Cassandra Check Schema Agreement

Users who want to be informed of schematic changes can implement the SchemaChangeListener interface. If it didn`t work, it means that the other scheme is the one that decided is the authority, so repeat those steps for the node list in the first list of diagrams. If there are more nodes in one pattern than in the other, you can first try to restart a Cassandra node in the smaller list and see if it adheres to the other list. If all went well, you should see that the node “” has been moved to the other schematic list (Note: The node list is not sorted by IP): now check the status to see if the expiration process is complete. Similarly, here is the layout of the reservation key area: we found a contribution from StackOverlow that suggests that a solution to the problem of inconsistency of the scheme was to go through the nodes one after the other. We tried, and it worked. Here are the steps that worked for us. The test is implemented by repeatedly querying the system tables for the schematic version reported by each node until they all converge towards the same value. If this is not the case within a specific time frame, the driver abandons the wait. The default time is 10 seconds, it can be customized when creating Du Cluster: Note that it`s best to save a lister only after the full initialization of the cluster, otherwise the lister could be notified of a large number of “added” events because the driver is reinventing the metadata for the first time. The schematic changes must be transmitted to all nodes in the cluster. Once they have agreed on a common version, we say they agree.

To study the inconsistencies of the scheme, try nodetool describecluster: You can also perform an on-demand review at any time: there was our problem! We had a schematic disagreement! Three knots in our six-knot cluster were on a different pattern: once you completed the above steps on each node, all the nodes should now be on a single pattern: in our case, we had exactly three knots on each diagram. In this case, it is more likely that the nodes in the first diagram are the nodes that Cassandra will select during a schematic negotiation, so try the following instructions on one of the nodes in the second list of diagrams. During schematic migration, it is necessary to wait for the cluster to transmit the diagram to all nodes. The scheme agreement is implemented on the basis of this update and made available by the abstract migration class. To execute an instruction with a schematic contract, you can use the executeWithSchemaGreement method. We looked at DataStax, which had the article on inconsistencies with the scheme. However, their official documentation was poorly documented and assumed that a node was not accessible. Once you have completed the evaluation and refinement of the physical model, you can implement the CQL scheme. Here is the diagram of the key space of the hotel, with the comment function CQL, which documents the query model supported by each table: After the registration, the lister is informed of all the schematic changes detected by the driver, regardless of the origin. Wait five minutes and run nodetool describecluster to check that the diagram is synchronized. The waiting file for the configuration agreement is run synchronously, so that the execution call – or the conclusion of ResultSetFuture if you use the asynchronous API – will not be returned until after the conclusion.

Although it is possible to increase “migration_task_wait_in_seconds” to force the node to wait longer on each lock, there are cases where this doesn`t help, as recalls for the pull-pull schema have gone from the mail service recall assignment (` after request_timeout_in_ms (standard 10 seconds) before the other nodes could respond to the new node.