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Index integrated solution

Describes the indexing of an integrated solution with Optimizely Search & Navigation and Optimizely Content Management System (CMS).

Because you reference the EPiServer.Find.Cms assembly in the Optimizely Content Management System (CMS) project, published content is automatically indexed. Content is also reindexed, or deleted from the index, when it is saved, moved or deleted. Each language version is indexed as a separate document.

Indexing module

The indexing module is an IInitializableModule that handles all DataFactory event indexing. Whenever content is saved, published, moved or deleted, it triggers an index request to the ContentIndexer.Instance object, which handles the indexing.


The ContentIndexer.Instance singleton, located in the EPiServer.Find.Cms namespace, adds support for indexing IContent and UnifiedFile objects. ContentIndexer.Instance supports re-indexing the entire PageTree and specific language branches and individual content and files. When indexing an IContent object, all page files are also indexed.

Invisible mode

A core feature of the ContentIndexer is its ability to work in invisible mode when indexing objects passed by the IndexingModule. In invisible mode, indexing is handled in a separate thread, not the DataFactory event thread. So, indexing does not delay the DataFactory event thread and, therefore, does not delay the save/publish action. To override this default behavior, set ContentIndexer.Instance.Invisible to false.


The ContentIndexer.Instance has conventions for customizing indexing. For example, you can control which pages are indexed (described below) and dependencies between pages.

Customize pages to be indexed

To control which content is indexed, pass a verification expression to the ShouldIndex convention. By default, all published content is indexed.

For example, if you do not want to index a page type (such as the LoginPageType), pass a verification expression that validates to false for the LoginPageType to the ShouldIndex convention. Preferably, you would do this during application startup, such as in the global.asax file's Application\_Start method.

//using EPiServer.Find.Cms.Conventions;

  .ShouldIndex(x => false);

To override the default setting, add a convention for PageData and add the appropriate verification expression.

//using EPiServer.Find.Cms.Conventions;
  .ShouldIndex(x => true);

To exclude a property from being indexed, use the JsonIgnore attribute or add a convention for it.

//using EPiServer.Find.Cms.Conventions;
  .ExcludeField(x => x.ACL);
public DateInterval Interval { get; set; }

File indexing

Using IContentMedia, files are indexed by default when based on the following MIME types:

  • "text/plain"
  • "application/pdf"
  • "application/postscript"
  • "application/msword"
  • "application/vnd.openxmlformats-officedocument.wordprocessingml.document"

Manage PII in search results

You should not index form attachments if there is a chance those attachments contain sensitive information, such as personally identifiable information (PII). For example, if you upload documents with PII data on form attachments, Optimizely Search & Navigation will index these, even though form attachment permissions prevent viewing. However, the information might be discovered in search results.

To prevent this, add the following initialization code to prevent uploads of those form attachments.

    public class FindInitialization : IInitializableModule
        private ContentAssetHelper contentAssetHelper; 
        private ContentIndexer contentIndexer; 

        public void Initialize(InitializationEngine context)

            contentAssetHelper = ServiceLocator.Current.GetInstance<ContentAssetHelper>();
            contentIndexer = ServiceLocator.Current.GetInstance<ContentIndexer>();            
            ContentIndexer.Instance.Conventions.ForInstancesOf<MediaData>().ShouldIndex(p => ShouldIndexDocument(p));


        bool ShouldIndexDocument(MediaData content)
            if (contentAssetHelper.GetAssetOwner(content.ContentLink) is FileUploadElementBlock)
                //if descendant of episerver forms or a file uplaoded through a epi form, do not index
                return false;
            return !content.IsDeleted && isNotArchived(content.StopPublish);

        bool isNotArchived(DateTime? stopPublishDate )
            return (stopPublishDate == null || (stopPublishDate != null && stopPublishDate > System.DateTime.Now));

        public void Uninitialize(InitializationEngine context)

Change the name or namespaces of page types

If you change the name or namespace of a page type, a mismatch occurs between types in the index and the new page types. This might cause errors when querying, because the API cannot resolve the correct page type from what is reported from the index. To solve this, reindex all pages, using the scheduled plugin, to have new page types reflected in the index.

Improve search relevancy for attachments

By default, search relevancy for text inside an attachment is imperfect. This is because attachments are indexed in the default language, which might not match the document's content. CMS content, in contrast, is indexed using all enabled languages to improve search relevancy.

Also, when browsing Search & Navigation's explore view of an attachment, the attachment text is not readable, because it is indexed using the base64 representation of itself.

To improve the search relevancy of text attachments, use the IAttachmentHelper interface, which enables developers to implement their own parsing of attachments. Out of the box, Optimizely provides an implementation of IAttachmentHelper that uses Microsoft IFilter functionality. For this to work, the correct IFilters need to be installed on the client.

Optimizely highly recommends using this package, as it enhances the quality of your search.

Use the default implementation of IAttachmentHelper

  1. Install the EPiServer.Find.Cms.AttachmentFilter NuGet package.
  2. Determine which attachment file types you want to support (for example, PDF and Microsoft Word). Each file type has a corresponding filter. The list of file types and filters is below.
  3. Download and install the selected filters.
  4. Restart.
  5. Add some supported file attachments to your site.
  6. Log into your website and browse to Find > Overview > Explore.
  7. Find the attachments and verify that their content is stored as readable text under SearchAttachmentText$$String.

Supported file formats

Using Ifilters with Search & Navigation, you can parse the file types below.

File types: adw, ai, doc, docm, docx, dwg, eps, gif, html, htm, jpeg, jpg, mm, msg, odt, ods, odp, odi, one, otf, otp, pdf, png, ppt, pptm, pptx, ps, rar, sda, sdg, sdm, sfs, sgf, smf, std, sti, stw, svg, sxd, sxi, txt, vdx, vsd, vdx, vor, vss, vst, vsx, vtx, wma, wmv, xls, xlsb, xlsm, xlsx, xml, zip

For many file types, more than one filter is available. You can find more filters for example on IFilterShop.

Some common file types and their filters are listed below.


Adobe has the PDF IFIlter, although it does not work in all environments. 

Microsoft Office 2010 filter packs

Microsoft's filter pack (download here) covers the file types below.

  • Legacy Office Filter (97-2003; .doc, .ppt, .xls)
  • Metro Office Filter (2007; .docx, .pptx, .xlsx)
  • Zip Filter
  • OneNote filter
  • Visio Filter
  • Publisher Filter
  • Open Document Format Filter

String length indexing limitation

In the underlying functionality for Optimizely Search & Navigation, there is an ignore_above Elasticsearch parameter which is set to "8191". The value is the quote of the maximum limit of bytes per term in Lucene, and the maximum number of bytes per UTF-8 character, minus one  ((32766/4)-1) = 8191).

If a string field is longer than ignore_above, it will not be indexed or stored. This setting cannot be modified.

Related blog post: Why is my Find indexing job freezing and dying?