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MXS-3158 Preserve character set and collation when altering events

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During switchover/failover, server events are altered. The ALTER
EVENT command automatically modifies the event charset and collation
to the values of the connetion running the query. This may cause
the event to become invalid.

Fixed this by changing connection charset and collation to the ones
in the event description just before altering it.
This commit is contained in:
Esa Korhonen 2020-12-09 17:43:50 +02:00
parent ce85a7292f
commit 0c904eae5e
3 changed files with 43 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
server/core/monitor.cc
View File

@ -1162,6 +1162,7 @@ Monitor::ping_or_connect_to_db(const MonitorServer::ConnectionSettings& sett, SE
mysql_optionsv(pConn, MYSQL_OPT_READ_TIMEOUT, &sett.read_timeout);
mysql_optionsv(pConn, MYSQL_OPT_WRITE_TIMEOUT, &sett.write_timeout);
mysql_optionsv(pConn, MYSQL_PLUGIN_DIR, get_connector_plugindir());
mysql_optionsv(pConn, MARIADB_OPT_MULTI_STATEMENTS, nullptr);
time_t start = time(NULL);
if (mxs_mysql_real_connect(pConn, &server, uname.c_str(), dpwd))

54
server/modules/monitor/mariadbmon/mariadbserver.cc
View File

@ -104,18 +104,30 @@ bool MariaDBServer::execute_cmd_ex(const string& cmd, QueryRetryMode mode,
bool rval = false;
if (query_success)
{
MYSQL_RES* result = mysql_store_result(conn);
if (result == NULL)
// In case query was a multiquery, loop for more resultsets. Error message is produced from first
// non-empty resultset and does not specify the subquery.
string results_errmsg;
do
{
MYSQL_RES* result = mysql_store_result(conn);
if (result)
{
int cols = mysql_num_fields(result);
int rows = mysql_num_rows(result);
if (results_errmsg.empty())
{
results_errmsg = string_printf("Query '%s' on '%s' returned %d columns and %d rows "
"of data when none was expected.",
cmd.c_str(), name(), cols, rows);
}
}
}
while (mysql_next_result(conn) == 0);
if (results_errmsg.empty())
{
rval = true;
}
else if (errmsg_out)
{
int cols = mysql_num_fields(result);
int rows = mysql_num_rows(result);
*errmsg_out = string_printf("Query '%s' on '%s' returned %d columns and %d rows of data when "
"none was expected.", cmd.c_str(), name(), cols, rows);
}
}
else
{
@ -1285,6 +1297,12 @@ MariaDBServer::alter_events(BinlogMode binlog_mode, const EventStatusMapper& map
{
if (target_events > 0)
{
// Reset character set and collation.
string charset_errmsg;
if (!execute_cmd("SET NAMES latin1 COLLATE latin1_swedish_ci;", &charset_errmsg))
{
MXS_ERROR("Could not reset character set: %s", charset_errmsg.c_str());
}
warn_event_scheduler();
}
if (target_events == events_altered)
@ -1350,7 +1368,10 @@ bool MariaDBServer::events_foreach(EventManipulator& func, json_t** error_out)
auto event_name_ind = event_info->get_col_index("EVENT_NAME");
auto event_definer_ind = event_info->get_col_index("DEFINER");
auto event_status_ind = event_info->get_col_index("STATUS");
mxb_assert(db_name_ind > 0 && event_name_ind > 0 && event_definer_ind > 0 && event_status_ind > 0);
auto charset_ind = event_info->get_col_index("CHARACTER_SET_CLIENT");
auto collation_ind = event_info->get_col_index("COLLATION_CONNECTION");
mxb_assert(db_name_ind > 0 && event_name_ind > 0 && event_definer_ind > 0 && event_status_ind > 0
&& charset_ind > 0 && collation_ind > 0);
while (event_info->next_row())
{
@ -1358,6 +1379,8 @@ bool MariaDBServer::events_foreach(EventManipulator& func, json_t** error_out)
event.name = event_info->get_string(db_name_ind) + "." + event_info->get_string(event_name_ind);
event.definer = event_info->get_string(event_definer_ind);
event.status = event_info->get_string(event_status_ind);
event.charset = event_info->get_string(charset_ind);
event.collation = event_info->get_string(collation_ind);
func(event, error_out);
}
return true;
@ -1395,10 +1418,13 @@ bool MariaDBServer::alter_event(const EventInfo& event, const string& target_sta
quoted_definer = event.definer;
}
string alter_event_query = string_printf("ALTER DEFINER = %s EVENT %s %s;",
quoted_definer.c_str(),
event.name.c_str(),
target_status.c_str());
// Change character set and collation to the values in the event description. Otherwise, the event
// values could be changed to whatever the monitor connection happens to be using.
string alter_event_query = string_printf(
"SET NAMES %s COLLATE %s; ALTER DEFINER = %s EVENT %s %s;",
event.charset.c_str(), event.collation.c_str(), quoted_definer.c_str(), event.name.c_str(),
target_status.c_str());
if (execute_cmd(alter_event_query, &error_msg))
{
rval = true;

2
server/modules/monitor/mariadbmon/mariadbserver.hh
View File

@ -82,6 +82,8 @@ public:
std::string name; /**< Event name in <database.name> form */
std::string definer; /**< Definer of the event */
std::string status; /**< Status of the event */
std::string charset; /**< character_set_client-field */
std::string collation; /**< collation_connection-field */
};
enum class server_type