superset2/superset/db_engine_specs/base.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.
# pylint: disable=too-many-lines

from __future__ import annotations

import json
import logging
import re
from datetime import datetime
from typing import (
    Any,
    Callable,
    ContextManager,
    Dict,
    List,
    Match,
    NamedTuple,
    Optional,
    Pattern,
    Set,
    Tuple,
    Type,
    TYPE_CHECKING,
    Union,
)

import pandas as pd
import sqlparse
from apispec import APISpec
from apispec.ext.marshmallow import MarshmallowPlugin
from flask import current_app
from flask_appbuilder.security.sqla.models import User
from flask_babel import gettext as __, lazy_gettext as _
from marshmallow import fields, Schema
from marshmallow.validate import Range
from sqlalchemy import column, select, types
from sqlalchemy.engine.base import Engine
from sqlalchemy.engine.interfaces import Compiled, Dialect
from sqlalchemy.engine.reflection import Inspector
from sqlalchemy.engine.url import URL
from sqlalchemy.ext.compiler import compiles
from sqlalchemy.orm import Session
from sqlalchemy.sql import quoted_name, text
from sqlalchemy.sql.expression import ColumnClause, Select, TextAsFrom, TextClause
from sqlalchemy.types import TypeEngine
from sqlparse.tokens import CTE
from typing_extensions import TypedDict

from superset import security_manager, sql_parse
from superset.databases.utils import make_url_safe
from superset.errors import ErrorLevel, SupersetError, SupersetErrorType
from superset.sql_parse import ParsedQuery, Table
from superset.superset_typing import ResultSetColumnType
from superset.utils import core as utils
from superset.utils.core import ColumnSpec, GenericDataType, get_username
from superset.utils.hashing import md5_sha_from_str
from superset.utils.network import is_hostname_valid, is_port_open

if TYPE_CHECKING:
    # prevent circular imports
    from superset.connectors.sqla.models import TableColumn
    from superset.models.core import Database
    from superset.models.sql_lab import Query

ColumnTypeMapping = Tuple[
    Pattern[str],
    Union[TypeEngine, Callable[[Match[str]], TypeEngine]],
    GenericDataType,
]

logger = logging.getLogger()


CTE_ALIAS = "__cte"


class TimeGrain(NamedTuple):
    name: str  # TODO: redundant field, remove
    label: str
    function: str
    duration: Optional[str]


builtin_time_grains: Dict[Optional[str], str] = {
    "PT1S": __("Second"),
    "PT5S": __("5 second"),
    "PT30S": __("30 second"),
    "PT1M": __("Minute"),
    "PT5M": __("5 minute"),
    "PT10M": __("10 minute"),
    "PT15M": __("15 minute"),
    "PT30M": __("30 minute"),
    "PT1H": __("Hour"),
    "PT6H": __("6 hour"),
    "P1D": __("Day"),
    "P1W": __("Week"),
    "P1M": __("Month"),
    "P3M": __("Quarter"),
    "P1Y": __("Year"),
    "1969-12-28T00:00:00Z/P1W": __("Week starting Sunday"),
    "1969-12-29T00:00:00Z/P1W": __("Week starting Monday"),
    "P1W/1970-01-03T00:00:00Z": __("Week ending Saturday"),
    "P1W/1970-01-04T00:00:00Z": __("Week_ending Sunday"),
}


class TimestampExpression(
    ColumnClause
):  # pylint: disable=abstract-method, too-many-ancestors
    def __init__(self, expr: str, col: ColumnClause, **kwargs: Any) -> None:
        """Sqlalchemy class that can be can be used to render native column elements
        respeting engine-specific quoting rules as part of a string-based expression.

        :param expr: Sql expression with '{col}' denoting the locations where the col
        object will be rendered.
        :param col: the target column
        """
        super().__init__(expr, **kwargs)
        self.col = col

    @property
    def _constructor(self) -> ColumnClause:
        # Needed to ensure that the column label is rendered correctly when
        # proxied to the outer query.
        # See https://github.com/sqlalchemy/sqlalchemy/issues/4730
        return ColumnClause


@compiles(TimestampExpression)
def compile_timegrain_expression(
    element: TimestampExpression, compiler: Compiled, **kwargs: Any
) -> str:
    return element.name.replace("{col}", compiler.process(element.col, **kwargs))


class LimitMethod:  # pylint: disable=too-few-public-methods
    """Enum the ways that limits can be applied"""

    FETCH_MANY = "fetch_many"
    WRAP_SQL = "wrap_sql"
    FORCE_LIMIT = "force_limit"


class MetricType(TypedDict, total=False):
    """
    Type for metrics return by `get_metrics`.
    """

    metric_name: str
    expression: str
    verbose_name: Optional[str]
    metric_type: Optional[str]
    description: Optional[str]
    d3format: Optional[str]
    warning_text: Optional[str]
    extra: Optional[str]


class BaseEngineSpec:  # pylint: disable=too-many-public-methods
    """Abstract class for database engine specific configurations

    Attributes:
        allows_alias_to_source_column: Whether the engine is able to pick the
                                       source column for aggregation clauses
                                       used in ORDER BY when a column in SELECT
                                       has an alias that is the same as a source
                                       column.
        allows_hidden_orderby_agg:     Whether the engine allows ORDER BY to
                                       directly use aggregation clauses, without
                                       having to add the same aggregation in SELECT.
    """

    engine_name: Optional[str] = None  # for user messages, overridden in child classes

    # These attributes map the DB engine spec to one or more SQLAlchemy dialects/drivers;
    # see the ``supports_url`` and ``supports_backend`` methods below.
    engine = "base"  # str as defined in sqlalchemy.engine.engine
    engine_aliases: Set[str] = set()
    drivers: Dict[str, str] = {}
    default_driver: Optional[str] = None
    disable_ssh_tunneling = False

    _date_trunc_functions: Dict[str, str] = {}
    _time_grain_expressions: Dict[Optional[str], str] = {}
    column_type_mappings: Tuple[ColumnTypeMapping, ...] = (
        (
            re.compile(r"^string", re.IGNORECASE),
            types.String(),
            GenericDataType.STRING,
        ),
        (
            re.compile(r"^n((var)?char|text)", re.IGNORECASE),
            types.UnicodeText(),
            GenericDataType.STRING,
        ),
        (
            re.compile(r"^(var)?char", re.IGNORECASE),
            types.String(),
            GenericDataType.STRING,
        ),
        (
            re.compile(r"^(tiny|medium|long)?text", re.IGNORECASE),
            types.String(),
            GenericDataType.STRING,
        ),
        (
            re.compile(r"^smallint", re.IGNORECASE),
            types.SmallInteger(),
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^int(eger)?", re.IGNORECASE),
            types.Integer(),
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^bigint", re.IGNORECASE),
            types.BigInteger(),
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^long", re.IGNORECASE),
            types.Float(),
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^decimal", re.IGNORECASE),
            types.Numeric(),
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^numeric", re.IGNORECASE),
            types.Numeric(),
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^float", re.IGNORECASE),
            types.Float(),
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^double", re.IGNORECASE),
            types.Float(),
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^real", re.IGNORECASE),
            types.REAL,
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^smallserial", re.IGNORECASE),
            types.SmallInteger(),
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^serial", re.IGNORECASE),
            types.Integer(),
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^bigserial", re.IGNORECASE),
            types.BigInteger(),
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^money", re.IGNORECASE),
            types.Numeric(),
            GenericDataType.NUMERIC,
        ),
        (
            re.compile(r"^timestamp", re.IGNORECASE),
            types.TIMESTAMP(),
            GenericDataType.TEMPORAL,
        ),
        (
            re.compile(r"^datetime", re.IGNORECASE),
            types.DateTime(),
            GenericDataType.TEMPORAL,
        ),
        (
            re.compile(r"^date", re.IGNORECASE),
            types.Date(),
            GenericDataType.TEMPORAL,
        ),
        (
            re.compile(r"^time", re.IGNORECASE),
            types.Time(),
            GenericDataType.TEMPORAL,
        ),
        (
            re.compile(r"^interval", re.IGNORECASE),
            types.Interval(),
            GenericDataType.TEMPORAL,
        ),
        (
            re.compile(r"^bool(ean)?", re.IGNORECASE),
            types.Boolean(),
            GenericDataType.BOOLEAN,
        ),
    )

