“About X results”: Sharepoint 2013 Search result counts keep changing

A question that’s asked fairly often is regarding the fact that Sharepoint Search seems to show inconsistent result counts from what is initially shown on the very first page and as you move along. Here is an example below:

About X results

Interestingly enough, this is pretty common for most search engines out there and I’ll start with showing a quick example of similar behavior with Google search. I’m going to run a search for “DocumentumConnector”, which you can see returns “About 13,000 results” on my first page.

DC_1

So what happens when I get to Page 10? There are now “About 12,800 results” shown, which means these numbers are just estimates and should get more precise as we move closer to the tail of the result set:

DC_2

Let’s get back to Sharepoint 2013 Search and explains what happens here. The “About x results” is presented when the total number of results is uncertain with Collapsing (i.e. duplicate detection in a typical case) enabled and the result set is partially processed.

  •  With TrimDuplicates = $true(it is by default), Sharepoint Search uses a default CollapseSpecification = “DocumentSignature”. This means we are collapsing on what are considered to be duplicate documents.
  •  Processing all of the results is too costly in terms of quickly returning results, which is why an estimate is given.

To recap, this means that a full result set isn’t processed for duplicates and the number returned as the Total number of hits after duplicate removal is an estimate based on how many duplicates were found in those results that were de-duplicated(based on collapsing done so far).

By default, your result page shows 10 results at a time. You may notice that for result sets with less than or equal to 10 results, you will always get an accurate number of results and thus “About” is omitted. For more than 10 results, you will get the “About x results” on the first page until you get to the very last page of results and only then we will actually know the exact number of results and can once again omit the “About”.

About Igor Veytskin

I have been working with Enterprise Search since 2005, ever since joining a company called FAST Search & Transfer. I'm currently working as a Premier Field Engineer with Microsoft, helping customers with large ESP, FS14 and Sharepoint 2013 implementations.
This entry was posted in FS4SP, SP2010, SP2013, Uncategorized and tagged , , , , , , , . Bookmark the permalink.

2 Responses to “About X results”: Sharepoint 2013 Search result counts keep changing

  1. I think the logic used in fs4sp where if you included say write or size as a refiner, the the total count got adjusted to this number which is more correct in many cases than the estimate.

    The issue though in 2013 is that refiner counts include duplicates. And a good reason to turn of the default duplicate, as the spec used gives too many false positives in my opinion.

    • Igor Veytskin says:

      Yes, and as we’ve discussed there are a few good reasons to turn off default duplicate trimming, I’m hoping a separate post coming soon describing how to influence duplicate detection in a supported way:).

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