Why can’t the haproxy-replicas Service be used for write requests?

MySQL & MariaDB Percona Operator for MySQL
1

In the documentation from Custom Resource options - Percona Operator for MySQL based on Percona XtraDB Cluster

You state that the haproxy-replicas should not be used for write requests.

Where does that come from? Doesn’t the XtraDB cluster use a multi-master Galera cluster which enables writing to all nodes?

If for some reason it’s not recommended, is it enforceable? Because once you offer the additional service to developers, you can’t just count on people to respect that restriction.

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@gmautner As you know XtraDB cluster uses a multi-master Galera cluster which enables writing to all nodes and you can use haproxy-replicas for writes. We did not add any limitations to it. But as a result, the performance of your cluster will be not good. This service was created to have the possibility to read from all available PXC pods. Using cluster_name-haproxy service you can’t get this functionality.