    # Does database support join-free timeslot grouping
    time_groupby_inline = False
    limit_method = LimitMethod.FORCE_LIMIT
    time_secondary_columns = False
    allows_joins = True
    allows_subqueries = True
    allows_alias_in_select = True
    allows_alias_in_orderby = True
    allows_sql_comments = True
    allows_escaped_colons = True

    # Whether ORDER BY clause can use aliases created in SELECT
    # that are the same as a source column
    allows_alias_to_source_column = True

    # Whether ORDER BY clause must appear in SELECT
    # if TRUE, then it doesn't have to.
    allows_hidden_ordeby_agg = True

    # Whether ORDER BY clause can use sql caculated expression
    # if True, use alias of select column for `order by`
    # the True is safely for most database
    # But for backward compatibility, False by default
    allows_hidden_cc_in_orderby = False

    # Whether allow CTE as subquery or regular CTE
    # If True, then it will allow  in subquery ,
    # if False it will allow as regular CTE
    allows_cte_in_subquery = True
    # Whether allow LIMIT clause in the SQL
    # If True, then the database engine is allowed for LIMIT clause
    # If False, then the database engine is allowed for TOP clause
    allow_limit_clause = True
    # This set will give keywords for select statements
    # to consider for the engines with TOP SQL parsing
    select_keywords: Set[str] = {"SELECT"}
    # This set will give the keywords for data limit statements
    # to consider for the engines with TOP SQL parsing
    top_keywords: Set[str] = {"TOP"}

    force_column_alias_quotes = False
    arraysize = 0
    max_column_name_length = 0
    try_remove_schema_from_table_name = True  # pylint: disable=invalid-name
    run_multiple_statements_as_one = False
    custom_errors: Dict[
        Pattern[str], Tuple[str, SupersetErrorType, Dict[str, Any]]
    ] = {}

    # Whether the engine supports file uploads
    # if True, database will be listed as option in the upload file form
    supports_file_upload = True

    @classmethod
    def supports_url(cls, url: URL) -> bool:
        """
        Returns true if the DB engine spec supports a given SQLAlchemy URL.

        As an example, if a given DB engine spec has:

            class PostgresDBEngineSpec:
                engine = "postgresql"
                engine_aliases = "postgres"
                drivers = {
                    "psycopg2": "The default Postgres driver",
                    "asyncpg": "An asynchronous Postgres driver",
                }

        It would be used for all the following SQLAlchemy URIs:

            - postgres://user:password@host/db
            - postgresql://user:password@host/db
            - postgres+asyncpg://user:password@host/db
            - postgres+psycopg2://user:password@host/db
            - postgresql+asyncpg://user:password@host/db
            - postgresql+psycopg2://user:password@host/db

        Note that SQLAlchemy has a default driver even if one is not specified:

            >>> from sqlalchemy.engine.url import make_url
            >>> make_url('postgres://').get_driver_name()
            'psycopg2'

        """
        backend = url.get_backend_name()
        driver = url.get_driver_name()
        return cls.supports_backend(backend, driver)

    @classmethod
    def supports_backend(cls, backend: str, driver: Optional[str] = None) -> bool:
        """
        Returns true if the DB engine spec supports a given SQLAlchemy backend/driver.
        """
        # check the backend first
        if backend != cls.engine and backend not in cls.engine_aliases:
            return False

        # originally DB engine specs didn't declare any drivers and the check was made
        # only on the engine; if that's the case, ignore the driver for backwards
        # compatibility
        if not cls.drivers or driver is None:
            return True

        return driver in cls.drivers

    @classmethod
    def get_dbapi_exception_mapping(cls) -> Dict[Type[Exception], Type[Exception]]:
        """
        Each engine can implement and converge its own specific exceptions into
        Superset DBAPI exceptions

        Note: On python 3.9 this method can be changed to a classmethod property
        without the need of implementing a metaclass type

        :return: A map of driver specific exception to superset custom exceptions
        """
        return {}

    @classmethod
    def parse_error_exception(cls, exception: Exception) -> Exception:
        """
        Each engine can implement and converge its own specific parser method

        :return: An Exception with a parsed string off the original exception
        """
        return exception

    @classmethod
    def get_dbapi_mapped_exception(cls, exception: Exception) -> Exception:
        """
        Get a superset custom DBAPI exception from the driver specific exception.

        Override if the engine needs to perform extra changes to the exception, for
        example change the exception message or implement custom more complex logic

        :param exception: The driver specific exception
        :return: Superset custom DBAPI exception
        """
        new_exception = cls.get_dbapi_exception_mapping().get(type(exception))
        if not new_exception:
            return cls.parse_error_exception(exception)
        return new_exception(str(exception))

    @classmethod
    def get_allow_cost_estimate(  # pylint: disable=unused-argument
        cls,
        extra: Dict[str, Any],
    ) -> bool:
        return False

    @classmethod
    def get_text_clause(cls, clause: str) -> TextClause:
        """
        SQLAlchemy wrapper to ensure text clauses are escaped properly

        :param clause: string clause with potentially unescaped characters
        :return: text clause with escaped characters
        """
        if cls.allows_escaped_colons:
            clause = clause.replace(":", "\\:")
        return text(clause)

    @classmethod
    def get_engine(
        cls,
        database: Database,
        schema: Optional[str] = None,
        source: Optional[utils.QuerySource] = None,
    ) -> ContextManager[Engine]:
        """
        Return an engine context manager.

            >>> with DBEngineSpec.get_engine(database, schema, source) as engine:
            ...     connection = engine.connect()
            ...     connection.execute(sql)

        """
        return database.get_sqla_engine_with_context(schema=schema, source=source)

    @classmethod
    def get_timestamp_expr(
        cls,
        col: ColumnClause,
        pdf: Optional[str],
        time_grain: Optional[str],
    ) -> TimestampExpression:
        """
        Construct a TimestampExpression to be used in a SQLAlchemy query.

