Hi Lars, Thanks for your reply. Please note that we experienced a crash again this morning, while all optimise queries were removed from our batches ... so I fear it might be misleading. I will try to reproduce the crash in a VM. In the meantime, please find our mysqld configuration file below: ================================================================== Master configuration ================================================================== # MySQL 5.7 configuration (2016.07.13 - made by efj) # For explanations see http://dev.mysql.com/doc/mysql/en/server-system-variables.html # Remember to edit /etc/mysql/debian.cnf when changing the socket location. [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] # Basic Settings - do not touch user = mysql pid-file = /var/run/mysqld/mysqld.pid socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp lc-messages-dir = /usr/share/mysql skip-external-locking skip-name-resolve # Limiting maximum amount of connexions max_connections = 250 max_user_connections = 50 # Security sql_mode = '' # Default options for new db/tables default-storage-engine=InnoDB character-set-server=utf8 collation-server=utf8_general_ci # Fine tuning for full text searches - At least 3 characters ft_min_word_len=2 # Accept incoming connections from all clients bind-address = 0.0.0.0 # Fine Tuning key_buffer_size = 16M max_allowed_packet = 48M thread_stack = 192K thread_cache_size = 8 # This replaces the startup script and checks MyISAM tables if needed, the first time they are touched myisam-recover-options = BACKUP # Query Cache Configuration query_cache_limit = 1M query_cache_size = 128M # Error log - should be very few entries. log_error = /var/log/mysql/error.log # Slow queries slow_query_log = 1 slow_query_log_file = /var/log/mysql/mysql-slow.log # Logging and Replication server-id = 7 log_bin = /var/log/mysql/mysql-bin.log expire_logs_days = 5 max_binlog_size = 100M log-slave-updates master_info_repository=TABLE relay_log_info_repository=TABLE relay_log=relay-bin.log # InnoDB server specific configuration innodb_buffer_pool_size = 150G innodb_log_file_size = 256M innodb_log_buffer_size=4M innodb_flush_log_at_trx_commit = 2 innodb_flush_method = O_DIRECT innodb_thread_concurrency = 8 innodb_file_per_table ================================================================== Slave configuration ================================================================== # MySQL 5.7 configuration (2016.07.13 - made by efj) # For explanations see http://dev.mysql.com/doc/mysql/en/server-system-variables.html # Remember to edit /etc/mysql/debian.cnf when changing the socket location. [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] # Basic Settings - do not touch user = mysql pid-file = /var/run/mysqld/mysqld.pid socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp lc-messages-dir = /usr/share/mysql skip-external-locking skip-name-resolve # Limiting maximum amount of connexions max_connections = 250 max_user_connections = 50 # Default options for new db/tables default-storage-engine=InnoDB character-set-server=utf8 collation-server=utf8_general_ci # Security sql_mode = '' # Fine tuning for full text searches - At least 3 characters ft_min_word_len=2 # Accept incoming connections from all clients bind-address = 0.0.0.0 # Fine Tuning key_buffer_size = 16M max_allowed_packet = 48M thread_stack = 192K thread_cache_size = 8 # This replaces the startup script and checks MyISAM tables if needed, the first time they are touched myisam-recover-options = BACKUP # Query Cache Configuration query_cache_limit = 1M query_cache_size = 128M # Error log - should be very few entries. log_error = /var/log/mysql/error.log # Slow queries slow_query_log = 1 slow_query_log_file = /var/log/mysql/mysql-slow.log # Logging and Replication server-id = 8 log_bin = /var/log/mysql/mysql-bin.log expire_logs_days = 3 max_binlog_size = 100M log-slave-updates master_info_repository=TABLE relay_log_info_repository=TABLE relay_log=relay-bin.log # InnoDB server specific innodb_buffer_pool_size = 150G innodb_log_file_size = 256M innodb_log_buffer_size=4M innodb_flush_log_at_trx_commit = 2 innodb_flush_method = O_DIRECT innodb_thread_concurrency = 8 innodb_file_per_table ================================================================== PhpMyAdmin dump of the *supposed to be* problematic table ================================================================== -- phpMyAdmin SQL Dump -- version 4.7.5 -- https://www.phpmyadmin.net/ -- -- Host: sql-master:3306 -- Generation Time: Dec 08, 2017 at 08:23 AM -- Server version: 5.7.19-0ubuntu0.16.04.1-log -- PHP Version: 7.1.9 SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO"; SET AUTOCOMMIT = 0; START TRANSACTION; SET time_zone = "+00:00"; -- -- Database: `members` -- -- -------------------------------------------------------- -- -- Table structure for table `Members` -- CREATE TABLE `Members` ( `id` varchar(9) NOT NULL, `memberType` enum('TYPE_1','TYPE_2','TYPE_3','TYPE_4','TYPE_5','TYPE_6','TYPE_7') NOT NULL, `name` varchar(30) NOT NULL, `street` varchar(46) NOT NULL, `postalCode` varchar(7) NOT NULL, `location` varchar(25) NOT NULL, `phone` varchar(10) NOT NULL, `fax` varchar(10) NOT NULL, `countryCode` varchar(10) NOT NULL, `language` enum('BEL-fr','BEL-nl') NOT NULL, `enabled` char(1) NOT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8; -- -- Indexes for dumped tables -- -- -- Indexes for table `Members` -- ALTER TABLE `Members` ADD PRIMARY KEY (`id`), ADD UNIQUE KEY `ebis` (`id`,`name`), ADD KEY `memberType` (`memberType`,`postalCode`,`enabled`), ADD KEY `enabled` (`enabled`,`memberType`); ALTER TABLE `Members` ADD FULLTEXT KEY `id` (`id`,`name`,`street`,`postalCode`,`location`); ALTER TABLE `Members` ADD FULLTEXT KEY `id_2` (`id`,`name`); COMMIT; ================================================================== Thanks in advance for your help. Eric