server/tags: improve tag export performance

2000 ms --> 250 ms (including overhead of unknown size).
Not bad if you ask me.

server/szurubooru/func/tags.py

@@ -55,34 +55,51 @@ def serialize_tag(tag, options=None):
         options)
 
 def export_to_json():
+    tags = {}
+    categories = {}
+
+    for result in db.session.query(
+            db.TagCategory.tag_category_id,
+            db.TagCategory.name,
+            db.TagCategory.color).all():
+        categories[result[0]] = {
+            'name': result[1],
+            'color': result[2],
+        }
+
+    for result in db.session.query(db.TagName.tag_id, db.TagName.name).all():
+        if not result[0] in tags:
+            tags[result[0]] = {'names': []}
+        tags[result[0]]['names'].append(result[1])
+
+    for result in db.session \
+            .query(db.TagSuggestion.parent_id, db.TagName.name) \
+            .join(db.TagName, db.TagName.tag_id == db.TagSuggestion.child_id) \
+            .all():
+        if not 'suggestions' in tags[result[0]]:
+            tags[result[0]]['suggestions'] = []
+        tags[result[0]]['suggestions'].append(result[1])
+
+    for result in db.session \
+            .query(db.TagImplication.parent_id, db.TagName.name) \
+            .join(db.TagName, db.TagName.tag_id == db.TagImplication.child_id) \
+            .all():
+        if not 'implications' in tags[result[0]]:
+            tags[result[0]]['implications'] = []
+        tags[result[0]]['implications'].append(result[1])
+
+    for result in db.session.query(
+            db.Tag.tag_id,
+            db.Tag.category_id,
+            db.Tag.post_count).all():
+        tags[result[0]]['category'] = categories[result[1]]['name']
+        tags[result[0]]['usages'] = result[2]
+
     output = {
-        'tags': [],
+        'categories': list(categories.values()),
-        'categories': [],
+        'tags': list(tags.values()),
     }
-    all_tags = db.session \
+
-        .query(db.Tag) \
-        .options(
-            sqlalchemy.orm.joinedload('suggestions'),
-            sqlalchemy.orm.joinedload('implications')) \
-        .all()
-    for tag in all_tags:
-        item = {
-            'names': [tag_name.name for tag_name in tag.names],
-            'usages': tag.post_count,
-            'category': tag.category.name,
-        }
-        if len(tag.suggestions):
-            item['suggestions'] = \
-                [rel.names[0].name for rel in tag.suggestions]
-        if len(tag.implications):
-            item['implications'] = \
-                [rel.names[0].name for rel in tag.implications]
-        output['tags'].append(item)
-    for category in tag_categories.get_all_categories():
-        output['categories'].append({
-            'name': category.name,
-            'color': category.color,
-        })
     export_path = os.path.join(config.config['data_dir'], 'tags.json')
     with open(export_path, 'w') as handle:
         handle.write(json.dumps(output, separators=(',', ':')))

server/szurubooru/tests/api/test_tag_export.py

@@ -8,6 +8,7 @@ def test_export(
         tmpdir,
         query_counter,
         config_injector,
+        post_factory,
         tag_factory,
         tag_category_factory):
     config_injector({
@@ -22,10 +23,12 @@ def test_export(
     imp1 = tag_factory(names=['imp1'], category=cat1)
     imp2 = tag_factory(names=['imp2'], category=cat1)
     tag = tag_factory(names=['alias1', 'alias2'], category=cat2)
-    tag.post_count = 1
     db.session.add_all([tag, sug1, sug2, imp1, imp2, cat1, cat2])
+    post = post_factory()
+    post.tags = [tag]
     db.session.flush()
     db.session.add_all([
+        post,
         db.TagSuggestion(tag.tag_id, sug1.tag_id),
         db.TagSuggestion(tag.tag_id, sug2.tag_id),
         db.TagImplication(tag.tag_id, imp1.tag_id),
@@ -35,7 +38,7 @@ def test_export(
 
     with query_counter:
         tags.export_to_json()
-        assert len(query_counter.statements) == 2
+        assert len(query_counter.statements) == 5
 
     export_path = os.path.join(config.config['data_dir'], 'tags.json')
     assert os.path.exists(export_path)