        :param col: Target column for the TimestampExpression
        :param pdf: date format (seconds or milliseconds)
        :param time_grain: time grain, e.g. P1Y for 1 year
        :return: TimestampExpression object
        """
        if time_grain:
            type_ = str(getattr(col, "type", ""))
            time_expr = cls.get_time_grain_expressions().get(time_grain)
            if not time_expr:
                raise NotImplementedError(
                    f"No grain spec for {time_grain} for database {cls.engine}"
                )
            if type_ and "{func}" in time_expr:
                date_trunc_function = cls._date_trunc_functions.get(type_)
                if date_trunc_function:
                    time_expr = time_expr.replace("{func}", date_trunc_function)
            if type_ and "{type}" in time_expr:
                date_trunc_function = cls._date_trunc_functions.get(type_)
                if date_trunc_function:
                    time_expr = time_expr.replace("{type}", type_)
        else:
            time_expr = "{col}"

        # if epoch, translate to DATE using db specific conf
        if pdf == "epoch_s":
            time_expr = time_expr.replace("{col}", cls.epoch_to_dttm())
        elif pdf == "epoch_ms":
            time_expr = time_expr.replace("{col}", cls.epoch_ms_to_dttm())

        return TimestampExpression(time_expr, col, type_=col.type)

    @classmethod
    def get_time_grains(cls) -> Tuple[TimeGrain, ...]:
        """
        Generate a tuple of supported time grains.

        :return: All time grains supported by the engine
        """

        ret_list = []
        time_grains = builtin_time_grains.copy()
        time_grains.update(current_app.config["TIME_GRAIN_ADDONS"])
        for duration, func in cls.get_time_grain_expressions().items():
            if duration in time_grains:
                name = time_grains[duration]
                ret_list.append(TimeGrain(name, _(name), func, duration))
        return tuple(ret_list)

    @classmethod
    def _sort_time_grains(
        cls, val: Tuple[Optional[str], str], index: int
    ) -> Union[float, int, str]:
        """
        Return an ordered time-based value of a portion of a time grain
        for sorting
        Values are expected to be either None or start with P or PT
        Have a numerical value in the middle and end with
        a value for the time interval
        It can also start or end with epoch start time denoting a range
        i.e, week beginning or ending with a day
        """
        pos = {
            "FIRST": 0,
            "SECOND": 1,
            "THIRD": 2,
            "LAST": 3,
        }

        if val[0] is None:
            return pos["FIRST"]

        prog = re.compile(r"(.*\/)?(P|PT)([0-9\.]+)(S|M|H|D|W|M|Y)(\/.*)?")
        result = prog.match(val[0])

        # for any time grains that don't match the format, put them at the end
        if result is None:
            return pos["LAST"]

        second_minute_hour = ["S", "M", "H"]
        day_week_month_year = ["D", "W", "M", "Y"]
        is_less_than_day = result.group(2) == "PT"
        interval = result.group(4)
        epoch_time_start_string = result.group(1) or result.group(5)
        has_starting_or_ending = bool(len(epoch_time_start_string or ""))

        def sort_day_week() -> int:
            if has_starting_or_ending:
                return pos["LAST"]
            if is_less_than_day:
                return pos["SECOND"]
            return pos["THIRD"]

        def sort_interval() -> float:
            if is_less_than_day:
                return second_minute_hour.index(interval)
            return day_week_month_year.index(interval)

        # 0: all "PT" values should come before "P" values (i.e, PT10M)
        # 1: order values within the above arrays ("D" before "W")
        # 2: sort by numeric value (PT10M before PT15M)
        # 3: sort by any week starting/ending values
        plist = {
            0: sort_day_week(),
            1: pos["SECOND"] if is_less_than_day else pos["THIRD"],
            2: sort_interval(),
            3: float(result.group(3)),
        }

        return plist.get(index, 0)

    @classmethod
    def get_time_grain_expressions(cls) -> Dict[Optional[str], str]:
        """
        Return a dict of all supported time grains including any potential added grains
        but excluding any potentially disabled grains in the config file.

        :return: All time grain expressions supported by the engine
        """
        # TODO: use @memoize decorator or similar to avoid recomputation on every call
        time_grain_expressions = cls._time_grain_expressions.copy()
        grain_addon_expressions = current_app.config["TIME_GRAIN_ADDON_EXPRESSIONS"]
        time_grain_expressions.update(grain_addon_expressions.get(cls.engine, {}))
        denylist: List[str] = current_app.config["TIME_GRAIN_DENYLIST"]
        for key in denylist:
            time_grain_expressions.pop(key)

        return dict(
            sorted(
                time_grain_expressions.items(),
                key=lambda x: (
                    cls._sort_time_grains(x, 0),
                    cls._sort_time_grains(x, 1),
                    cls._sort_time_grains(x, 2),
                    cls._sort_time_grains(x, 3),
                ),
            )
        )

    @classmethod
    def fetch_data(
        cls, cursor: Any, limit: Optional[int] = None
    ) -> List[Tuple[Any, ...]]:
        """

        :param cursor: Cursor instance
        :param limit: Maximum number of rows to be returned by the cursor
        :return: Result of query
        """
        if cls.arraysize:
            cursor.arraysize = cls.arraysize
        try:
            if cls.limit_method == LimitMethod.FETCH_MANY and limit:
                return cursor.fetchmany(limit)
            return cursor.fetchall()
        except Exception as ex:
            raise cls.get_dbapi_mapped_exception(ex) from ex

    @classmethod
    def expand_data(
        cls, columns: List[ResultSetColumnType], data: List[Dict[Any, Any]]
    ) -> Tuple[
        List[ResultSetColumnType], List[Dict[Any, Any]], List[ResultSetColumnType]
    ]:
        """
        Some engines support expanding nested fields. See implementation in Presto
        spec for details.

        :param columns: columns selected in the query
        :param data: original data set
        :return: list of all columns(selected columns and their nested fields),
                 expanded data set, listed of nested fields
        """
        return columns, data, []

    @classmethod
    def alter_new_orm_column(cls, orm_col: "TableColumn") -> None:
        """Allow altering default column attributes when first detected/added

        For instance special column like `__time` for Druid can be
        set to is_dttm=True. Note that this only gets called when new
        columns are detected/created"""
        # TODO: Fix circular import caused by importing TableColumn

    @classmethod
    def epoch_to_dttm(cls) -> str:
        """
        SQL expression that converts epoch (seconds) to datetime that can be used in a
        query. The reference column should be denoted as `{col}` in the return
        expression, e.g. "FROM_UNIXTIME({col})"

        :return: SQL Expression
        """
        raise NotImplementedError()

    @classmethod
    def epoch_ms_to_dttm(cls) -> str:
        """
        SQL expression that converts epoch (milliseconds) to datetime that can be used
        in a query.

        :return: SQL Expression
        """
        return cls.epoch_to_dttm().replace("{col}", "({col}/1000)")

    @classmethod
    def get_datatype(cls, type_code: Any) -> Optional[str]:
        """
        Change column type code from cursor description to string representation.

