What does the sys.dm_exec_query_optimizer_info "timeout" record indicate?

Question

During an investigation of some client machines losing their connection with SQL Server 2005, I ran into the following line of code on the web:

Select * FROM sys.dm_exec_query_optimizer_info WHERE counter = 'timeout'

When I run this query on our server - we are getting the following results:

counter - occurrence - value

timeout - 9100 - 1

As far as I can determine, this means that the query optimizer is timing out while trying to optimize queries run against our server – 9100 times. We are however, not seeing any timeout errors in the SQL Server error log, and our end-users have not reported any timeout specific errors.

Can anyone tell me what this number of “occurrences” means? Is this an issue we should be concerned about?

Answer 1

The occurence column will tell you the number of times that counter has been incremented and the value column is an internal column for this counter.

See here

Answer 2

Sorry, the documentation say this is internal only.

Based on the other link, I suspect this is for internal engine timeouts (eg SET QUERY_GOVERNOR_COST_LIMIT)

A client timeout will also not be logged in SQL because the client aborts the batch, ths stopping SQL processing.

Please do you have more details?