From: David Bremner <david@tethera.net>
Date: Sat, 28 May 2022 10:32:08 +0000 (-0300)
Subject: discuss the "why not regex everywhere" question
X-Git-Url: https://git.cworth.org/git?p=notmuch-wiki;a=commitdiff_plain;h=b6429fa5333e6c8f474af784d6fd9f005c623d65

discuss the "why not regex everywhere" question
---

diff --git a/faq.mdwn b/faq.mdwn
index 92a2ef6..71c9ff8 100644
--- a/faq.mdwn
+++ b/faq.mdwn
@@ -69,6 +69,17 @@ searches. Punctuation is mostly ignored.
 The boolean prefix searches (see Boolean and Probabilistic Prefixes in the man
 page), such as tag: or path: searches, need an exact match.
 
+For [specific
+fields](https://notmuchmail.org/doc/latest/man7/notmuch-search-terms.html#search-prefixes)
+it is possible to use regex searches (although these are often
+noticeably slower than native Xapian queries). The limited set of
+fields is a quirk of implementation which requires a Xapian "value
+slot" in the database schema. Adding regex support for more fields to
+would require of adding more value slots to the schema. The
+performance impact of that needs to be experimentally evaluated, and
+assuming it is not too bad, some database upgrade code would need to
+be written.
+
 ## How do I search for folders or paths with spaces?
 
 The spaces in the names must be escaped. For example if you use bash or zsh,