Less database-heavy operations - every keyword operation uses the table indexes, therefore no full table lookup, nor temporary tables are needed.
CAN index shortcode contents!
Indexes selected PODs custom fields contents, that connect to a custom table
Good for big databases
Better relevancy calculation
Can't search for exact matches - the index table consists of separated keywords with relational and relevancy data. There is no way of determining the sorrounding keywords, therefore exact matching is not possible.
Can't search word inner parts, only beginnings and endings
for example "rat" NOT match "karate"
but "kar" will match "karate"
and "rate" will match "karate"
Has to be configured before use.
Only one index configuration for every search instance
Should I use the index table engine?
Short answer, yes, you should. You definitely should if you:
Want to search shortcode content
Want to search tags, categories or any terms related to posts
Custom fields content
Have a big database of posts
Which type of content can be indexed?
You can index posts, pages and any custom post type. (products, forums, topics, etc..)