster's topology. The time depends on the depth of the topology (if you have replicas-of-replicas the time increases). This is due to the fact orchestrator polls the instances independently, and and insight on the topology must propagate from master to replica on the next polling occasion.

  • Specifically, if you fail over to a new master, you may find that for a couple minutes the topologies seem empty. This may happen because instances used to identify themselves as belonging to a certain topology that is now being destroyed. This is self-healing. Refresh and look at the Clusters menu to review the newly created cluster (names after the new master) over time.

  • Don't restart orchestrator while you're running a seed (only applies to working with orchestrator-agent)

Otherwise orchestrator is non-intrusive and self-healing. You can restart it whenever you like.