refactor: key promotion snapshots by name once per promotion

Build the name-keyed snapshots dict once in SnapshotEvaluator.promote instead
of once per promoted view, keep the TableMapping cache across copy(), and pin
the number of replace_tables calls made during promotion.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Rwe8v9iP3iGKVygBfPEZaU
Signed-off-by: mday-io <mdaytn@gmail.com>

Author: claude

sqlmesh/core/renderer.py

@@ -65,6 +65,10 @@ def normalized_keys(self, dialect: DialectType) -> t.Dict[str, str]:
             self._normalized_keys[dialect] = normalized_keys
         return normalized_keys
 
+    def copy(self) -> TableMapping:
+        # dict.copy() would return a plain dict and lose the cache.
+        return TableMapping(self)
+
     def __setitem__(self, key: str, value: str) -> None:
         self._normalized_keys.clear()
         super().__setitem__(key, value)

sqlmesh/core/snapshot/evaluator.py

@@ -312,6 +312,8 @@ def promote(
         self._get_virtual_data_objects(target_snapshots, environment_naming_info)
 
         deployability_index = deployability_index or DeployabilityIndex.all_deployable()
+        # Renderers look snapshots up by model name, not by SnapshotId.
+        snapshots_by_name = {s.name: s for s in (snapshots or {}).values()}
         with self.concurrent_context():
             concurrent_apply_to_snapshots(
                 target_snapshots,
@@ -320,7 +322,7 @@ def promote(
                     start=start,
                     end=end,
                     execution_time=execution_time,
-                    snapshots=snapshots,
+                    snapshots=snapshots_by_name,
                     table_mapping=table_mapping,
                     environment_naming_info=environment_naming_info,
                     deployability_index=deployability_index,  # type: ignore
@@ -1260,7 +1262,7 @@ def _promote_snapshot(
         start: t.Optional[TimeLike] = None,
         end: t.Optional[TimeLike] = None,
         execution_time: t.Optional[TimeLike] = None,
-        snapshots: t.Optional[t.Dict[SnapshotId, Snapshot]] = None,
+        snapshots: t.Optional[t.Dict[str, Snapshot]] = None,
         table_mapping: t.Optional[t.Dict[str, str]] = None,
     ) -> None:
         if not snapshot.is_model:
@@ -1284,8 +1286,6 @@ def _promote_snapshot(
             table_mapping=table_mapping,
             runtime_stage=RuntimeStage.PROMOTING,
         )
-        # Renderers look snapshots up by model name, not by SnapshotId.
-        snapshots_by_name = {s.name: s for s in (snapshots or {}).values()}
 
         with (
             adapter.transaction(),
@@ -1296,15 +1296,13 @@ def _promote_snapshot(
                 view_name=view_name,
                 model=snapshot.model,
                 environment=environment_naming_info.name,
-                snapshots=snapshots_by_name,
+                snapshots=snapshots,
                 snapshot=snapshot,
                 **render_kwargs,
             )
 
             adapter.execute(
-                snapshot.model.render_on_virtual_update(
-                    snapshots=snapshots_by_name, **render_kwargs
-                )
+                snapshot.model.render_on_virtual_update(snapshots=snapshots, **render_kwargs)
             )
 
         if on_complete is not None:

tests/core/test_model.py

@@ -10285,6 +10285,9 @@ def test_table_mapping_normalized_keys(dialect: str):
     # Normalization happens once per dialect.
     assert table_mapping.normalized_keys(dialect) is normalized
 
+    assert isinstance(table_mapping.copy(), TableMapping)
+    assert table_mapping.copy() == table_mapping
+
     # Every mutation invalidates the cache.
     table_mapping["db.b"] = "view_b"
     assert "db.b" in table_mapping.normalized_keys("duckdb")

tests/core/test_snapshot_evaluator.py

@@ -5762,6 +5762,7 @@ def test_promote_resolves_this_model_with_single_mapping_entry(
     )
 
     assert adapter_mock.create_view.call_count == 20
-    assert spy.call_count >= 20
+    # One call per view, to resolve `this_model`.
+    assert spy.call_count == 20
     for call in spy.call_args_list:
         assert len(call.args[1]) == 1