        :param type_code: Type code from cursor description
        :return: String representation of type code
        """
        if isinstance(type_code, str) and type_code != "":
            return type_code.upper()
        return None

    @classmethod
    def normalize_indexes(cls, indexes: List[Dict[str, Any]]) -> List[Dict[str, Any]]:
        """
        Normalizes indexes for more consistency across db engines

        noop by default

        :param indexes: Raw indexes as returned by SQLAlchemy
        :return: cleaner, more aligned index definition
        """
        return indexes

    @classmethod
    def extra_table_metadata(  # pylint: disable=unused-argument
        cls,
        database: Database,
        table_name: str,
        schema_name: Optional[str],
    ) -> Dict[str, Any]:
        """
        Returns engine-specific table metadata

        :param database: Database instance
        :param table_name: Table name
        :param schema_name: Schema name
        :return: Engine-specific table metadata
        """
        # TODO: Fix circular import caused by importing Database
        return {}

    @classmethod
    def apply_limit_to_sql(
        cls, sql: str, limit: int, database: Database, force: bool = False
    ) -> str:
        """
        Alters the SQL statement to apply a LIMIT clause

        :param sql: SQL query
        :param limit: Maximum number of rows to be returned by the query
        :param database: Database instance
        :return: SQL query with limit clause
        """
        # TODO: Fix circular import caused by importing Database
        if cls.limit_method == LimitMethod.WRAP_SQL:
            sql = sql.strip("\t\n ;")
            qry = (
                select("*")
                .select_from(TextAsFrom(text(sql), ["*"]).alias("inner_qry"))
                .limit(limit)
            )
            return database.compile_sqla_query(qry)

        if cls.limit_method == LimitMethod.FORCE_LIMIT:
            parsed_query = sql_parse.ParsedQuery(sql)
            sql = parsed_query.set_or_update_query_limit(limit, force=force)

        return sql

    @classmethod
    def apply_top_to_sql(cls, sql: str, limit: int) -> str:
        """
        Alters the SQL statement to apply a TOP clause
        :param limit: Maximum number of rows to be returned by the query
        :param sql: SQL query
        :return: SQL query with top clause
        """

        cte = None
        sql_remainder = None
        sql = sql.strip(" \t\n;")
        sql_statement = sqlparse.format(sql, strip_comments=True)
        query_limit: Optional[int] = sql_parse.extract_top_from_query(
            sql_statement, cls.top_keywords
        )
        if not limit:
            final_limit = query_limit
        elif int(query_limit or 0) < limit and query_limit is not None:
            final_limit = query_limit
        else:
            final_limit = limit
        if not cls.allows_cte_in_subquery:
            cte, sql_remainder = sql_parse.get_cte_remainder_query(sql_statement)
        if cte:
            str_statement = str(sql_remainder)
            cte = cte + "\n"
        else:
            cte = ""
            str_statement = str(sql)
        str_statement = str_statement.replace("\n", " ").replace("\r", "")

        tokens = str_statement.rstrip().split(" ")
        tokens = [token for token in tokens if token]
        if cls.top_not_in_sql(str_statement):
            selects = [
                i
                for i, word in enumerate(tokens)
                if word.upper() in cls.select_keywords
            ]
            first_select = selects[0]
            tokens.insert(first_select + 1, "TOP")
            tokens.insert(first_select + 2, str(final_limit))

        next_is_limit_token = False
        new_tokens = []

        for token in tokens:
            if token in cls.top_keywords:
                next_is_limit_token = True
            elif next_is_limit_token:
                if token.isdigit():
                    token = str(final_limit)
                    next_is_limit_token = False
            new_tokens.append(token)
        sql = " ".join(new_tokens)
        return cte + sql

    @classmethod
    def top_not_in_sql(cls, sql: str) -> bool:
        for top_word in cls.top_keywords:
            if top_word.upper() in sql.upper():
                return False
        return True

    @classmethod
    def get_limit_from_sql(cls, sql: str) -> Optional[int]:
        """
        Extract limit from SQL query

        :param sql: SQL query
        :return: Value of limit clause in query
        """
        parsed_query = sql_parse.ParsedQuery(sql)
        return parsed_query.limit

    @classmethod
    def set_or_update_query_limit(cls, sql: str, limit: int) -> str:
        """
        Create a query based on original query but with new limit clause

        :param sql: SQL query
        :param limit: New limit to insert/replace into query
        :return: Query with new limit
        """
        parsed_query = sql_parse.ParsedQuery(sql)
        return parsed_query.set_or_update_query_limit(limit)

    @classmethod
    def get_cte_query(cls, sql: str) -> Optional[str]:
        """
        Convert the input CTE based SQL to the SQL for virtual table conversion

        :param sql: SQL query
        :return: CTE with the main select query aliased as `__cte`

        """
        if not cls.allows_cte_in_subquery:
            stmt = sqlparse.parse(sql)[0]

            # The first meaningful token for CTE will be with WITH
            idx, token = stmt.token_next(-1, skip_ws=True, skip_cm=True)
            if not (token and token.ttype == CTE):
                return None
            idx, token = stmt.token_next(idx)
            idx = stmt.token_index(token) + 1

            # extract rest of the SQLs after CTE
            remainder = "".join(str(token) for token in stmt.tokens[idx:]).strip()
            return f"WITH {token.value},\n{CTE_ALIAS} AS (\n{remainder}\n)"

        return None

    @classmethod
    def df_to_sql(
        cls,
        database: Database,
        table: Table,
        df: pd.DataFrame,
        to_sql_kwargs: Dict[str, Any],
    ) -> None:
        """
        Upload data from a Pandas DataFrame to a database.

        For regular engines this calls the `pandas.DataFrame.to_sql` method. Can be
        overridden for engines that don't work well with this method, e.g. Hive and
        BigQuery.

        Note this method does not create metadata for the table.

        :param database: The database to upload the data to
        :param table: The table to upload the data to
        :param df: The dataframe with data to be uploaded
        :param to_sql_kwargs: The kwargs to be passed to pandas.DataFrame.to_sql` method
        """

        to_sql_kwargs["name"] = table.table

        if table.schema:
            # Only add schema when it is preset and non empty.
            to_sql_kwargs["schema"] = table.schema

        with cls.get_engine(database) as engine:
            if engine.dialect.supports_multivalues_insert:
                to_sql_kwargs["method"] = "multi"

            df.to_sql(con=engine, **to_sql_kwargs)

    @classmethod
    def convert_dttm(  # pylint: disable=unused-argument
        cls, target_type: str, dttm: datetime, db_extra: Optional[Dict[str, Any]] = None
    ) -> Optional[str]:
        """
        Convert a Python `datetime` object to a SQL expression.

