Modified required grants in README.md

[guidoiaquinti]

After reviewing the collectors code I think we can reduce the scope of the MySQL grants to strictly mentions what it needs to run.

I'm not sure we really need

GRANT SELECT ON `information_schema`.* TO 'exporter'@'localhost';

as for InnoDB tables it should be indirectly granted by the PROCESS privilege (at least on MySQL 5.7+).

[SuperQ]

How about: "You will need to grant the exporter access to the heartbeat table:"

[brian-brazil]

I have a vague recollection that SELECT was required on *.* for some of the performance schema to work. Is that no longer the case?

[guidoiaquinti]

I might be missing something but I don't think that's the case:

• perf_schema_events_statements.go
• perf_schema_events_waits.go
• perf_schema_file_events.go
• perf_schema_file_instances.go
• perf_schema_index_io_waits.go
• perf_schema_table_io_waits.go
• perf_schema_table_lock_waits.go

[brian-brazil]

I don't mean that the query reference it directly, I meant that there was additional access control under the covers in MySQLd that required a broad SELECT.

[guidoiaquinti]

👍 got it. Unfortunately without integration tests running for all the supported MySQL versions I'm not sure how we can verify it.

[brian-brazil]

Ah, #153

[SuperQ]

@brian-brazil Yea, that's the one. We still support MySQL 5.1, and *.* is required for those versions.

[SuperQ]

Since this won't work on older versions, I think we have to close this for now.