From abe6eb10a65d5c28c221d756357b4e7f392ad13d Mon Sep 17 00:00:00 2001 From: Sujatha Date: Fri, 30 Apr 2021 18:12:43 +0530 Subject: MDEV-16146: MariaDB slave stops with following errors. Problem: ======== 180511 11:07:58 [ERROR] Slave I/O: Unexpected master's heartbeat data: heartbeat is not compatible with local info;the event's data: log_file_name mysql-bin.000009 log_pos 1054262041, Error_code: 1623 Analysis: ========= In replication setup when master server doesn't have any events to send to slave server it sends an 'Heartbeat_log_event'. This event carries the current binary log filename and offset details. The offset values is stored within 4 bytes of event header. When the size of binary log is higher than UINT32_MAX the log_pos values will not fit in 4 bytes memory. It overflows and hence slave stops with an error. Fix: === Since we cannot extend the common_header of Log_event class, a greater than 4GB value of Log_event::log_pos is made to be transported with a HeartBeat event's sub-header. Log_event::log_pos in such case is set to zero to indicate that the 8 byte sub-header is allocated in the event. In case of cross version replication following behaviour is expected OLD - Server without fix NEW - Server with fix OLD<->NEW : works bidirectionally as long as the binlog offset is (normally) within 4GB. When log_pos > UINT32_MAX OLD->NEW : The 'log_pos' is bound to overflow and NEW slave may report an invalid event/incompatible heart beat event error. NEW->OLD : Since patched server sets log_pos=0 on overflow, OLD slave will report invalid event error. --- sql/log_event.h | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) (limited to 'sql/log_event.h') diff --git a/sql/log_event.h b/sql/log_event.h index 3fc44a9669f..bd40795a7fb 100644 --- a/sql/log_event.h +++ b/sql/log_event.h @@ -570,6 +570,14 @@ class String; #define MARIA_SLAVE_CAPABILITY_MINE MARIA_SLAVE_CAPABILITY_GTID +/* + When the size of 'log_pos' within Heartbeat_log_event exceeds UINT32_MAX it + cannot be accommodated in common_header, as 'log_pos' is of 4 bytes size. In + such cases, sub_header, of size 8 bytes will hold larger 'log_pos' value. +*/ +#define HB_SUB_HEADER_LEN 8 + + /** @enum Log_event_type @@ -5160,12 +5168,13 @@ static inline bool copy_event_cache_to_file_and_reinit(IO_CACHE *cache, class Heartbeat_log_event: public Log_event { public: - Heartbeat_log_event(const char* buf, uint event_len, + uint8 hb_flags; + Heartbeat_log_event(const char* buf, ulong event_len, const Format_description_log_event* description_event); Log_event_type get_type_code() { return HEARTBEAT_LOG_EVENT; } bool is_valid() const { - return (log_ident != NULL && + return (log_ident != NULL && ident_len <= FN_REFLEN-1 && log_pos >= BIN_LOG_HEADER_SIZE); } const char * get_log_ident() { return log_ident; } -- cgit v1.2.1