WIP
diff --git a/pyproject.toml b/pyproject.toml
index b8c5ebb..f513b9f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -148,6 +148,7 @@
impala = ["impyla>0.16.2, <0.17"]
kusto = ["sqlalchemy-kusto>=3.0.0, <4"]
kylin = ["kylinpy>=2.8.1, <2.9"]
+metricflow = ["shillelagh[dbtmetricflowapi]>=1.4.2, <2"]
motherduck = ["duckdb==0.10.2", "duckdb-engine>=0.12.1, <0.13"]
mssql = ["pymssql>=2.2.8, <3"]
mysql = ["mysqlclient>=2.1.0, <3"]
diff --git a/superset/db_engine_specs/metricflow.py b/superset/db_engine_specs/metricflow.py
new file mode 100644
index 0000000..e1c9c21
--- /dev/null
+++ b/superset/db_engine_specs/metricflow.py
@@ -0,0 +1,189 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+"""
+An interface to dbt's semantic layer, Metric Flow.
+"""
+
+from __future__ import annotations
+
+from datetime import timedelta
+from typing import Any, TYPE_CHECKING
+
+from shillelagh.backends.apsw.dialects.base import get_adapter_for_table_name
+from shillelagh.backends.apsw.dialects.metricflow import TABLE_NAME
+from sqlalchemy import event
+from sqlalchemy.engine import Engine
+from sqlalchemy.pool import _ConnectionRecord
+from sqlalchemy.pool.base import _ConnectionFairy
+
+from superset.connectors.sqla.models import SqlaTable
+from superset.constants import TimeGrain
+from superset.db_engine_specs.base import MetricType, ValidColumnsType
+from superset.db_engine_specs.shillelagh import ShillelaghEngineSpec
+from superset.extensions import cache_manager
+from superset.utils.cache import memoized_func
+
+if TYPE_CHECKING:
+ from shillelagh.backends.apsw.dialects.metricflow import TableMetricFlowAPI
+ from shillelagh.fields import Field
+ from sqlalchemy.engine.reflection import Inspector
+
+ from superset.models.core import Database
+ from superset.sql.parse import Table
+ from superset.superset_typing import ResultSetColumnType
+
+
+@event.listens_for(Engine, "connect")
+def receive_connect(
+ dbapi_connection: _ConnectionFairy,
+ connection_record: _ConnectionRecord,
+) -> None:
+ """
+ Called when a new DB connection is created.
+
+ This hook adds a cache to the `_build_column_from_dimension` method of the Metric
+ Flow adapter, since it's called frequently and can be expensive.
+ """
+ engine = connection_record.info.get("engine")
+ if (
+ not engine
+ or not engine.name == "metricflow"
+ or getattr(engine.dialect, "_patched", False)
+ ):
+ return
+
+ original_method = engine.dialect._build_column_from_dimension
+
+ @memoized_func(
+ key="metricflow:dimension:{name}",
+ cache=cache_manager.data_cache,
+ )
+ def cached_build_column_from_dimension(
+ self: TableMetricFlowAPI,
+ name: str,
+ *args: Any,
+ **kwargs: Any,
+ ) -> Field:
+ return original_method(
+ self,
+ name,
+ cache_timeout=int(timedelta(days=1).total_seconds()),
+ )
+
+ engine.dialect._build_column_from_dimension = cached_build_column_from_dimension
+ engine.dialect._patched = True
+
+
+SELECT_STAR_MESSAGE = (
+ 'The dbt semantic layer does not support data preview, since the "metrics" table '
+ "is a virtual table that is not materialized. An administrator should configure "
+ 'the database in Apache Superset so that the "Disable SQL Lab data preview '
+ 'queries" option under "Advanced" → "SQL Lab" is enabled.'
+)
+
+
+class DbtMetricFlowEngineSpec(ShillelaghEngineSpec):
+ """
+ Engine for the the dbt semantic layer.
+ """
+
+ engine = "metricflow"
+ engine_name = "dbt Metric Flow"
+ sqlalchemy_uri_placeholder = (
+ "metricflow://[ab123.us1.dbt.com]/<environment_id>"
+ "?service_token=<service_token>"
+ )
+
+ supports_dynamic_columns = True
+
+ _time_grain_expressions = {
+ TimeGrain.DAY: "{col}__day",
+ TimeGrain.WEEK: "{col}__week",
+ TimeGrain.MONTH: "{col}__month",
+ TimeGrain.QUARTER: "{col}__quarter",
+ TimeGrain.YEAR: "{col}__year",
+ }
+
+ @classmethod
+ def select_star(cls, *args: Any, **kwargs: Any) -> str:
+ """
+ Return a ``SELECT *`` query.
+ """
+ message = SELECT_STAR_MESSAGE.replace("'", "''")
+ return f"SELECT '{message}' AS warning"
+
+ @classmethod
+ def get_columns(
+ cls,
+ inspector: Inspector,
+ table: Table,
+ options: dict[str, Any] | None = None,
+ ) -> list[ResultSetColumnType]:
+ columns: list[ResultSetColumnType] = []
+
+ for column in inspector.get_columns(table.table, table.schema):
+ # ignore metrics
+ if "computed" in column:
+ continue
+
+ column["column_name"] = column["name"]
+ columns.append(column)
+
+ return columns
+
+ @classmethod
+ def get_metrics(
+ cls,
+ database: Database,
+ inspector: Inspector,
+ table: Table,
+ ) -> list[MetricType]:
+ """
+ Get all metrics.
+ """
+ return [
+ {
+ "metric_name": column["name"],
+ "expression": column["computed"]["sqltext"],
+ "description": column["comment"],
+ }
+ for column in inspector.get_columns(table.table, table.schema)
+ if "computed" in column
+ ]
+
+ @classmethod
+ def get_valid_metrics_and_dimensions(
+ cls,
+ database: Database,
+ table: SqlaTable,
+ dimensions: set[str],
+ metrics: set[str],
+ ) -> ValidColumnsType:
+ """
+ Get valid metrics and dimensions.
+
+ Given a datasource, and sets of selected metrics and dimensions, return the
+ sets of valid metrics and dimensions that can further be selected.
+ """
+ with database.get_sqla_engine() as engine:
+ connection = engine.connect()
+ adapter = get_adapter_for_table_name(connection, TABLE_NAME)
+
+ return {
+ "metrics": adapter._get_metrics_for_dimensions(dimensions),
+ "dimensions": adapter._get_dimensions_for_metrics(metrics),
+ }
