When searching for more than 4-5 words in Confluence even when this sentence is part of the document results are not accurate. Also when ' is added to before any word the results are not accurate.

For example:

Searching for "My SQL Default Slave Behind for more than 12 hours on weekend" does not show as the first result which would be more accurate matching the search and document. See picture attached.

I ran some tests and when you add more and more words Confluence search tends to not return 100% accurate.