Source code for airflow.providers.openlineage.utils.sql

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from __future__ import annotations

import logging
from collections import defaultdict
from contextlib import closing
from enum import IntEnum
from typing import TYPE_CHECKING, Dict, List, Optional

from attrs import define
from openlineage.client.facet import SchemaDatasetFacet, SchemaField
from openlineage.client.run import Dataset
from sqlalchemy import Column, MetaData, Table, and_, union_all

if TYPE_CHECKING:
    from sqlalchemy.engine import Engine
    from sqlalchemy.sql import ClauseElement

    from airflow.hooks.base import BaseHook


[docs]logger = logging.getLogger(__name__)


[docs]class ColumnIndex(IntEnum):
    """Enumerates the indices of columns in information schema view."""

[docs]    SCHEMA = 0
[docs]    TABLE_NAME = 1
[docs]    COLUMN_NAME = 2
[docs]    ORDINAL_POSITION = 3
    # Use 'udt_name' which is the underlying type of column
[docs]    UDT_NAME = 4
    # Database is optional as 5th column
[docs]    DATABASE = 5


[docs]TablesHierarchy = Dict[Optional[str], Dict[Optional[str], List[str]]]


@define
[docs]class TableSchema:
    """Temporary object used to construct OpenLineage Dataset."""

[docs]    table: str
[docs]    schema: str | None
[docs]    database: str | None
[docs]    fields: list[SchemaField]

[docs]    def to_dataset(self, namespace: str, database: str | None = None, schema: str | None = None) -> Dataset:
        # Prefix the table name with database and schema name using
        # the format: {database_name}.{table_schema}.{table_name}.
        name = ".".join(
            part
            for part in [self.database or database, self.schema or schema, self.table]
            if part is not None
        )
        return Dataset(
            namespace=namespace,
            name=name,
            facets={"schema": SchemaDatasetFacet(fields=self.fields)} if len(self.fields) > 0 else {},
        )


[docs]def get_table_schemas(
    hook: BaseHook,
    namespace: str,
    schema: str | None,
    database: str | None,
    in_query: str | None,
    out_query: str | None,
) -> tuple[list[Dataset], list[Dataset]]:
    """Query database for table schemas.

    Uses provided hook. Responsibility to provide queries for this function is on particular extractors.
    If query for input or output table isn't provided, the query is skipped.
    """
    # Do not query if we did not get both queries
    if not in_query and not out_query:
        return [], []

    with closing(hook.get_conn()) as conn, closing(conn.cursor()) as cursor:
        if in_query:
            cursor.execute(in_query)
            in_datasets = [x.to_dataset(namespace, database, schema) for x in parse_query_result(cursor)]
        else:
            in_datasets = []
        if out_query:
            cursor.execute(out_query)
            out_datasets = [x.to_dataset(namespace, database, schema) for x in parse_query_result(cursor)]
        else:
            out_datasets = []
    return in_datasets, out_datasets


[docs]def parse_query_result(cursor) -> list[TableSchema]:
    """Fetch results from DB-API 2.0 cursor and creates list of table schemas.

    For each row it creates :class:`TableSchema`.
    """
    schemas: dict = {}
    columns: dict = defaultdict(list)
    for row in cursor.fetchall():
        table_schema_name: str = row[ColumnIndex.SCHEMA]
        table_name: str = row[ColumnIndex.TABLE_NAME]
        table_column: SchemaField = SchemaField(
            name=row[ColumnIndex.COLUMN_NAME],
            type=row[ColumnIndex.UDT_NAME],
            description=None,
        )
        ordinal_position = row[ColumnIndex.ORDINAL_POSITION]
        try:
            table_database = row[ColumnIndex.DATABASE]
        except IndexError:
            table_database = None

        # Attempt to get table schema
        table_key = ".".join(filter(None, [table_database, table_schema_name, table_name]))

        schemas[table_key] = TableSchema(
            table=table_name, schema=table_schema_name, database=table_database, fields=[]
        )
        columns[table_key].append((ordinal_position, table_column))

    for schema in schemas.values():
        table_key = ".".join(filter(None, [schema.database, schema.schema, schema.table]))
        schema.fields = [x for _, x in sorted(columns[table_key])]

    return list(schemas.values())


[docs]def create_information_schema_query(
    columns: list[str],
    information_schema_table_name: str,
    tables_hierarchy: TablesHierarchy,
    uppercase_names: bool = False,
    sqlalchemy_engine: Engine | None = None,
) -> str:
    """Creates query for getting table schemas from information schema."""
    metadata = MetaData(sqlalchemy_engine)
    select_statements = []
    for db, schema_mapping in tables_hierarchy.items():
        schema, table_name = information_schema_table_name.split(".")
        if db:
            schema = f"{db}.{schema}"
        information_schema_table = Table(
            table_name, metadata, *[Column(column) for column in columns], schema=schema
        )
        filter_clauses = create_filter_clauses(schema_mapping, information_schema_table, uppercase_names)
        select_statements.append(information_schema_table.select().filter(*filter_clauses))
    return str(
        union_all(*select_statements).compile(sqlalchemy_engine, compile_kwargs={"literal_binds": True})
    )


[docs]def create_filter_clauses(
    schema_mapping: dict, information_schema_table: Table, uppercase_names: bool = False
) -> ClauseElement:
    """
    Creates comprehensive filter clauses for all tables in one database.

    :param schema_mapping: a dictionary of schema names and list of tables in each
    :param information_schema_table: `sqlalchemy.Table` instance used to construct clauses
        For most SQL dbs it contains `table_name` and `table_schema` columns,
        therefore it is expected the table has them defined.
    :param uppercase_names: if True use schema and table names uppercase
    """
    filter_clauses = []
    for schema, tables in schema_mapping.items():
        filter_clause = information_schema_table.c.table_name.in_(
            name.upper() if uppercase_names else name for name in tables
        )
        if schema:
            filter_clause = and_(information_schema_table.c.table_schema == schema, filter_clause)
        filter_clauses.append(filter_clause)
    return filter_clauses