KV store stats

These provide various low-level stats and timings from the underlying KV storage system and useful to understand various states of the storage system.

The following stats are available for all database engine:

Stat Description
open Number of database open operations
close Number of database close operations
readTime Time spent in read operations
readSize Size of data in read operations
writeTime Time spent in write operations
writeSize Size of data in write operations
delete Time spent in delete() calls

The following stats are available for the CouchStore database engine:

Stat Description
backend_type Type of backend database engine
commit Time spent in CouchStore commit operation
commitRetry Time spent in retry of commit operation
numLoadedVb Number of Vbuckets loaded into memory
numCommitRetry Number of commit retry
lastCommDocs Number of docs in the last commit
failure_set Number of failed set operation
failure_get Number of failed get operation
failure_vbset Number of failed vbucket set operation
save_documents Time spent in CouchStore save documents operation