Always worth a mention: https://use-the-index-luke.com/ https://use-the-index-luke.com/ Markus Winand (the website's author) has also written a book on the su

Always worth a mention: https://use-the-index-luke.com/ https://use-the-index-luke.com/ Markus Winand (the website's author) has also written a book on the subject targeted at software developers which is decent for non-DBA level knowledge.