MemDB collects statistics under the
MemDB-Local parameter sets, within each data stripe.
They can be monitored on a per-stripe basis, or viewed as an aggregate across all stripes.
The parameter set names of the per-stripe statistics end with suffix of the form
For example, the stats for the first stripe will have suffix
MemDB maintains atomicity, consistency and isolation of data across stripes.
This involves managing the versions of data exposed to various client transactions.
MemDB-Timestamp parameter set contains the relevant statistics.
This is a listing of the statistics available for a particular MemDB instance, within the
MemDB-Timestamp parameter set:
Counter type statistics: Id: Name: Label: Description: 0 waitingThreads waiting The number of threads waiting for a timestamp to become safe 1 unexposedCommits unexposed The number of commits which are not yet safe to expose
A database transaction containing at least one write is considered "safe to expose to client transactions" when (as shown by these statistics) all its changes — as well as all the write transactions that precede them — are available across all stripes.
|These statistics are expected to have low values even under load (often with value zero), and should stay at zero when Rhino is not under load.