Recently worked on dashboard tab can be slow on SQL Server 2014

Steps to reproduce

• Set up Confluence 6.6.7 with a SQL Server 2014 v12.0.5589 database (may affect other versions of SQL Server as well)
• Populate the database with data with dimensions similar to this:
  • Over 2 million rows in the content table
  • At least one user with ~10,000 documents or versions of documents modified
• Visit the recently worked on tab in the dashboard

Expected results

Dashboard tab loads in a timely manner.

Actual results

Dashboard tab never loads. The database CPU spikes for a long time and the query takes about 30 minutes to return. Due to the database being so busy this can cause stability issues causing the rest of Confluence to stop working as well.

Workaround

The best workaround at the moment is to disable the feature. This involves 2 steps:

1. Modify your reverse proxy settings to block requests to the search endpoint when the any requests matching this pattern is issued:

   /rest/api/content/search\?.*recentlyModifiedPagesAndBlogPostsByUser.*

   Unfortunately there is no way to do this within Tomcat or Confluence itself.

2. Add the following CSS to remove the link from the dashboard:

   .confluence-dashboard li.nav-item-container-recently-worked {
       display: none;
   }