SQL Replication doesn't clear CD caches on remote target

Question

We have a multi-cd publishing situation I can use some help with.

We are in an Azure PAAS situation, with the CM and 1 CD server located in the US. We also have a CD Server and SQL database in China (using Azure China/21 Vianet). Due to the fault tolerance, we decided to use replication to move the data to China. So we set up a publishing target in the US called web_china and can publish to that database. We then use replication to copy the data from the US to China.

The issue is that the replication can take up to 5 minutes and by that time the publish:end:remote event has already been processed by the China CD server. So even though the data is in the web_china database in China, due to caching (?) the changes are not visible. If we publish the item a second time (since it is already in China), it appears on the site.

I have tried to add a task that runs in China and clears the cache on a regular basis. It clears both the Html Cache, MVC Cache, and Rendering Parameters Cache. However, even after running, the item is not visible in China. I then tried to delete all Caches, but that brought the site to a grinding halt.

Is there another cache that I should clear to get the published changes to show up?

Or is the better idea to just convert to using Publishing Service, which is a much more fault-tolerant process.

Answer 1

A great, fast supported way is documented here using Azure SQL Geo Replication. The idea is:

• The Sitecore Web DB is put in a geo replication group
• You need a new "Shared" DB that all Sitecore instances connect to - purely for the Event Queue, Properties, and Tasks tables.
• This way your content data is replicated with the power of Azure SQL, but cache clearing and other events can still happen.