Hello, we are using Percona Cluster (5.6.32-78.1-56-log). 3 nodes cluster (2 nodes and 1 arbiter). yesterday during schema migration using pt-osc we got cluster stuck. There was CREATE TRIGGER pt_osc_x_del statement in “Waiting for table metadata lock” state which blocked the whole cluster. Killing all of queries (including sleep queries) on both nodes didn’t help and we only able to get cluster working after shut down one of the nodes. Trying to investigate the reason I found in Galera documentation that with TOI enabled DDL should not be locked with metadata lock at all:
Is there still any way to get MDL? I believe this may help me to reproduce the problem.