X-Git-Url: https://git.cworth.org/git?a=blobdiff_plain;f=faq.mdwn;h=71c9ff80e6a06fc9b367031b12c4cb678fb06a27;hb=b6429fa5333e6c8f474af784d6fd9f005c623d65;hp=2e7fa10a03424e80f43493122931f9c295e8c0b9;hpb=ac34b9b44bcc8693030be54b09885f51433c6bdd;p=notmuch-wiki

diff --git a/faq.mdwn b/faq.mdwn
index 2e7fa10..71c9ff8 100644
--- a/faq.mdwn
+++ b/faq.mdwn
@@ -27,7 +27,7 @@ See [[excluding]].
 
 See help for `message-citation-line-format` for details.
 
-## What are sexp queries
+## What are sexp queries?
 
 For the syntax of sexp queries, see [the manual
 page](https://notmuchmail.org/doc/latest/man7/notmuch-sexp-queries.html).
@@ -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,