diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index fca576cf9d..72a25b4f78 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -16,6 +16,7 @@ import shutil
 import sys
 import time
 import uuid
+from contextlib import suppress
 from functools import partial
 
 from calibre import as_unicode, force_unicode, isbytestring, prints
@@ -377,10 +378,23 @@ class Connection(apsw.Connection):  # {{{
         ans = self.cursor().execute(*args)
         if kw.get('all', True):
             return ans.fetchall()
-        try:
+        with suppress(StopIteration, IndexError):
             return next(ans)[0]
-        except (StopIteration, IndexError):
-            return None
+
+    def get_dict(self, *args, all=True):
+        ans = self.cursor().execute(*args)
+        desc = ans.getdescription()
+        field_names = tuple(x[0] for x in desc)
+
+        def as_dict(row):
+            return dict(zip(field_names, row))
+
+        if all:
+            return tuple(map(as_dict, ans))
+        ans = ans.fetchone()
+        if ans is not None:
+            ans = as_dict(ans)
+        return ans
 
     def execute(self, sql, bindings=None):
         cursor = self.cursor()
diff --git a/src/calibre/db/fts/pool.py b/src/calibre/db/fts/pool.py
index 356479d433..2a27f96aeb 100644
--- a/src/calibre/db/fts/pool.py
+++ b/src/calibre/db/fts/pool.py
@@ -62,12 +62,13 @@ class Worker(Thread):
             self.working = True
             try:
                 res = self.run_job(x)
-                if res is not None:
+                if res is not None and self.keep_going:
                     self.supervise_queue.put(res)
             except Exception:
                 tb = traceback.format_exc()
                 traceback.print_exc()
-                self.supervise_queue.put(Result(x, tb))
+                if self.keep_going:
+                    self.supervise_queue.put(Result(x, tb))
             finally:
                 self.working = False
 
diff --git a/src/calibre/db/tests/fts_api.py b/src/calibre/db/tests/fts_api.py
index 07d5ff2585..a6e4094f09 100644
--- a/src/calibre/db/tests/fts_api.py
+++ b/src/calibre/db/tests/fts_api.py
@@ -35,6 +35,9 @@ class FTSAPITest(BaseTest):
             while fts.all_currently_dirty() and time.monotonic() - st < timeout:
                 fts.pool.supervisor_thread.join(0.01)
 
+    def text_records(self, fts):
+        return fts.get_connection().get_dict('SELECT * FROM fts_db.books_text')
+
     def test_fts_pool(self):
         cache = self.init_cache()
         fts = cache.enable_fts()
@@ -43,6 +46,24 @@ class FTSAPITest(BaseTest):
         cache.add_format(1, 'TXT', BytesIO(b'a test text'))
         self.wait_for_fts_to_finish(fts)
 
+        def q(rec, **kw):
+            self.ae({x: rec[x] for x in kw}, kw)
+
+        def check(**kw):
+            tr = self.text_records(fts)
+            self.ae(len(tr), 1)
+            q(tr[0], **kw)
+
+        check(id=1, book=1, format='TXT', searchable_text='a test text')
+        # check re-adding does not rescan
+        cache.add_format(1, 'TXT', BytesIO(b'a test text'))
+        self.wait_for_fts_to_finish(fts)
+        check(id=1, book=1, format='TXT', searchable_text='a test text')
+        # check updating rescans
+        cache.add_format(1, 'TXT', BytesIO(b'a test text2'))
+        self.wait_for_fts_to_finish(fts)
+        check(id=2, book=1, format='TXT', searchable_text='a test text2')
+
     def test_fts_triggers(self):
         cache = self.init_cache()
         fts = cache.enable_fts(start_pool=False)