make get_addressdata calls cachable

VALUEs() is not a cachable construct in SQLAlchemy, so use arrays
instead. Also add a special case for single results, the usual result
for reverse queries.

nominatim/api/results.py

@@ -11,14 +11,14 @@ Data classes are part of the public API while the functions are for
 internal use only. That's why they are implemented as free-standing functions
 instead of member functions.
 """
-from typing import Optional, Tuple, Dict, Sequence, TypeVar, Type, List, Any
+from typing import Optional, Tuple, Dict, Sequence, TypeVar, Type, List, Any, Union
 import enum
 import dataclasses
 import datetime as dt
 
 import sqlalchemy as sa
 
-from nominatim.typing import SaSelect, SaRow
+from nominatim.typing import SaSelect, SaRow, SaColumn
 from nominatim.api.types import Point, Bbox, LookupDetails
 from nominatim.api.connection import SearchConnection
 from nominatim.api.logging import log
@@ -418,46 +418,74 @@ def _result_row_to_address_row(row: SaRow) -> AddressLine:
                        distance=row.distance)
 
 
+def _get_housenumber_details(results: List[BaseResultT]) -> Tuple[List[int], List[int]]:
+    places = []
+    hnrs = []
+    for result in results:
+        if result.place_id:
+            housenumber = -1
+            if result.source_table in (SourceTable.TIGER, SourceTable.OSMLINE):
+                if result.housenumber is not None:
+                    housenumber = int(result.housenumber)
+                elif result.extratags is not None and 'startnumber' in result.extratags:
+                    # details requests do not come with a specific house number
+                    housenumber = int(result.extratags['startnumber'])
+            places.append(result.place_id)
+            hnrs.append(housenumber)
+
+    return places, hnrs
+
+
 async def complete_address_details(conn: SearchConnection, results: List[BaseResultT]) -> None:
     """ Retrieve information about places that make up the address of the result.
     """
-    def get_hnr(result: BaseResult) -> Tuple[int, int]:
-        housenumber = -1
-        if result.source_table in (SourceTable.TIGER, SourceTable.OSMLINE):
-            if result.housenumber is not None:
-                housenumber = int(result.housenumber)
-            elif result.extratags is not None and 'startnumber' in result.extratags:
-                # details requests do not come with a specific house number
-                housenumber = int(result.extratags['startnumber'])
-        assert result.place_id
-        return result.place_id, housenumber
+    places, hnrs = _get_housenumber_details(results)
 
-    data: List[Tuple[Any, ...]] = [get_hnr(r) for r in results if r.place_id]
-
-    if not data:
+    if not places:
         return
 
-    values = sa.values(sa.column('place_id', type_=sa.Integer),
-                       sa.column('housenumber', type_=sa.Integer),
-                       name='places',
-                       literal_binds=True).data(data)
+    def _get_addressdata(place_id: Union[int, SaColumn], hnr: Union[int, SaColumn]) -> Any:
+        return sa.func.get_addressdata(place_id, hnr)\
+                    .table_valued( # type: ignore[no-untyped-call]
+                        sa.column('place_id', type_=sa.Integer),
+                        'osm_type',
+                        sa.column('osm_id', type_=sa.BigInteger),
+                        sa.column('name', type_=conn.t.types.Composite),
+                        'class', 'type', 'place_type',
+                        sa.column('admin_level', type_=sa.Integer),
+                        sa.column('fromarea', type_=sa.Boolean),
+                        sa.column('isaddress', type_=sa.Boolean),
+                        sa.column('rank_address', type_=sa.SmallInteger),
+                        sa.column('distance', type_=sa.Float),
+                        joins_implicitly=True)
 
-    sfn = sa.func.get_addressdata(values.c.place_id, values.c.housenumber)\
-                .table_valued( # type: ignore[no-untyped-call]
-                    sa.column('place_id', type_=sa.Integer),
-                    'osm_type',
-                    sa.column('osm_id', type_=sa.BigInteger),
-                    sa.column('name', type_=conn.t.types.Composite),
-                    'class', 'type', 'place_type',
-                    sa.column('admin_level', type_=sa.Integer),
-                    sa.column('fromarea', type_=sa.Boolean),
-                    sa.column('isaddress', type_=sa.Boolean),
-                    sa.column('rank_address', type_=sa.SmallInteger),
-                    sa.column('distance', type_=sa.Float),
-                    joins_implicitly=True)
 
-    sql = sa.select(values.c.place_id.label('result_place_id'), sfn)\
-            .order_by(values.c.place_id,
+    if len(places) == 1:
+        # Optimized case for exactly one result (reverse)
+        sql = sa.select(_get_addressdata(places[0], hnrs[0]))\
+                .order_by(sa.column('rank_address').desc(),
+                          sa.column('isaddress').desc())
+
+        alines = AddressLines()
+        for row in await conn.execute(sql):
+            alines.append(_result_row_to_address_row(row))
+
+        for result in results:
+            if result.place_id == places[0]:
+                result.address_rows = alines
+                return
+
+
+    darray = sa.func.unnest(conn.t.types.to_array(places), conn.t.types.to_array(hnrs))\
+                    .table_valued( # type: ignore[no-untyped-call]
+                       sa.column('place_id', type_= sa.Integer),
+                       sa.column('housenumber', type_= sa.Integer)
+                    ).render_derived()
+
+    sfn = _get_addressdata(darray.c.place_id, darray.c.housenumber)
+
+    sql = sa.select(darray.c.place_id.label('result_place_id'), sfn)\
+            .order_by(darray.c.place_id,
                       sa.column('rank_address').desc(),
                       sa.column('isaddress').desc())