superset/db_engine_specs/trino.py

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# distributed with this work for additional information
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# 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
#
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# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
from datetime import datetime
from typing import Any, Dict, List, Optional
from urllib import parse

import simplejson as json
from sqlalchemy.engine.url import make_url, URL

from superset.db_engine_specs.base import BaseEngineSpec
from superset.utils import core as utils


class TrinoEngineSpec(BaseEngineSpec):
    engine = "trino"
    engine_name = "Trino"

    _time_grain_expressions = {
        None: "{col}",
        "PT1S": "date_trunc('second', CAST({col} AS TIMESTAMP))",
        "PT1M": "date_trunc('minute', CAST({col} AS TIMESTAMP))",
        "PT1H": "date_trunc('hour', CAST({col} AS TIMESTAMP))",
        "P1D": "date_trunc('day', CAST({col} AS TIMESTAMP))",
        "P1W": "date_trunc('week', CAST({col} AS TIMESTAMP))",
        "P1M": "date_trunc('month', CAST({col} AS TIMESTAMP))",
        "P0.25Y": "date_trunc('quarter', CAST({col} AS TIMESTAMP))",
        "P1Y": "date_trunc('year', CAST({col} AS TIMESTAMP))",
        # "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
    }

    @classmethod
    def convert_dttm(cls, target_type: str, dttm: datetime) -> Optional[str]:
        tt = target_type.upper()
        if tt == utils.TemporalType.DATE:
            value = dttm.date().isoformat()
            return f"from_iso8601_date('{value}')"
        if tt == utils.TemporalType.TIMESTAMP:
            value = dttm.isoformat(timespec="microseconds")
            return f"from_iso8601_timestamp('{value}')"
        return None

    @classmethod
    def epoch_to_dttm(cls) -> str:
        return "from_unixtime({col})"

    @classmethod
    def adjust_database_uri(
        cls, uri: URL, selected_schema: Optional[str] = None
    ) -> None:
        database = uri.database
        if selected_schema and database:
            selected_schema = parse.quote(selected_schema, safe="")
            database = database.split("/")[0] + "/" + selected_schema
            uri.database = database

    @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 string
        :param impersonate_user: Flag indicating if impersonation is enabled
        :param username: Effective username
        :return: None
        """
        url = make_url(uri)
        backend_name = url.get_backend_name()

        # Must be Trino connection, enable impersonation, and set optional param
        # auth=LDAP|KERBEROS
        # Set principal_username=$effective_username
        if backend_name == "trino" and username is not None:
            connect_args["user"] = username

    @classmethod
    def modify_url_for_impersonation(
        cls, url: URL, impersonate_user: bool, username: Optional[str]
    ) -> None:
        """
        Modify the SQL Alchemy URL object with the user to impersonate if applicable.
        :param url: SQLAlchemy URL object
        :param impersonate_user: Flag indicating if impersonation is enabled
        :param username: Effective username
        """
        # Do nothing and let update_impersonation_config take care of impersonation

    @classmethod
    def get_allow_cost_estimate(cls, extra: Dict[str, Any]) -> bool:
        return True

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

        :param statement: A single SQL statement
        :param database: Database instance
        :param cursor: Cursor instance
        :param username: Effective username
        :return: JSON response from Trino
        """
        sql = f"EXPLAIN (TYPE IO, FORMAT JSON) {statement}"
        cursor.execute(sql)

        # the output from Trino is a single column and a single row containing
        # JSON:
        #
        #   {
        #     ...
        #     "estimate" : {
        #       "outputRowCount" : 8.73265878E8,
        #       "outputSizeInBytes" : 3.41425774958E11,
        #       "cpuCost" : 3.41425774958E11,
        #       "maxMemory" : 0.0,
        #       "networkCost" : 3.41425774958E11
        #     }
        #   }
        result = json.loads(cursor.fetchone()[0])
        return result

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

        :param raw_cost: JSON estimate from Trino
        :return: Human readable cost estimate
        """

        def humanize(value: Any, suffix: str) -> str:
            try:
                value = int(value)
            except ValueError:
                return str(value)

            prefixes = ["K", "M", "G", "T", "P", "E", "Z", "Y"]
            prefix = ""
            to_next_prefix = 1000
            while value > to_next_prefix and prefixes:
                prefix = prefixes.pop(0)
                value //= to_next_prefix

            return f"{value} {prefix}{suffix}"

        cost = []
        columns = [
            ("outputRowCount", "Output count", " rows"),
            ("outputSizeInBytes", "Output size", "B"),
            ("cpuCost", "CPU cost", ""),
            ("maxMemory", "Max memory", "B"),
            ("networkCost", "Network cost", ""),
        ]
        for row in raw_cost:
            estimate: Dict[str, float] = row.get("estimate", {})
            statement_cost = {}
            for key, label, suffix in columns:
                if key in estimate:
                    statement_cost[label] = humanize(estimate[key], suffix).strip()
            cost.append(statement_cost)

        return cost