updating a unique key can cause parallel applying to hang
|MySQL patches by Codership||Status tracked in 5.6|
|Percona XtraDB Cluster||Status tracked in 5.6|
updating a unique key value can cause server hang if slave node has enabled parallel slaves.
This seems to to be because such updates will require extra reads (with S locks) to make sure that there will be no duplicate keys with he new key value. These S locks were not taken in account when forming the write set, and we have a "asymmetric lock granularity" issue here.
To make this issue to surface, you will need high conflict rate updates on unique keys.
|Changed in codership-mysql:|
|status:||New → In Progress|
|importance:||Undecided → High|
|assignee:||nobody → Seppo Jaakola (seppo-jaakola)|
|milestone:||none → 5.1.63-23.5|