superset/db_engine_specs/clickhouse.py

# 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.
import logging
from datetime import datetime
from typing import Dict, List, Optional, Type, TYPE_CHECKING

from urllib3.exceptions import NewConnectionError

from superset.db_engine_specs.base import BaseEngineSpec
from superset.db_engine_specs.exceptions import SupersetDBAPIDatabaseError
from superset.extensions import cache_manager
from superset.utils import core as utils

if TYPE_CHECKING:
    # prevent circular imports
    from superset.models.core import Database

logger = logging.getLogger(__name__)


class ClickHouseEngineSpec(BaseEngineSpec):  # pylint: disable=abstract-method
    """Dialect for ClickHouse analytical DB."""

    engine = "clickhouse"
    engine_name = "ClickHouse"

    time_secondary_columns = True
    time_groupby_inline = True

    _time_grain_expressions = {
        None: "{col}",
        "PT1M": "toStartOfMinute(toDateTime({col}))",
        "PT5M": "toDateTime(intDiv(toUInt32(toDateTime({col})), 300)*300)",
        "PT10M": "toDateTime(intDiv(toUInt32(toDateTime({col})), 600)*600)",
        "PT15M": "toDateTime(intDiv(toUInt32(toDateTime({col})), 900)*900)",
        "PT0.5H": "toDateTime(intDiv(toUInt32(toDateTime({col})), 1800)*1800)",
        "PT1H": "toStartOfHour(toDateTime({col}))",
        "P1D": "toStartOfDay(toDateTime({col}))",
        "P1W": "toMonday(toDateTime({col}))",
        "P1M": "toStartOfMonth(toDateTime({col}))",
        "P0.25Y": "toStartOfQuarter(toDateTime({col}))",
        "P1Y": "toStartOfYear(toDateTime({col}))",
    }

    _show_functions_column = "name"

    @classmethod
    def get_dbapi_exception_mapping(cls) -> Dict[Type[Exception], Type[Exception]]:
        return {NewConnectionError: SupersetDBAPIDatabaseError}

    @classmethod
    def get_dbapi_mapped_exception(cls, exception: Exception) -> Exception:
        new_exception = cls.get_dbapi_exception_mapping().get(type(exception))
        if new_exception == SupersetDBAPIDatabaseError:
            return SupersetDBAPIDatabaseError("Connection failed")
        if not new_exception:
            return exception
        return new_exception(str(exception))

    @classmethod
    def convert_dttm(cls, target_type: str, dttm: datetime) -> Optional[str]:
        tt = target_type.upper()
        if tt == utils.TemporalType.DATE:
            return f"toDate('{dttm.date().isoformat()}')"
        if tt == utils.TemporalType.DATETIME:
            return f"""toDateTime('{dttm.isoformat(sep=" ", timespec="seconds")}')"""
        return None

    @classmethod
    @cache_manager.cache.memoize()
    def get_function_names(cls, database: "Database") -> List[str]:
        """
        Get a list of function names that are able to be called on the database.
        Used for SQL Lab autocomplete.

        :param database: The database to get functions for
        :return: A list of function names usable in the database
        """
        system_functions_sql = "SELECT name FROM system.functions"
        try:
            df = database.get_df(system_functions_sql)
            if cls._show_functions_column in df:
                return df[cls._show_functions_column].tolist()
            columns = df.columns.values.tolist()
            logger.error(
                "Payload from `%s` has the incorrect format. "
                "Expected column `%s`, found: %s.",
                system_functions_sql,
                cls._show_functions_column,
                ", ".join(columns),
                exc_info=True,
            )
            # if the results have a single column, use that
            if len(columns) == 1:
                return df[columns[0]].tolist()
        except Exception as ex:  # pylint: disable=broad-except
            logger.error(
                "Query `%s` fire error %s. ",
                system_functions_sql,
                str(ex),
                exc_info=True,
            )
            return []

        # otherwise, return no function names to prevent errors
        return []