Add metrics from information_schema.innodb_metrics

[SuperQ]

Add metrics from information_schema.innodb_metrics.

• Ignore status_counter metrics duplicatd by SHOW GLOBAL STATUS
• Only show enabled metrics.

[SuperQ]

Example output:

# HELP mysql_info_schema_innodb_metrics_dml Innodb metrics subsystem dml
# TYPE mysql_info_schema_innodb_metrics_dml gauge
mysql_info_schema_innodb_metrics_dml{comment="Number of rows deleted",name="dml_deletes",type="status_counter"} 6.2238132e+07
mysql_info_schema_innodb_metrics_dml{comment="Number of rows inserted",name="dml_inserts",type="status_counter"} 1.83984556e+08
mysql_info_schema_innodb_metrics_dml{comment="Number of rows read",name="dml_reads",type="status_counter"} 1.16084019171e+11
mysql_info_schema_innodb_metrics_dml{comment="Number of rows updated",name="dml_updates",type="status_counter"} 1.72289574e+08

[matthiasr]

How about using the type to make it a counter where appropriate?

[SuperQ]

I tried that and had issues with conflicting types. Maybe it was a bug in my implementation. Will poke around a bit.

[beorn7]

I like @brian-brazil 's suggestion:

• innodb metric types value and status_counter would map into gauges, counter to counter
• innodb names look good to me as Prometheus names. Counters should get a _total appended, though.
• comment is about perfect as help text.

[SuperQ]

status_counter is apparently counters that are duplicated in SHOW GLOBAL STATUS. I think it would be reasonable to simply exclude them.

[SuperQ]

Ok, I've updated the metrics. Example output now looks like:

# HELP mysql_info_schema_innodb_metrics_file_system_file_num_open_files Number of files currently open (innodb_num_open_files)
# TYPE mysql_info_schema_innodb_metrics_file_system_file_num_open_files gauge
mysql_info_schema_innodb_metrics_file_system_file_num_open_files 118
# HELP mysql_info_schema_innodb_metrics_lock_lock_deadlocks_total Number of deadlocks
# TYPE mysql_info_schema_innodb_metrics_lock_lock_deadlocks_total counter
mysql_info_schema_innodb_metrics_lock_lock_deadlocks_total 0

[beorn7]

👍