Required fields on master search index

Question

We would like to inverse the logic and set the IndexAllFields property of the master index to false, so that only fields that are explicitly configured end up in the database. (Reason we are doing this has to do with the 1000 fields limit azure search)

Is there a list of fields that sitecore needs and should be added to the master index?

Answer 1

If you came here because you are using Azure Search on Sitecore 9 and are over 1000 fields, then you can safely set IndexAllFields to false, however at time of writing there is one known issue (ref 229445) preventing Forms from working correctly in 9.0.2 and below. To correctly patch your config:

<sitecore role:require="Standalone or ContentManagement or ContentDelivery" search:require="Azure">
<contentSearch>
  <indexConfigurations>
    <defaultCloudIndexConfiguration>
      <documentOptions>
        <!-- We only want default fields in the core/master/web indexes on azure due to 1000 field limit  -->
        <indexAllFields>false</indexAllFields>
        <!-- Fix sitecore 9 forms issue 229445 -->
        <include hint="list:AddIncludedField">
          <isTemplate>{558F9307-EBAF-480D-88B5-DFE9E63A66DE}</isTemplate>
          <hidden>{39C4902E-9960-4469-AEEF-E878E9C8218F}</hidden>
        </include>
      </documentOptions>
    </defaultCloudIndexConfiguration>
  </indexConfigurations>
</contentSearch>
</sitecore>

Note that this only works for Azure search. Lucene and Solr have other fields missing too - you'll have to raise a sitecore support ticket for those.

Answer 2

When you set IndexAllFields to false the indexing system will still index certain fields that it needs.

I recommend setting that value and then add a single field. Then in Azure Search review what fields are index so that you can see what gets indexed. It's only a few fields.