I'm hoping someone can give me some more information on either of these two wait types PWAIT_MD_RELATION_CACHE and MD_LAZYCACHE_RWLOCK. We started seeing these happen on queries that were accessing a table with 1,000 records, most of the waits were over a couple minutes. No blocking was occurring at the time, and other queries against the database were able to complete successfully.
From doing a bit of research I was able to find this description on MSDN for PWAIT_MD_RELATION_CACHE: "Occurs during internal synchronization in metadata on table or index." This made me believe the issues was revolving around a large insert, update or delete that was occurring during that time, or manipulation of an index on the table. No records had been inserted or updated in the last 3 days, the indices were last rebuild 2 days prior to the issue.
I've been unable to find anything in relation to MD_LAZYCACHE_RWLOCK.
We are currently running Microsoft SQL Server 11.0.2100.60.
Any help or ideas would be appreciated.