        :param target_type: The target type of expression
        :param dttm: The datetime object
        :param db_extra: The database extra object
        :return: The SQL expression
        """
        return None

    @classmethod
    def handle_cursor(cls, cursor: Any, query: Query, session: Session) -> None:
        """Handle a live cursor between the execute and fetchall calls

        The flow works without this method doing anything, but it allows
        for handling the cursor and updating progress information in the
        query object"""
        # TODO: Fix circular import error caused by importing sql_lab.Query

    @classmethod
    def extract_error_message(cls, ex: Exception) -> str:
        return f"{cls.engine} error: {cls._extract_error_message(ex)}"

    @classmethod
    def _extract_error_message(cls, ex: Exception) -> str:
        """Extract error message for queries"""
        return utils.error_msg_from_exception(ex)

    @classmethod
    def extract_errors(
        cls, ex: Exception, context: Optional[Dict[str, Any]] = None
    ) -> List[SupersetError]:
        raw_message = cls._extract_error_message(ex)

        context = context or {}
        for regex, (message, error_type, extra) in cls.custom_errors.items():
            match = regex.search(raw_message)
            if match:
                params = {**context, **match.groupdict()}
                extra["engine_name"] = cls.engine_name
                return [
                    SupersetError(
                        error_type=error_type,
                        message=message % params,
                        level=ErrorLevel.ERROR,
                        extra=extra,
                    )
                ]

        return [
            SupersetError(
                error_type=SupersetErrorType.GENERIC_DB_ENGINE_ERROR,
                message=cls._extract_error_message(ex),
                level=ErrorLevel.ERROR,
                extra={"engine_name": cls.engine_name},
            )
        ]

    @classmethod
    def adjust_database_uri(  # pylint: disable=unused-argument
        cls,
        uri: URL,
        selected_schema: Optional[str],
    ) -> URL:
        """
        Return a modified URL with a new database component.

        The URI here represents the URI as entered when saving the database,
        ``selected_schema`` is the schema currently active presumably in
        the SQL Lab dropdown. Based on that, for some database engine,
        we can return a new altered URI that connects straight to the
        active schema, meaning the users won't have to prefix the object
        names by the schema name.

        Some databases engines have 2 level of namespacing: database and
        schema (postgres, oracle, mssql, ...)
        For those it's probably better to not alter the database
        component of the URI with the schema name, it won't work.

        Some database drivers like Presto accept '{catalog}/{schema}' in
        the database component of the URL, that can be handled here.
        """
        return uri

    @classmethod
    def patch(cls) -> None:
        """
        TODO: Improve docstring and refactor implementation in Hive
        """

    @classmethod
    def get_schema_names(cls, inspector: Inspector) -> List[str]:
        """
        Get all schemas from database

        :param inspector: SqlAlchemy inspector
        :return: All schemas in the database
        """
        return sorted(inspector.get_schema_names())

    @classmethod
    def get_table_names(  # pylint: disable=unused-argument
        cls,
        database: Database,
        inspector: Inspector,
        schema: Optional[str],
    ) -> Set[str]:
        """
        Get all the real table names within the specified schema.

        Per the SQLAlchemy definition if the schema is omitted the database’s default
        schema is used, however some dialects infer the request as schema agnostic.

        :param database: The database to inspect
        :param inspector: The SQLAlchemy inspector
        :param schema: The schema to inspect
        :returns: The physical table names
        """

        try:
            tables = set(inspector.get_table_names(schema))
        except Exception as ex:
            raise cls.get_dbapi_mapped_exception(ex) from ex

        if schema and cls.try_remove_schema_from_table_name:
            tables = {re.sub(f"^{schema}\\.", "", table) for table in tables}
        return tables

    @classmethod
    def get_view_names(  # pylint: disable=unused-argument
        cls,
        database: Database,
        inspector: Inspector,
        schema: Optional[str],
    ) -> Set[str]:
        """
        Get all the view names within the specified schema.

        Per the SQLAlchemy definition if the schema is omitted the database’s default
        schema is used, however some dialects infer the request as schema agnostic.

        :param database: The database to inspect
        :param inspector: The SQLAlchemy inspector
        :param schema: The schema to inspect
        :returns: The view names
        """

        try:
            views = set(inspector.get_view_names(schema))
        except Exception as ex:
            raise cls.get_dbapi_mapped_exception(ex) from ex

        if schema and cls.try_remove_schema_from_table_name:
            views = {re.sub(f"^{schema}\\.", "", view) for view in views}
        return views

    @classmethod
    def get_table_comment(
        cls, inspector: Inspector, table_name: str, schema: Optional[str]
    ) -> Optional[str]:
        """
        Get comment of table from a given schema and table

        :param inspector: SqlAlchemy Inspector instance
        :param table_name: Table name
        :param schema: Schema name. If omitted, uses default schema for database
        :return: comment of table
        """
        comment = None
        try:
            comment = inspector.get_table_comment(table_name, schema)
            comment = comment.get("text") if isinstance(comment, dict) else None
        except NotImplementedError:
            # It's expected that some dialects don't implement the comment method
            pass
        except Exception as ex:  # pylint: disable=broad-except
            logger.error("Unexpected error while fetching table comment", exc_info=True)
            logger.exception(ex)
        return comment

    @classmethod
    def get_columns(
        cls, inspector: Inspector, table_name: str, schema: Optional[str]
    ) -> List[Dict[str, Any]]:
        """
        Get all columns from a given schema and table

        :param inspector: SqlAlchemy Inspector instance
        :param table_name: Table name
        :param schema: Schema name. If omitted, uses default schema for database
        :return: All columns in table
        """
        return inspector.get_columns(table_name, schema)

    @classmethod
    def get_metrics(  # pylint: disable=unused-argument
        cls,
        database: Database,
        inspector: Inspector,
        table_name: str,
        schema: Optional[str],
    ) -> List[MetricType]:
        """
        Get all metrics from a given schema and table.
        """
        return [
            {
                "metric_name": "count",
                "verbose_name": "COUNT(*)",
                "metric_type": "count",
                "expression": "COUNT(*)",
            }
        ]

    @classmethod
    def where_latest_partition(  # pylint: disable=too-many-arguments,unused-argument
        cls,
        table_name: str,
        schema: Optional[str],
        database: Database,
        query: Select,
        columns: Optional[List[Dict[str, str]]] = None,
    ) -> Optional[Select]:
        """
        Add a where clause to a query to reference only the most recent partition

        :param table_name: Table name
        :param schema: Schema name
        :param database: Database instance
        :param query: SqlAlchemy query
        :param columns: List of TableColumns
        :return: SqlAlchemy query with additional where clause referencing the latest
        partition
        """
        # TODO: Fix circular import caused by importing Database, TableColumn
        return None

    @classmethod
    def _get_fields(cls, cols: List[Dict[str, Any]]) -> List[Any]:
        return [column(c["name"]) for c in cols]

    @classmethod
    def select_star(  # pylint: disable=too-many-arguments,too-many-locals
        cls,
        database: Database,
        table_name: str,
        engine: Engine,
        schema: Optional[str] = None,
        limit: int = 100,
        show_cols: bool = False,
        indent: bool = True,
        latest_partition: bool = True,
        cols: Optional[List[Dict[str, Any]]] = None,
    ) -> str:
        """
        Generate a "SELECT * from [schema.]table_name" query with appropriate limit.

        WARNING: expects only unquoted table and schema names.

