ProxySQL 2.x.x and Percona Scheduler Admin tool¶
ProxySQL 2.3.2-1.2 adds the Percona Scheduler Admin (percona-scheduler-admin) tool. This tool has a segment-aware failover mechanism and can automatically perform a failover due to node failures, service degradation, or maintenance requirements. The external scheduler has the following qualities:
-
Capable of parallel query execution on nodes which results in faster failover or fallback
-
Supports fallback
-
Supports promoting a reader to primary with the following conditions are met:
-
wsrep_on=OFF
-
wsrep_sst_donor_rejects_queries is set when, for example, connections are rejected due to an ongoing state transfer
-
Supports a retry of operations in case of network glitches
Important
Percona Scheduler Admin was built for a different purpose and has different features than proxy-admin. You cannot use the options from one admin tool in the other admin tool. Combining the options causes unintended results.
Version changes¶
The Percona Scheduler Admin tool has been tested with ProxySQL 2.3.0, 2.3.2-1.2, and later versions.
ProxySQL 2.4.2 add the following checks:
When pxc_scheduler_handler launches, the application creates a lock file to prevent the running of multiple instances. Prior to ProxySQL 2.4.2, the lock file remained in the file system and prevented the handler script from running.
Starting with ProxySQL 2.4.2, on startup, pxc_scheduler_handler does the following:
* Reads the Process identifier (PID)
* Reads the timestamp from the lock file
* Checks if the PID is running on startup
If the PID is running, the newly launched pxc_scheduler_handler exits.
If the PID is not running, the pxc_scheduler_handler checks the lockFileTimeout timeout value. If the timeout value has been exceeded, the pxc_scheduler_handler removes the lock file and launches pxc_scheduler_handler.
Prerequisites¶
The following are the prerequisites for using the Percona Scheduler Admin:
-
The mysql command-line client and my_print_defaults must be installed on the system. Install the server packages on the system to add these tools.
-
ProxySQL and Percona XtraDB Cluster are running.
For information on the Percona Scheduler Admin tool installation, see Install ProxySQL 2.x.x and the admin utilities or Build the Percona Scheduler admin tool.
Add an issue¶
If you find a Percona Scheduler Admin bug, add a bug report in the PSQLADM project.
