Details
Major Description
Abseil has some recommendations about efficiently using re2 here: https://abseil.io/fast/21
One recommendation it has is to avoid leading / trailing .* for FullMatch():
Using RE2::FullMatch() with leading or trailing .* is an antipattern. Instead, change it to RE2::PartialMatch() and remove the .*. RE2::PartialMatch() performs an unanchored search, so it is also necessary to anchor the regular expression (i.e. with ^ or $) to indicate that it must match at the start or end of the string.
For our slow path LIKE evaluation, we convert the LIKE to a regular expression and use FullMatch(). Our code to generate the regular expression will use leading/trailing .* and FullMatch for patterns like '%a%b%'. We could try detecting these cases and switching to PartialMatch with anchors. See the link for more details about how this works.