Hi, After upgrading from TokuDB Enterprise with MariaDB 5.5 to MariaDB 10.1.14, I tried to enable the parallel replication (parallel_mode=optimistic, slave_parallel_threads=4) on a GTID enabled RFR slave, but it leads to random failures. (both master & slave are running 10.1.14) E.g : Could not execute Update_rows_v1 event on table sc_2.sc_param_index; Can't find record in 'sc_param_index', Error_code: 1032; handler error HA_ERR_KEY_NOT_FOUND; the event's master log mysql-bin.008418, end_log_pos 217608066 If I issue a start slave (with sql_slave_skip_counter=0) : Could not execute Update_rows_v1 event on table sc_2.sc_log_cron; Can't find record in 'sc_log_cron', Error_code: 1032; handler error HA_ERR_KEY_NOT_FOUND; the event's master log mysql-bin.008418, end_log_pos 218275984 If I put back slave_parallel_threads to 0, the slave keeps replicating happily without any issue. Is this a known limitation with TokuDB ? Tokudb configuration : tokudb_rpl_lookup_rows=0 tokudb_rpl_unique_checks=0 tokudb_pk_insert_mode=2 tokudb_directio = 1 Thanks and regards, Jocelyn Fournier