perf: Optimize searching tags with DB indexes

src/tagstudio/core/library/alchemy/library.py

@@ -9,6 +9,7 @@
 
 import re
 import shutil
+import sys
 import time
 import unicodedata
 from collections.abc import Iterable, Iterator
@@ -75,7 +76,6 @@
     DB_VERSION_LEGACY_KEY,
     JSON_FILENAME,
     SQL_FILENAME,
-    TAG_CHILDREN_QUERY,
 )
 from tagstudio.core.library.alchemy.db import make_tables
 from tagstudio.core.library.alchemy.enums import (
@@ -555,6 +555,20 @@ def open_sqlite_library(self, library_dir: Path, is_new: bool) -> LibraryStatus:
                 # Convert file extension list to ts_ignore file, if a .ts_ignore file does not exist
                 self.migrate_sql_to_ts_ignore(library_dir)
 
+            session.execute(
+                text("CREATE INDEX IF NOT EXISTS idx_tags_name_shorthand ON tags (name, shorthand)")
+            )
+            session.execute(
+                text(
+                    "CREATE INDEX IF NOT EXISTS idx_tag_parents_child_id ON tag_parents (child_id)"
+                )
+            )
+            session.execute(
+                text(
+                    "CREATE INDEX IF NOT EXISTS idx_tag_entries_entry_id ON tag_entries (entry_id)"
+                )
+            )
+
             # Update DB_VERSION
             if loaded_db_version < DB_VERSION:
                 self.set_version(DB_VERSION_CURRENT_KEY, DB_VERSION)
@@ -1054,55 +1068,58 @@ def search_library(
 
             return res
 
-    def search_tags(self, name: str | None, limit: int = 100) -> list[set[Tag]]:
+    def search_tags(self, name: str | None, limit: int = 100) -> tuple[list[Tag], list[Tag]]:
         """Return a list of Tag records matching the query."""
+        name = name or ""
+        name = name.lower()
+
+        def sort_key(text: str):
+            priority = text.startswith(name)
+            p_ordering = len(text) if priority else sys.maxsize
+            return (not priority, p_ordering, text)
+
         with Session(self.engine) as session:
-            query = select(Tag).outerjoin(TagAlias).order_by(func.lower(Tag.name))
-            query = query.options(
-                selectinload(Tag.parent_tags),
-                selectinload(Tag.aliases),
-            )
-            if limit > 0:
-                query = query.limit(limit)
+            query = select(Tag.id, Tag.name)
+
+            if limit > 0 and not name:
+                query = query.order_by(Tag.name).limit(limit)
 
             if name:
                 query = query.where(
                     or_(
                         Tag.name.icontains(name),
                         Tag.shorthand.icontains(name),
-                        TagAlias.name.icontains(name),
                     )
                 )
 
-            direct_tags = set(session.scalars(query))
-            ancestor_tag_ids: list[Tag] = []
-            for tag in direct_tags:
-                ancestor_tag_ids.extend(
-                    list(session.scalars(TAG_CHILDREN_QUERY, {"tag_id": tag.id}))
-                )
+            tags = list(session.execute(query))
 
-            ancestor_tags = session.scalars(
-                select(Tag)
-                .where(Tag.id.in_(ancestor_tag_ids))
-                .options(selectinload(Tag.parent_tags), selectinload(Tag.aliases))
-            )
+            if name:
+                query = select(TagAlias.tag_id, TagAlias.name).where(TagAlias.name.icontains(name))
+                tags.extend(session.execute(query))
 
-            res = [
-                direct_tags,
-                {at for at in ancestor_tags if at not in direct_tags},
-            ]
+            tags.sort(key=lambda t: sort_key(t[1]))
+            # Use order from Tag.name or TagAlias.name depending on which comes first for each tag.
+            # Value=0 to avoid unnecessary copying of tag names.
+            tag_ids = list(dict((id, 0) for id, _ in tags).keys())
 
             logger.info(
                 "searching tags",
                 search=name,
                 limit=limit,
                 statement=str(query),
-                results=len(res),
+                results=len(tag_ids),
             )
 
-            session.expunge_all()
+            if limit <= 0:
+                limit = len(tag_ids)
+            tag_ids = tag_ids[:limit]
 
-            return res
+            hierarchy = self.get_tag_hierarchy(tag_ids)
+            direct_tags = [hierarchy.pop(id) for id in tag_ids]
+            ancestor_tags = list(hierarchy.values())
+            ancestor_tags.sort(key=lambda t: sort_key(t.name))
+            return direct_tags, ancestor_tags
 
     def update_entry_path(self, entry_id: int | Entry, path: Path) -> bool:
         """Set the path field of an entry.

src/tagstudio/qt/mixed/tag_search.py

@@ -218,32 +218,13 @@ def update_tags(self, query: str | None = None):
             self.scroll_layout.takeAt(self.scroll_layout.count() - 1).widget().deleteLater()
             self.create_button_in_layout = False
 
-        # Get results for the search query
-        query_lower = "" if not query else query.lower()
         # Only use the tag limit if it's an actual number (aka not "All Tags")
         tag_limit = TagSearchPanel.tag_limit if isinstance(TagSearchPanel.tag_limit, int) else -1
-        tag_results: list[set[Tag]] = self.lib.search_tags(name=query, limit=tag_limit)
-        if self.exclude:
-            tag_results[0] = {t for t in tag_results[0] if t.id not in self.exclude}
-            tag_results[1] = {t for t in tag_results[1] if t.id not in self.exclude}
-
-        # Sort and prioritize the results
-        results_0 = list(tag_results[0])
-        results_0.sort(key=lambda tag: tag.name.lower())
-        results_1 = list(tag_results[1])
-        results_1.sort(key=lambda tag: tag.name.lower())
-        raw_results = list(results_0 + results_1)
-        priority_results: set[Tag] = set()
-        all_results: list[Tag] = []
+        direct_tags, ancestor_tags = self.lib.search_tags(name=query, limit=tag_limit)
 
-        if query and query.strip():
-            for tag in raw_results:
-                if tag.name.lower().startswith(query_lower):
-                    priority_results.add(tag)
+        all_results = [t for t in direct_tags if t.id not in self.exclude]
+        all_results.extend(t for t in ancestor_tags if t.id not in self.exclude)
 
-        all_results = sorted(list(priority_results), key=lambda tag: len(tag.name)) + [
-            r for r in raw_results if r not in priority_results
-        ]
         if tag_limit > 0:
             all_results = all_results[:tag_limit]
 

tests/test_library.py

@@ -131,10 +131,10 @@ def test_library_search(library: Library, entry_full: Entry):
 def test_tag_search(library: Library):
     tag = library.tags[0]
 
-    assert library.search_tags(tag.name.lower())
-    assert library.search_tags(tag.name.upper())
-    assert library.search_tags(tag.name[2:-2])
-    assert library.search_tags(tag.name * 2) == [set(), set()]
+    assert library.search_tags(tag.name.lower())[0]
+    assert library.search_tags(tag.name.upper())[0]
+    assert library.search_tags(tag.name[2:-2])[0]
+    assert library.search_tags(tag.name * 2) == ([], [])
 
 
 def test_get_entry(library: Library, entry_min: Entry):