In the content table of an Ektron database you will see a content_text and a content_html column. The content_html is used when displaying the content in a browser, but what is the content_text used for? 

Content_text is the text crawled by Ektron search providers such as Solr and Microsoft Search Server. Other columns are crawled as well, but only content_text is searched by the keyword search. Other properties such as metadata can be searched using expression trees. For more on querying, see the following document. 

Search API