MariaDBintermediate

MariaDB Monitoring

MariaDB-specific status variables and statistics tables, including Galera cluster health.

2 min readIntermediateUpdated 31 Jul 2026Edit this page

The InnoDB and query metrics in MySQL Monitoring apply. This page covers what is specific to MariaDB.

User and index statistics

MariaDB's userstat feature has no direct MySQL equivalent and is the easiest way to find unused indexes and noisy clients:

userstat = 1

-- Indexes never used since the last restart.
SELECT s.table_schema, s.table_name, s.index_name
FROM information_schema.statistics s
LEFT JOIN information_schema.index_statistics i
  ON i.table_schema = s.table_schema
 AND i.table_name = s.table_name
 AND i.index_name = s.index_name
WHERE i.index_name IS NULL
  AND s.table_schema NOT IN ('mysql','information_schema','performance_schema')
  AND s.index_name <> 'PRIMARY';
 
-- Which clients generate the load.
SELECT user, total_connections, rows_read, rows_sent, busy_time
FROM information_schema.user_statistics ORDER BY busy_time DESC;
 
-- Which tables are actually read and written.
SELECT table_schema, table_name, rows_read, rows_changed
FROM information_schema.table_statistics ORDER BY rows_read DESC LIMIT 20;

Galera cluster health

For a Galera deployment these are the metrics that matter most:

wsrep_cluster_status

Source: SHOW STATUS

Must be Primary. non-Primary means this node has lost quorum and is not serving.

wsrep_cluster_size

Source: SHOW STATUS

Number of members. Alert on any change — a silent drop from 3 to 2 removes your failure tolerance.

wsrep_local_state_comment

Source: SHOW STATUS

Should be Synced. Donor/Desynced or Joining means the node is transferring state and is not serving normally.

wsrep_flow_control_paused

Source: SHOW STATUS

Fraction of time the cluster was throttled by a slow member. Sustained non-zero values mean one node is limiting everyone.

wsrep_local_recv_queue_avg

Source: SHOW STATUS

Average apply queue on this node. Consistently above zero identifies the lagging member.

wsrep_local_cert_failures

Source: SHOW STATUS

Certification conflicts. Rising values mean the same rows are being written from several nodes.

Slow query log

MariaDB adds detail levels the MySQL log does not have:

slow_query_log = 1
long_query_time = 0.5
log_slow_verbosity = query_plan,explain

log_slow_verbosity = explain records the query plan alongside the slow statement, which removes the guesswork of reproducing it later.

Exporters

mysqld_exporter works with MariaDB, but some collectors query MySQL-specific tables and will fail or return nothing. Verify each enabled collector against your MariaDB version, and add the Galera status variables explicitly if you run a cluster. See Prometheus Monitoring.