How to use ndb_read_backup and read from backup replica

(Doc ID 2351956.1)

Last updated on JANUARY 30, 2018

Applies to:

MySQL Cluster - Version 7.5 and later
Information in this document applies to any platform.


Beginning with MySQL Cluster 7.5.2, it is possible to enable reads from any replica. This is disabled by default but can be enabled for a given SQL node using the ndb_read_backup system variable added in this release. Previously, all reads were directed towards the primary replica except for simple reads. (A simple read is a read that locks the row while reading it.)

This document describes the steps required to utilize this feature.



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