SQL Server Case Sensitive Input plugin issue

[valerian1978]

Bug report

No BufferPoolRate information when running sql server input against a case sensitive instance

System info:

SQL Server Collation: Latin1_General_BIN (Case sensitive)
Telegraf Version: Telegraf v1.4.2
OS: Windows

Steps to reproduce:

1. Add a connection to a case sensitive sql server
2. Run telegraf

Expected behavior:

Rretrieve information on specified query below

Actual behavior:

Following query returns no rows on a case sensitive sql server:

SELECT 'Buffer pool rate (bytes/sec)', BufferPoolRate = (1.0cntr_value * 8 * 1024) /
(SELECT 1.0cntr_value FROM sys.dm_os_performance_counters WHERE object_name like '%Buffer Manager%' AND lower(counter_name) = 'Page life expectancy')
FROM sys.dm_os_performance_counters
WHERE object_name like '%Buffer Manager%'
AND counter_name = 'database pages'

Additional info:

Problem with lower and 'database pages' syntax.
This query is contained in sql server input plugin between rows 247 and 251

Proposal:

Replace this query:

SELECT 'Buffer pool rate (bytes/sec)', BufferPoolRate = (1.0cntr_value * 8 * 1024) /
(SELECT 1.0cntr_value FROM sys.dm_os_performance_counters WHERE object_name like '%Buffer Manager%' AND lower(counter_name) = 'Page life expectancy')
FROM sys.dm_os_performance_counters
WHERE object_name like '%Buffer Manager%'
AND counter_name = 'database pages'

By this one:

SELECT 'Buffer pool rate (bytes/sec)', BufferPoolRate = (1.0cntr_value * 8 * 1024) /
(SELECT 1.0cntr_value FROM sys.dm_os_performance_counters WHERE object_name like '%Buffer Manager%' AND counter_name = 'Page life expectancy')
FROM sys.dm_os_performance_counters
WHERE object_name like '%Buffer Manager%'
AND counter_name = 'Database pages'

Regards,
Valérian