Description:
Take a look at https://dev.mysql.com/doc/internals/en/com-sleep.html. This page is useless, it does not explain when server uses this command.
In reality it is used in different places:
openxs@ao756:~/git/mysql-server$ grep -rn COM_SLEEP *
include/mysql/plugin_audit.h.pp:130: COM_SLEEP,
include/mysql.h.pp:35: COM_SLEEP,
include/my_command.h:30: COM_SLEEP,
libmysqld/lib_sql.cc:752: thd->set_command(COM_SLEEP);
sql/sql_connect.cc:825: thd->set_command(COM_SLEEP);
sql/protocol_classic.cc:1391: /* Initialize with COM_SLEEP packet */
sql/protocol_classic.cc:1392: raw_packet[0]= (uchar) COM_SLEEP;
sql/sql_show.cc:2085: else if (tmp->get_command() == COM_SLEEP)
sql/sql_parse.cc:261: server_command_flags[COM_SLEEP]= CF_ALLOW_PROTOCOL_PLUGIN;
sql/sql_parse.cc:1857: case COM_SLEEP:
sql/sql_parse.cc:1900: thd->set_command(COM_SLEEP);
sql/sql_audit.cc:746: command == COM_SLEEP || /* Deprecated commands from here. */
sql/srv_session.cc:920: thd.set_command(COM_SLEEP);
openxs@ao756:~/git/mysql-server$
(this is from current 8.0 code)
It would be nice to explain when exactly it is used and why one may find entries like these:
SET timestamp=1473712798;
# administrator command: Sleep;
# Time: 160912 20:39:59
# User@Host: user[host] @ [192.168.1.51]
# Thread_id: 36310042 Schema: somedb QC_hit: No
# Query_time: 17.201526 Lock_time: 0.000000 Rows_sent: 0 Rows_examined: 0
in the slow log.
How to repeat:
Try to explain what does this entry mean in the slow query log:
SET timestamp=1473712798;
# administrator command: Sleep;
# Time: 160912 20:39:59
# User@Host: user[host] @ [192.168.1.51]
# Thread_id: 36310042 Schema: somedb QC_hit: No
# Query_time: 17.201526 Lock_time: 0.000000 Rows_sent: 0 Rows_examined: 0
Why Sleep took time, was it a problem, why this was logged as slow query etc
Suggested fix:
Document all cases of COM-SLEEP use in the server code in internal manual.
Explain in the manual for slow query log what entries like this:
SET timestamp=1473712798;
# administrator command: Sleep;
# Time: 160912 20:39:59
# User@Host: user[host] @ [192.168.1.51]
# Thread_id: 36310042 Schema: somedb QC_hit: No
# Query_time: 17.201526 Lock_time: 0.000000 Rows_sent: 0 Rows_examined: 0
mean.
