Wrong type for MySQL enum variables with OFF value

[fxedel]

Relevant telegraf.conf:

[[inputs.mysql]]
  servers = ["..."]
  metric_version = 2
  interval_slow = "0s"
  # ...

System info:

Telegraf 1.14.0 (git: HEAD fefd7ff)
Debian GNU/Linux 9 (stretch)

Description

Some MySQL variables, like transaction_write_set_extraction, allow for multiple string values including OFF, e.g.: OFF, MURMUR32 or XXHASH64.

I expected these variables to be gathered as string, however, the Off value is converted to the integer 0 in ParseValue. This conversion is good for simple On/Off variables, but doesn't fit for enumerations like transaction_write_set_extraction as it produces errors like these:

2020-04-28T08:35:30Z E! [outputs.influxdb] When writing to [https://...:8086]: received error partial write: field type conflict: input field "transaction_write_set_extraction" on measurement "mysql_variables" is type string, already exists as type integer dropped=3; discarding points

Proposed fix

I don't know what the best solution would be; maybe a hardcoded list of variables that should parse On/Off as string?

[telegraf-tiger]

Hello! I am closing this issue due to inactivity. I hope you were able to resolve your problem, if not please try posting this question in our Community Slack or Community Page. Thank you!

[fxedel]

Fixed with #9403