        :param database: Database instance
        :param table_name: Table name, unquoted
        :param engine: SqlAlchemy Engine instance
        :param schema: Schema, unquoted
        :param limit: limit to impose on query
        :param show_cols: Show columns in query; otherwise use "*"
        :param indent: Add indentation to query
        :param latest_partition: Only query the latest partition
        :param cols: Columns to include in query
        :return: SQL query
        """
        # pylint: disable=redefined-outer-name
        fields: Union[str, List[Any]] = "*"
        cols = cols or []
        if (show_cols or latest_partition) and not cols:
            cols = database.get_columns(table_name, schema)

        if show_cols:
            fields = cls._get_fields(cols)
        quote = engine.dialect.identifier_preparer.quote
        if schema:
            full_table_name = quote(schema) + "." + quote(table_name)
        else:
            full_table_name = quote(table_name)

        qry = select(fields).select_from(text(full_table_name))

        if limit:
            qry = qry.limit(limit)
        if latest_partition:
            partition_query = cls.where_latest_partition(
                table_name, schema, database, qry, columns=cols
            )
            if partition_query is not None:
                qry = partition_query
        sql = database.compile_sqla_query(qry)
        if indent:
            sql = sqlparse.format(sql, reindent=True)
        return sql

    @classmethod
    def estimate_statement_cost(cls, statement: str, cursor: Any) -> Dict[str, Any]:
        """
        Generate a SQL query that estimates the cost of a given statement.

        :param statement: A single SQL statement
        :param cursor: Cursor instance
        :return: Dictionary with different costs
        """
        raise Exception("Database does not support cost estimation")

    @classmethod
    def query_cost_formatter(
        cls, raw_cost: List[Dict[str, Any]]
    ) -> List[Dict[str, str]]:
        """
        Format cost estimate.

        :param raw_cost: Raw estimate from `estimate_query_cost`
        :return: Human readable cost estimate
        """
        raise Exception("Database does not support cost estimation")

    @classmethod
    def process_statement(cls, statement: str, database: Database) -> str:
        """
        Process a SQL statement by stripping and mutating it.

        :param statement: A single SQL statement
        :param database: Database instance
        :return: Dictionary with different costs
        """
        parsed_query = ParsedQuery(statement)
        sql = parsed_query.stripped()
        sql_query_mutator = current_app.config["SQL_QUERY_MUTATOR"]
        mutate_after_split = current_app.config["MUTATE_AFTER_SPLIT"]
        if sql_query_mutator and not mutate_after_split:
            sql = sql_query_mutator(
                sql,
                user_name=get_username(),  # TODO(john-bodley): Deprecate in 3.0.
                security_manager=security_manager,
                database=database,
            )

        return sql

    @classmethod
    def estimate_query_cost(
        cls,
        database: Database,
        schema: str,
        sql: str,
        source: Optional[utils.QuerySource] = None,
    ) -> List[Dict[str, Any]]:
        """
        Estimate the cost of a multiple statement SQL query.

        :param database: Database instance
        :param schema: Database schema
        :param sql: SQL query with possibly multiple statements
        :param source: Source of the query (eg, "sql_lab")
        """
        extra = database.get_extra() or {}
        if not cls.get_allow_cost_estimate(extra):
            raise Exception("Database does not support cost estimation")

        parsed_query = sql_parse.ParsedQuery(sql)
        statements = parsed_query.get_statements()

        costs = []
        with database.get_raw_connection(schema=schema, source=source) as conn:
            cursor = conn.cursor()
            for statement in statements:
                processed_statement = cls.process_statement(statement, database)
                costs.append(cls.estimate_statement_cost(processed_statement, cursor))

        return costs

    @classmethod
    def get_url_for_impersonation(
        cls, url: URL, impersonate_user: bool, username: Optional[str]
    ) -> URL:
        """
        Return a modified URL with the username set.

        :param url: SQLAlchemy URL object
        :param impersonate_user: Flag indicating if impersonation is enabled
        :param username: Effective username
        """
        if impersonate_user and username is not None:
            url = url.set(username=username)

        return url

    @classmethod
    def update_impersonation_config(
        cls,
        connect_args: Dict[str, Any],
        uri: str,
        username: Optional[str],
    ) -> None:
        """
        Update a configuration dictionary
        that can set the correct properties for impersonating users

        :param connect_args: config to be updated
        :param uri: URI
        :param username: Effective username
        :return: None
        """

    @classmethod
    def execute(  # pylint: disable=unused-argument
        cls,
        cursor: Any,
        query: str,
        **kwargs: Any,
    ) -> None:
        """
        Execute a SQL query

        :param cursor: Cursor instance
        :param query: Query to execute
        :param kwargs: kwargs to be passed to cursor.execute()
        :return:
        """
        if not cls.allows_sql_comments:
            query = sql_parse.strip_comments_from_sql(query)

        if cls.arraysize:
            cursor.arraysize = cls.arraysize
        try:
            cursor.execute(query)
        except Exception as ex:
            raise cls.get_dbapi_mapped_exception(ex) from ex

    @classmethod
    def make_label_compatible(cls, label: str) -> Union[str, quoted_name]:
        """
        Conditionally mutate and/or quote a sqlalchemy expression label. If
        force_column_alias_quotes is set to True, return the label as a
        sqlalchemy.sql.elements.quoted_name object to ensure that the select query
        and query results have same case. Otherwise, return the mutated label as a
        regular string. If maximum supported column name length is exceeded,
        generate a truncated label by calling truncate_label().

        :param label: expected expression label/alias
        :return: conditionally mutated label supported by the db engine
        """
        label_mutated = cls._mutate_label(label)
        if (
            cls.max_column_name_length
            and len(label_mutated) > cls.max_column_name_length
        ):
            label_mutated = cls._truncate_label(label)
        if cls.force_column_alias_quotes:
            label_mutated = quoted_name(label_mutated, True)
        return label_mutated

    @classmethod
    def get_sqla_column_type(
        cls,
        column_type: Optional[str],
        column_type_mappings: Tuple[ColumnTypeMapping, ...] = column_type_mappings,
    ) -> Optional[Tuple[TypeEngine, GenericDataType]]:
        """
        Return a sqlalchemy native column type that corresponds to the column type
        defined in the data source (return None to use default type inferred by
        SQLAlchemy). Override `column_type_mappings` for specific needs
        (see MSSQL for example of NCHAR/NVARCHAR handling).

        :param column_type: Column type returned by inspector
        :param column_type_mappings: Maps from string to SqlAlchemy TypeEngine
        :return: SqlAlchemy column type
        """
        if not column_type:
            return None
        for regex, sqla_type, generic_type in column_type_mappings:
            match = regex.match(column_type)
            if not match:
                continue
            if callable(sqla_type):
                return sqla_type(match), generic_type
            return sqla_type, generic_type
        return None

    @staticmethod
    def _mutate_label(label: str) -> str:
        """
        Most engines support mixed case aliases that can include numbers
        and special characters, like commas, parentheses etc. For engines that
        have restrictions on what types of aliases are supported, this method
        can be overridden to ensure that labels conform to the engine's
        limitations. Mutated labels should be deterministic (input label A always
        yields output label X) and unique (input labels A and B don't yield the same
        output label X).

