SHOW REPLICATION STATUS

Shows the list of all connections between the replication master and slave databases.

Syntax

SHOW REPLICATION STATUS

Remarks

  • The URI identifies the database as <host>:<port>/<dbName>.
  • Log position is the position in the transactional log formatted as <LogFileId>:<ByteOffsetInLogFile>.
  • Each database in slave-replication mode has two background threads (SlaveNetwork and SlaveReplay). The state and position of both slave threads are displayed per-database. The SlaveNetwork thread downloads the necessary snapshot files and transaction logs from the master database and the SlaveReplay thread reads transactions from these files and commits them to memory.
  • This command can be run on any MemSQL node (see Node Requirements for MemSQL Commands).
  • If a sync replication slave is out of sync it will not appear in the output.
  • This command does not display DR clusters and the master databases that do not have slaves.

Output

Column Explanation
Role The replication role of the local database copy. Possible values are async slave, sync slave, and master.
Database The name of the database being replicated. The database name is the same on the primary and secondary clusters, except for the sharding database which is called sharding_[hash] on the secondary cluster.
MasterURI The URI for the master database instance. The format is host:port/database_name.
Master_State The state of the master database instance. Commonly, the master state is online but differs during transition periods/errors. See Database States for details.
Master_CommitLSN Position in the log before which all pages have been committed. All content is committed in the pages that are in the log before this log sequence number (LSN).
Master_HardenedLSN Position in the log before which all pages have been written to the disk.
Master_ReplayLSN Position in the log before which all pages have been replayed into memory.
Master_TailLSN Position in the log before which all pages have been reserved for transactions. The next transaction to reserve space from the log will start writing at this LSN.
MasterCommits The number of transactions committed on the master database instance.
Connected The current state of the connection between master and slave instances of the database. Possible values are yes and no.
SlaveURI The URI for the slave database instance. The format is host:port/database_name.
SlaveState The state of the slave database instance. Possible values are replicating and replication paused.
Slave_CommitLSN Position in the log before which all pages have been committed. It is replicated from the master, and thus is expected to be behind Master_CommitLSN.
Slave_HardenedLSN Position in the log before which all pages have been written to the disk.
Slave_ReplayLSN Position in the log before which all pages have been replayed into memory. It is always less than or equal to CommitLSN (in an active workload, it is expected to lag behind CommitLSN by few LSN).
Slave_TailLSN All pages that have been received from the master is below this LSN.
SlaveCommits The number of transactions committed on the slave database instance.
Info

This MemSQL feature is only available in MemSQL Enterprise Edition. MemSQL Enterprise Edition includes 24x7 support and several enterprise-only features for critical deployments. For more information about MemSQL Developer and MemSQL Enterprise, see the MemSQL Editions page.

Example

memsql> SHOW REPLICATION STATUS;
****
+--------+----------+------------+--------------+------------------+--------------------+------------------+----------------+----------------+-----------+------------+------------------------+-------------+-----------------+-------------------+-----------------+---------------+---------------+
| Role   | Database | Master_URI | Master_State | Master_CommitLSN | Master_HardenedLSN | Master_ReplayLSN | Master_TailLSN | Master_Commits | Connected | Throttling | Slave_URI              | Slave_State | Slave_CommitLSN | Slave_HardenedLSN | Slave_ReplayLSN | Slave_TailLSN | Slave_Commits |
+--------+----------+------------+--------------+------------------+--------------------+------------------+----------------+----------------+-----------+------------+------------------------+-------------+-----------------+-------------------+-----------------+---------------+---------------+
| master | cluster  | NULL       | online       | 0:239            | 0:239              | 0:233            | 0:239          |             32 | yes       | no         | 127.0.0.1:3307/cluster | replicating | 0:238           | 0:239             | 0:238           | 0:239         |            30 |
| master | trades   | NULL       | online       | 0:4294967341     | 0:4294967341       | 0:4294967339     | 0:4294967341   |             39 | yes       | no         | 127.0.0.1:3307/trades  | replicating | 0:4294967340    | 0:4294967341      | 0:4294967340    | 0:4294967341  |            38 |
+--------+----------+------------+--------------+------------------+--------------------+------------------+----------------+----------------+-----------+------------+------------------------+-------------+-----------------+-------------------+-----------------+---------------+---------------+