ColumnStore Monitor
ColumnStore Monitor
The ColumnStore monitor, csmon
, is a monitor module for MariaDB ColumnStore
servers. It supports multiple UM nodes and can detect the correct server for
DML/DDL statements which will be labeled as the master. Other UM nodes will be
used for reads.
Required Grants
The credentials defined with the user
and password
parameters must have all
grants on the infinidb_vtable
database.
For example, to create a user for this monitor with the required grants execute the following SQL.
CREATE USER 'maxuser'@'%' IDENTIFIED BY 'maxpwd'; GRANT ALL ON infinidb_vtable.* TO 'maxuser'@'%';
Master Selection
The automatic master detection only works with ColumnStore 1.2. Older versions of ColumnStore do not implement the required functionality to automatically detect which of the servers is the primary UM.
With older versions the primary
parameter must be defined to tell the monitor
which of the servers is the primary UM node. This guarantees that DDL statements
are only executed on the primary UM.
Configuration
Read the Monitor Common document for a list of supported common monitor parameters.
primary
The primary
parameter controls which server is chosen as the master
server. This is an optional parameter.
If the server pointed to by this parameter is available and is ready to process
queries, it receives the Master status. If the parameter is not defined and
the ColumnStore server does not support the mcsSystemPrimary
function, no
master server is chosen.
Note that this parameter is only used when the server does not implement the required functionality. Otherwise the parameter is ignored as the information from ColumnStore itself is more reliable.
Example
The following is an example of a csmon
configuration.
[CS-Monitor] type=monitor module=csmon servers=um1,um2,um3 user=myuser passwd=mypwd monitor_interval=5000 primary=um1
It defines a set of three UMs and defines the UM um1
as the primary UM.