        :param label: Preferred expression label
        :return: Conditionally mutated label
        """
        return label

    @classmethod
    def _truncate_label(cls, label: str) -> str:
        """
        In the case that a label exceeds the max length supported by the engine,
        this method is used to construct a deterministic and unique label based on
        the original label. By default, this returns a md5 hash of the original label,
        conditionally truncated if the length of the hash exceeds the max column length
        of the engine.

        :param label: Expected expression label
        :return: Truncated label
        """
        label = md5_sha_from_str(label)
        # truncate hash if it exceeds max length
        if cls.max_column_name_length and len(label) > cls.max_column_name_length:
            label = label[: cls.max_column_name_length]
        return label

    @classmethod
    def column_datatype_to_string(
        cls, sqla_column_type: TypeEngine, dialect: Dialect
    ) -> str:
        """
        Convert sqlalchemy column type to string representation.
        By default, removes collation and character encoding info to avoid
        unnecessarily long datatypes.

        :param sqla_column_type: SqlAlchemy column type
        :param dialect: Sqlalchemy dialect
        :return: Compiled column type
        """
        sqla_column_type = sqla_column_type.copy()
        if hasattr(sqla_column_type, "collation"):
            sqla_column_type.collation = None
        if hasattr(sqla_column_type, "charset"):
            sqla_column_type.charset = None
        return sqla_column_type.compile(dialect=dialect).upper()

    @classmethod
    def get_function_names(  # pylint: disable=unused-argument
        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 useable in the database
        """
        return []

    @staticmethod
    def pyodbc_rows_to_tuples(data: List[Any]) -> List[Tuple[Any, ...]]:
        """
        Convert pyodbc.Row objects from `fetch_data` to tuples.

        :param data: List of tuples or pyodbc.Row objects
        :return: List of tuples
        """
        if data and type(data[0]).__name__ == "Row":
            data = [tuple(row) for row in data]
        return data

    @staticmethod
    def mutate_db_for_connection_test(  # pylint: disable=unused-argument
        database: Database,
    ) -> None:
        """
        Some databases require passing additional parameters for validating database
        connections. This method makes it possible to mutate the database instance prior
        to testing if a connection is ok.

        :param database: instance to be mutated
        """
        return None

    @staticmethod
    def get_extra_params(database: Database) -> Dict[str, Any]:
        """
        Some databases require adding elements to connection parameters,
        like passing certificates to `extra`. This can be done here.

        :param database: database instance from which to extract extras
        :raises CertificateException: If certificate is not valid/unparseable
        """
        extra: Dict[str, Any] = {}
        if database.extra:
            try:
                extra = json.loads(database.extra)
            except json.JSONDecodeError as ex:
                logger.error(ex, exc_info=True)
                raise ex
        return extra

    @staticmethod
    def update_params_from_encrypted_extra(  # pylint: disable=invalid-name
        database: Database, params: Dict[str, Any]
    ) -> None:
        """
        Some databases require some sensitive information which do not conform to
        the username:password syntax normally used by SQLAlchemy.

        :param database: database instance from which to extract extras
        :param params: params to be updated
        """
        if not database.encrypted_extra:
            return
        try:
            encrypted_extra = json.loads(database.encrypted_extra)
            params.update(encrypted_extra)
        except json.JSONDecodeError as ex:
            logger.error(ex, exc_info=True)
            raise ex

    @classmethod
    def is_readonly_query(cls, parsed_query: ParsedQuery) -> bool:
        """Pessimistic readonly, 100% sure statement won't mutate anything"""
        return (
            parsed_query.is_select()
            or parsed_query.is_explain()
            or parsed_query.is_show()
        )

    @classmethod
    def is_select_query(cls, parsed_query: ParsedQuery) -> bool:
        """
        Determine if the statement should be considered as SELECT statement.
        Some query dialects do not contain "SELECT" word in queries (eg. Kusto)
        """
        return parsed_query.is_select()

    @classmethod
    def get_column_spec(  # pylint: disable=unused-argument
        cls,
        native_type: Optional[str],
        db_extra: Optional[Dict[str, Any]] = None,
        source: utils.ColumnTypeSource = utils.ColumnTypeSource.GET_TABLE,
        column_type_mappings: Tuple[ColumnTypeMapping, ...] = column_type_mappings,
    ) -> Optional[ColumnSpec]:
        """
        Converts native database type to sqlalchemy column type.
        :param native_type: Native database type
        :param db_extra: The database extra object
        :param source: Type coming from the database table or cursor description
        :param column_type_mappings: Maps from string to SqlAlchemy TypeEngine
        :return: ColumnSpec object
        """
        col_types = cls.get_sqla_column_type(
            native_type, column_type_mappings=column_type_mappings
        )
        if col_types:
            column_type, generic_type = col_types
            is_dttm = generic_type == GenericDataType.TEMPORAL
            return ColumnSpec(
                sqla_type=column_type, generic_type=generic_type, is_dttm=is_dttm
            )
        return None

    # pylint: disable=unused-argument
    @classmethod
    def prepare_cancel_query(cls, query: Query, session: Session) -> None:
        """
        Some databases may acquire the query cancelation id after the query
        cancelation request has been received. For those cases, the db engine spec
        can record the cancelation intent so that the query can either be stopped
        prior to execution, or canceled once the query id is acquired.
        """
        return None

    @classmethod
    def has_implicit_cancel(cls) -> bool:
        """
        Return True if the live cursor handles the implicit cancelation of the query,
        False otherwise.

        :return: Whether the live cursor implicitly cancels the query
        :see: handle_cursor
        """

        return False

    @classmethod
    def get_cancel_query_id(  # pylint: disable=unused-argument
        cls,
        cursor: Any,
        query: Query,
    ) -> Optional[str]:
        """
        Select identifiers from the database engine that uniquely identifies the
        queries to cancel. The identifier is typically a session id, process id
        or similar.

        :param cursor: Cursor instance in which the query will be executed
        :param query: Query instance
        :return: Query identifier
        """

        return None

    @classmethod
    def cancel_query(  # pylint: disable=unused-argument
        cls,
        cursor: Any,
        query: Query,
        cancel_query_id: str,
    ) -> bool:
        """
        Cancel query in the underlying database.

        :param cursor: New cursor instance to the db of the query
        :param query: Query instance
        :param cancel_query_id: Value returned by get_cancel_query_payload or set in
        other life-cycle methods of the query
        :return: True if query cancelled successfully, False otherwise
        """

        return False

    @classmethod
    def parse_sql(cls, sql: str) -> List[str]:
        return [str(s).strip(" ;") for s in sqlparse.parse(sql)]

    @classmethod
    def get_impersonation_key(cls, user: Optional[User]) -> Any:
        """
        Construct an impersonation key, by default it's the given username.

        :param user: logged in user

        :returns: username if given user is not null
        """
        return user.username if user else None

    @classmethod
    def mask_encrypted_extra(cls, encrypted_extra: Optional[str]) -> Optional[str]:
        """
        Mask ``encrypted_extra``.

