superset/db_engine_specs/postgres.py

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from datetime import datetime
from typing import List, Optional, Tuple, TYPE_CHECKING

from sqlalchemy.dialects.postgresql.base import PGInspector

from superset.db_engine_specs.base import BaseEngineSpec, LimitMethod

if TYPE_CHECKING:
    # prevent circular imports
    from superset.models.core import Database  # pylint: disable=unused-import


class PostgresBaseEngineSpec(BaseEngineSpec):
    """ Abstract class for Postgres 'like' databases """

    engine = ""

    _time_grain_functions = {
        None: "{col}",
        "PT1S": "DATE_TRUNC('second', {col})",
        "PT1M": "DATE_TRUNC('minute', {col})",
        "PT1H": "DATE_TRUNC('hour', {col})",
        "P1D": "DATE_TRUNC('day', {col})",
        "P1W": "DATE_TRUNC('week', {col})",
        "P1M": "DATE_TRUNC('month', {col})",
        "P0.25Y": "DATE_TRUNC('quarter', {col})",
        "P1Y": "DATE_TRUNC('year', {col})",
    }

    @classmethod
    def fetch_data(cls, cursor, limit: int) -> List[Tuple]:
        if not cursor.description:
            return []
        if cls.limit_method == LimitMethod.FETCH_MANY:
            return cursor.fetchmany(limit)
        return cursor.fetchall()

    @classmethod
    def epoch_to_dttm(cls) -> str:
        return "(timestamp 'epoch' + {col} * interval '1 second')"

    @classmethod
    def convert_dttm(cls, target_type: str, dttm: datetime) -> str:
        return "'{}'".format(dttm.strftime("%Y-%m-%d %H:%M:%S"))


class PostgresEngineSpec(PostgresBaseEngineSpec):
    engine = "postgresql"
    max_column_name_length = 63
    try_remove_schema_from_table_name = False

    @classmethod
    def get_table_names(
        cls, database: "Database", inspector: PGInspector, schema: Optional[str]
    ) -> List[str]:
        """Need to consider foreign tables for PostgreSQL"""
        tables = inspector.get_table_names(schema)
        tables.extend(inspector.get_foreign_table_names(schema))
        return sorted(tables)