From f82c115b0e1a4cc30c2ee7c0a969402b7fd3eebf Mon Sep 17 00:00:00 2001
From: Frederick Muriuki Muriithi
Date: Thu, 30 Mar 2023 09:16:23 +0300
Subject: Gotchas: Pure `NOT` queries not supported

Add a section in the documentations about things that are not entirely
obvious to the user when doing search.
---
 topics/xapian-search-queries.gmi | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

(limited to 'topics')

diff --git a/topics/xapian-search-queries.gmi b/topics/xapian-search-queries.gmi
index 0364344..74966f7 100644
--- a/topics/xapian-search-queries.gmi
+++ b/topics/xapian-search-queries.gmi
@@ -90,3 +90,25 @@ Alternatively, this same query may be expressed using kilo or mega suffixes.
 Hs:chr4:9130k..9980k species:mouse
 Hs:chr4:9.13M..9.98M species:mouse
 ```
+
+## Gotchas
+
+### Pure `NOT` queries are not supported
+
+Due to
+=> https://xapian.org/docs/apidoc/html/classXapian_1_1QueryParser.html#ae96a58a8de9d219ca3214a5a66e0407eacafc7c8cf7c90adac0fc07d02125aed0 performance reasons,
+pure `NOT` queries are not supported.
+
+A search such as:
+
+```
+NOT author:hager
+```
+
+will fail.
+
+You will need to add something to the query to prevent the error, e.g.
+
+```
+species:mouse NOT author:hager
+```
-- 
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