Excessive updates of the EventQueue table

Question

We are using Sitecore 7.2 and Coveo for sitecore in our multilingual CMS website. Our sitecore really gets slow sometimes and we could also see deadlocks happening in our application logs.

Upon analysis, We could see that there are almost 300000 records getting added in our EventQueue table of Core database. Sitecore recommends to have less than 1000 rows in EventQueue table.

Current CleanupEventQueue task is set to Run every 4 hours to remove the entries which are older than a day and so EventQueue table does not contain any entries older than a day.

We found that Property changed event is getting triggered for every coveo index last updated field change and due to this,a large number of row entries are added to the EventQueue table. This constitutes to almost 60% of the rows in the EventQueue table.

EventType : Sitecore.Data.Eventing.Remote.PropertyChangedRemoteEvent, Sitecore.Kernel, Version=7.0.0.0, Culture=neutral, PublicKeyToken=null

We followed the sitecore recommendation based on the article https://kb.sitecore.net/articles/930920 and added the required configs and library files. Even after adding the recommendation, we could not see the count of EventQueue rows getting reduced.

Can you please let me know if I am missing something.

Thanks, Karthik

Answer 1

Every time an index update operation occurs, an index update timestamp is written to the Property table of the core database. This is a known issue related to this behavior.

This happens because Sitecore Content Search uses the Properties database table for storing instance specific search indexes metadata. For example, it stores the time of the last index update. Each change to the Properties table leads to PropertyChangedRemoteEvent being recorded to the EventQueue table to notify other connected Sitecore instances to update their caching layer around the Properties table. If the index updates are frequent enough, the aforementioned behavior may lead to excessive cache repopulation, and subsequent performance issues on both Content Management and Content Delivery servers.

Solution 1

As one of the options to address the issue, it is possible to implement the following solution:

1. Apply the patch from the Modification of the Properties table does not respect EventDisabler article.

2. Place the Sitecore.Support.417664.dll assembly to the /bin folder.

3. Place the Sitecore.Support.DatabasePropertyStore.417664.config file to the /App_config/Include folder.

   For Sitecore 7.0 - 7.2: Sitecore.Support.DatabasePropertyStore.417664.config

   For Sitecore 7.5 and later: Sitecore.Support.DatabasePropertyStore.417664.v2.config

Patch details:

Because the information recorded by Sitecore Content Search using the Properties table is instance-specific, there may be no need in sharing the property change events among other Sitecore instances. The current patch uses EventDisabler to prevent excessive population of the EventQueue table.

Second solution you can find it here: https://kb.sitecore.net/articles/930920