With the default engine, the search logic works on a field basis – meaning that each keyword must match at least one of the selected fields. In case of “breakfast eggs sunday”, each word will have to match either the title, content or any of the selected fields. If the title matches “eggs” the content matches “breakfast” and “sunday”, it's not considered as a match – because on database level this is not possible to distinguish.
To resolve this limitation and optional Index Table engine was implemented to index posts and post_type object contents. You will find all the information and explanations on these documentation chapters:
– Index table introduction
– Generating an index table
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