        This is used to remove any sensitive data in ``encrypted_extra`` when presenting
        it to the user. For example, a private key might be replaced with a masked value
        "XXXXXXXXXX". If the masked value is changed the corresponding entry is updated,
        otherwise the old value is used (see ``unmask_encrypted_extra`` below).
        """
        return encrypted_extra

    # pylint: disable=unused-argument
    @classmethod
    def unmask_encrypted_extra(
        cls, old: Optional[str], new: Optional[str]
    ) -> Optional[str]:
        """
        Remove masks from ``encrypted_extra``.

        This method allows reusing existing values from the current encrypted extra on
        updates. It's useful for reusing masked passwords, allowing keys to be updated
        without having to provide sensitive data to the client.
        """
        return new

    @classmethod
    def get_public_information(cls) -> Dict[str, Any]:
        """
        Construct a Dict with properties we want to expose.

        :returns: Dict with properties of our class like supports_file_upload
        and disable_ssh_tunneling
        """
        return {
            "supports_file_upload": cls.supports_file_upload,
            "disable_ssh_tunneling": cls.disable_ssh_tunneling,
        }


# schema for adding a database by providing parameters instead of the
# full SQLAlchemy URI
class BasicParametersSchema(Schema):
    username = fields.String(required=True, allow_none=True, description=__("Username"))
    password = fields.String(allow_none=True, description=__("Password"))
    host = fields.String(required=True, description=__("Hostname or IP address"))
    port = fields.Integer(
        required=True,
        description=__("Database port"),
        validate=Range(min=0, max=2**16, max_inclusive=False),
    )
    database = fields.String(required=True, description=__("Database name"))
    query = fields.Dict(
        keys=fields.Str(), values=fields.Raw(), description=__("Additional parameters")
    )
    encryption = fields.Boolean(
        required=False, description=__("Use an encrypted connection to the database")
    )


class BasicParametersType(TypedDict, total=False):
    username: Optional[str]
    password: Optional[str]
    host: str
    port: int
    database: str
    query: Dict[str, Any]
    encryption: bool


class BasicPropertiesType(TypedDict):
    parameters: BasicParametersType


class BasicParametersMixin:
    """
    Mixin for configuring DB engine specs via a dictionary.

    With this mixin the SQLAlchemy engine can be configured through
    individual parameters, instead of the full SQLAlchemy URI. This
    mixin is for the most common pattern of URI:

        engine+driver://user:password@host:port/dbname[?key=value&key=value...]

    """

    # schema describing the parameters used to configure the DB
    parameters_schema = BasicParametersSchema()

    # recommended driver name for the DB engine spec
    default_driver = ""

    # placeholder with the SQLAlchemy URI template
    sqlalchemy_uri_placeholder = (
        "engine+driver://user:password@host:port/dbname[?key=value&key=value...]"
    )

    # query parameter to enable encryption in the database connection
    # for Postgres this would be `{"sslmode": "verify-ca"}`, eg.
    encryption_parameters: Dict[str, str] = {}

    @classmethod
    def build_sqlalchemy_uri(  # pylint: disable=unused-argument
        cls,
        parameters: BasicParametersType,
        encrypted_extra: Optional[Dict[str, str]] = None,
    ) -> str:
        # make a copy so that we don't update the original
        query = parameters.get("query", {}).copy()
        if parameters.get("encryption"):
            if not cls.encryption_parameters:
                raise Exception("Unable to build a URL with encryption enabled")
            query.update(cls.encryption_parameters)

        return str(
            URL(
                f"{cls.engine}+{cls.default_driver}".rstrip("+"),  # type: ignore
                username=parameters.get("username"),
                password=parameters.get("password"),
                host=parameters["host"],
                port=parameters["port"],
                database=parameters["database"],
                query=query,
            )
        )

    @classmethod
    def get_parameters_from_uri(  # pylint: disable=unused-argument
        cls, uri: str, encrypted_extra: Optional[Dict[str, Any]] = None
    ) -> BasicParametersType:
        url = make_url_safe(uri)
        query = {
            key: value
            for (key, value) in url.query.items()
            if (key, value) not in cls.encryption_parameters.items()
        }
        encryption = all(
            item in url.query.items() for item in cls.encryption_parameters.items()
        )
        return {
            "username": url.username,
            "password": url.password,
            "host": url.host,
            "port": url.port,
            "database": url.database,
            "query": query,
            "encryption": encryption,
        }

    @classmethod
    def validate_parameters(
        cls, properties: BasicPropertiesType
    ) -> List[SupersetError]:
        """
        Validates any number of parameters, for progressive validation.

        If only the hostname is present it will check if the name is resolvable. As more
        parameters are present in the request, more validation is done.
        """
        errors: List[SupersetError] = []

        required = {"host", "port", "username", "database"}
        parameters = properties.get("parameters", {})
        present = {key for key in parameters if parameters.get(key, ())}
        missing = sorted(required - present)

        if missing:
            errors.append(
                SupersetError(
                    message=f'One or more parameters are missing: {", ".join(missing)}',
                    error_type=SupersetErrorType.CONNECTION_MISSING_PARAMETERS_ERROR,
                    level=ErrorLevel.WARNING,
                    extra={"missing": missing},
                ),
            )

        host = parameters.get("host", None)
        if not host:
            return errors
        if not is_hostname_valid(host):
            errors.append(
                SupersetError(
                    message="The hostname provided can't be resolved.",
                    error_type=SupersetErrorType.CONNECTION_INVALID_HOSTNAME_ERROR,
                    level=ErrorLevel.ERROR,
                    extra={"invalid": ["host"]},
                ),
            )
            return errors

        port = parameters.get("port", None)
        if not port:
            return errors
        try:
            port = int(port)
        except (ValueError, TypeError):
            errors.append(
                SupersetError(
                    message="Port must be a valid integer.",
                    error_type=SupersetErrorType.CONNECTION_INVALID_PORT_ERROR,
                    level=ErrorLevel.ERROR,
                    extra={"invalid": ["port"]},
                ),
            )
        if not (isinstance(port, int) and 0 <= port < 2**16):
            errors.append(
                SupersetError(
                    message=(
                        "The port must be an integer between 0 and 65535 "
                        "(inclusive)."
                    ),
                    error_type=SupersetErrorType.CONNECTION_INVALID_PORT_ERROR,
                    level=ErrorLevel.ERROR,
                    extra={"invalid": ["port"]},
                ),
            )
        elif not is_port_open(host, port):
            errors.append(
                SupersetError(
                    message="The port is closed.",
                    error_type=SupersetErrorType.CONNECTION_PORT_CLOSED_ERROR,
                    level=ErrorLevel.ERROR,
                    extra={"invalid": ["port"]},
                ),
            )

        return errors

    @classmethod
    def parameters_json_schema(cls) -> Any:
        """
        Return configuration parameters as OpenAPI.
        """
        if not cls.parameters_schema:
            return None

        spec = APISpec(
            title="Database Parameters",
            version="1.0.0",
            openapi_version="3.0.2",
            plugins=[MarshmallowPlugin()],
        )
        spec.components.schema(cls.__name__, schema=cls.parameters_schema)
        return spec.to_dict()["components"]["schemas"][cls.__name__]