Knowledge Base

Articles tagged as cluster

Comparing HA and Causal Clusters

The legacy HA cluster mode has been deprecated as of Neo4j version 3.5, and will be totally removed from the product in version 4.0, with 4.0 expected to be released…

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Configure HAProxy to Send Write Requests to Leader Node Only

There are a few options regarding implementation of a proxy server to direct writes to a Master node and reads to the Slave nodes in a Neo4j cluster. Commonly, it…

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How do I resolve inconsistency problems on an instance of a cluster

(if using version >= 3.1, please read Leader and Follower instead of Master and Slave respectively) Sometimes, when running a clustered Neo4j environment, a slave’s store may become inconsistent. On…

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Creating and working with linked lists in Cypher

At some point when working with a graph, you may want to create a linked list out of some nodes. If each of the nodes to be linked has its…

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Diagnosing network latency in a Causal Cluster using MTR

MTR is a simple ICMP based test combining ping and traceroute. The following demonstrates usage of the MTR trace tool to diagnose network latency and packet loss in a Causal…

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Explanation of "Failed to update routing table with server" error

If you encounter a Failed to update routing table with server error in their $NEO4J_HOME/logs/debug.log similar to: This can be addressed by checking your DNS entries. A routing driver is…

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HA Proxy Configuration for Online Backup

What are we trying to achieve? Online backup should be scheduled to run periodically on a production cluster. You only need to run it on one instance, since each has…

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How to monitor if a follower is in sync with Leader (Causal Cluster)

To monitor if a Follower is in sync with its Leader, or know how much it is lagging behind, it is possible to check the Last Commited Transaction Id from…

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Solving the "Store copy failed due to store ID mismatch" error

It is possible that after seeding a cluster or restoring from a backup, you may encounter the following error while starting your cluster: In most of the cases, this issue…

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Mitigating Causal Cluster re-elections caused by high GCs

This article describes the effects of JVM stop-the-world GC pauses, on a causal cluster. A brief introduction to garbage collection, heap sizing and memory leak troubleshooting, is followed by a…

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Neo4j’s commit process explained

This article will try to guide you through Neo4j’s commit and replication processes both for single instances and causal clusters. Single Instance When you call tx.commit(), the transaction will go…

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Planning Data Center Migration

The following KB describes the process that you can use utilizing backup (or Read-Replicas) in order to migrate (and/or upgrade) from one datacenter(DC1) to another(DC2) in a rolling fashion with…

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Understanding causal cluster quorum and cluster recovery

Several major causal cluster operations require a majority of cluster members to be online, a majority quorum. When a causal cluster loses majority quorum, it loses write capability as well…

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Understanding causal cluster size scaling

The ability to safely scale down the size of a causal cluster affords us more robustness for instance failures, provided we maintain quorum as the failures take place. Prior to…

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When to use bookmarks

Bookmarks are part of a broader topic: Causal consistency. We recommend reading the introduction to Neo4j Causal Clustering and the lifecycle of a Neo4j Causal Cluster before reading further. Pay…

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