feat: instead of hardcoding child tag ids into main query, include subquery

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

@@ -1,9 +1,13 @@
 from typing import TYPE_CHECKING
 
 import structlog
-from sqlalchemy import and_, distinct, func, or_, select, text
+from sqlalchemy import and_, column, distinct, func, or_, select, text, union_all
 from sqlalchemy.orm import Session
-from sqlalchemy.sql.expression import BinaryExpression, ColumnExpressionArgument
+from sqlalchemy.sql.expression import (
+    BinaryExpression,
+    ColumnExpressionArgument,
+    CompoundSelect,
+)
 from src.core.media_types import FILETYPE_EQUIVALENTS, MediaCategories
 from src.core.query_lang import BaseVisitor
 from src.core.query_lang.ast import AST, ANDList, Constraint, ConstraintType, Not, ORList, Property
@@ -28,7 +32,7 @@ WITH RECURSIVE Subtags AS (
 	FROM tag_subtags ts
     INNER JOIN Subtags s ON ts.child_id = s.child_id
 )
-SELECT * FROM Subtags;
+SELECT child_id FROM Subtags
 """)  # noqa: E501
 
 
@@ -59,7 +63,10 @@ class SQLBoolExpressionBuilder(BaseVisitor[ColumnExpressionArgument]):
                         tag_ids.append(int(term.value))
                         continue
                     case ConstraintType.Tag:
-                        if len(ids := self.__get_tag_ids(term.value)) == 1:
+                        if (
+                            isinstance((ids := self.__get_tag_ids(term.value)), list)
+                            and len(ids) == 1
+                        ):
                             tag_ids.append(ids[0])
                             continue
 
@@ -113,7 +120,9 @@ class SQLBoolExpressionBuilder(BaseVisitor[ColumnExpressionArgument]):
     def visit_not(self, node: Not) -> ColumnExpressionArgument:
         return ~self.__entry_satisfies_ast(node.child)
 
-    def __get_tag_ids(self, tag_name: str, include_children: bool = True) -> list[int]:
+    def __get_tag_ids(
+        self, tag_name: str, include_children: bool = True
+    ) -> list[int] | CompoundSelect:
         """Given a tag name find the ids of all tags that this name could refer to."""
         with Session(self.lib.engine) as session:
             tag_ids = list(
@@ -131,10 +140,13 @@ class SQLBoolExpressionBuilder(BaseVisitor[ColumnExpressionArgument]):
                 )
             if not include_children:
                 return tag_ids
-            outp = []
-            for tag_id in tag_ids:
-                outp.extend(list(session.scalars(CHILDREN_QUERY, {"tag_id": tag_id})))
-            return outp
+            queries = [
+                CHILDREN_QUERY.bindparams(tag_id=id).columns(column("child_id")) for id in tag_ids
+            ]
+            outp = union_all(*queries)
+            # if only one tag is found return that a list with that tag instead,
+            # in order to make use of the optimisations in __entry_has_all_tags
+            return t if len(t := list(session.scalars(outp))) == 1 else outp
 
     def __entry_has_all_tags(self, tag_ids: list[int]) -> BinaryExpression[bool]:
         """Returns Binary Expression that is true if the Entry has all provided tag ids."""