RavenDB Query Correct Results After Second Attempt

Question

When my C#, WPF UI starts, one of the tabs calls this code when loading. The most recent data displayed is 11-Feb-2012, even though there are InstallationSummary documents for 15-Feb-2012. When I hit the refresh button, this exact same code is called, only this time the most recent results are displayed. How can the same code produce two different results?

IQueryable<EntityBase> installationSummaries =
  QueryAndSetEtags(session => session.Query<InstallationSummary>()
  .Include(x => x.ApplicationServerId)
  .Include(x => x.ApplicationWithOverrideVariableGroup.ApplicationId)
  .Include(x => x.ApplicationWithOverrideVariableGroup.CustomVariableGroupId)
  .OrderByDescending(summary => summary.InstallationStart)
  .Take(numberToRetrieve));

Note: I'm having the exact same issue with another query. It seems as if I haven't queried in a while, I get the incorrect results. If I query again right after I just did it, I get the right results. I'm wondering if I have to create an index. There are over 10,000 InstallationSummary documents, and the performance is just fine. It's the accuracy that I'm having trouble with.

Answer 1

Sounds like a stale index issue. Try to add this line and see if that helps

.Customize(x => x.WaitForNonStaleResultsAsOnNow())

Update: It is better to use WaitForNonStaleResultsAsOnNow() than WaitForNonStaleResults()

Edit: Why is that?
The reason is, that your query will create a temporary index that automatically will be deleted after some time of inactivity. Further, they will not survive a restart of RavenDB. Now you have a few option:

• promote the index to be permanent using the management studio

• create an index within your application and use that index when querying

• wait for raven to self optimize itself and promote the index automatically (this will only happen if the query will be run often enough, which seems unlikely in your case)

• use the .WaitForNonStaleResuls() option as outlined above (this is worst because it can have a very negative impact on application performance and there's no need to because the other options are much better)