Question

In DigitalOcean DBaaS service in MySQL log_replica_updates is set to ON

Posted on April 23, 2024
Managed Databases DigitalOcean Managed MySQL Database
Asked by Sid m

I set up a master and a read-only MySQL database using DigitalOcean’s DBaaS service and subjected it to heavy write loads. I noticed that the “Seconds Behind Master” metric increased significantly. Specifically, during a 300-second period of data insertion on a replica node with 2 cores and 4 GB of RAM, CPU utilization reached 100%. The lag times were approximately 1500 seconds with an insertion rate of 7,000 records per minute, and 250 seconds with a rate of 2,000 records per minute.

I observed that the ‘log-slave-updates’ parameter was enabled. From my past experience, this setting tends to significantly impact replication lag. Although the retrieved GTID remained in sync with the master, the executed GTID lagged behind. I’m curious about the rationale behind DigitalOcean’s default choice to enable this parameter. Could there be a specific reason why it is not set to ‘OFF’?

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Bobby Iliev

Site Moderator

• April 23, 2024

Hey @sidm,

My guess here would be that this is enabled by default for data consistency and recovery scenarios because it allows standby nodes to be promoted to a primary node without losing any data:

https://docs.digitalocean.com/glossary/standby/

But if you believe that this is unnecessary, the best thing to do to get your voice heard regarding this would be to head over to our Product Ideas board and post a new idea, including as much information as possible for what you’d like to see implemented.