# Mnesia Collector Collects Mnesia metrics mainly using [:mnesia:system_info/1](http://erlang.org/doc/man/mnesia.html#system_info-1). ## Exported metrics

```
erlang_mnesia_held_locks
```
Type: gauge.
Number of held locks.
```
erlang_mnesia_lock_queue
```
Type: gauge.
Number of transactions waiting for a lock.
```
erlang_mnesia_transaction_participants
```
Type: gauge.
Number of participant transactions.
```
erlang_mnesia_transaction_coordinators
```
Type: gauge.
Number of coordinator transactions.
```
erlang_mnesia_failed_transactions_total
```
Type: counter.
Number of failed (i.e. aborted) transactions.
```
erlang_mnesia_committed_transactions_total
```
Type: gauge.
Number of committed transactions.
```
erlang_mnesia_logged_transactions_total
```
Type: counter.
Number of transactions logged.
```
erlang_mnesia_restarted_transactions_total
```
Type: counter.
Total number of transaction restarts.

## Configuration Metrics exported by this collector can be configured via `mnesia_collector_metrics` key of `prometheus` app environment. Available options: - `:held_locks` for `erlang_mnesia_held_locks`; - `:lock_queue` for `erlang_mnesia_lock_queue`; - `:transaction_participants` for `erlang_mnesia_transaction_participants`; - `:transaction_coordinators` for `erlang_mnesia_transaction_coordinators`; - `:transaction_failures` for `erlang_mnesia_failed_transactions_total`; - `:transaction_commits` for `erlang_mnesia_committed_transactions_total`; - `:transaction_log_writes` for `erlang_mnesia_logged_transactions_total`; - `:transaction_restarts` for `erlang_mnesia_restarted_transactions_total`. By default all metrics are enabled.