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"""This module contains an operator to move data from MySQL to Hive."""
from __future__ import annotations
import csv
from contextlib import closing
from tempfile import NamedTemporaryFile
from typing import TYPE_CHECKING, Sequence
import MySQLdb
from airflow.models import BaseOperator
from airflow.providers.apache.hive.hooks.hive import HiveCliHook
from airflow.providers.mysql.hooks.mysql import MySqlHook
if TYPE_CHECKING:
from airflow.utils.context import Context
[docs]class MySqlToHiveOperator(BaseOperator):
"""
Moves data from MySql to Hive.
The operator runs your query against MySQL, stores the file locally
before loading it into a Hive table.
If the ``create`` or ``recreate`` arguments are set to ``True``,
a ``CREATE TABLE`` and ``DROP TABLE`` statements are generated.
Hive data types are inferred from the cursor's metadata. Note that the
table generated in Hive uses ``STORED AS textfile``
which isn't the most efficient serialization format. If a
large amount of data is loaded and/or if the table gets
queried considerably, you may want to use this operator only to
stage the data into a temporary table before loading it into its
final destination using a ``HiveOperator``.
:param sql: SQL query to execute against the MySQL database. (templated)
:param hive_table: target Hive table, use dot notation to target a
specific database. (templated)
:param create: whether to create the table if it doesn't exist
:param recreate: whether to drop and recreate the table at every
execution
:param partition: target partition as a dict of partition columns
and values. (templated)
:param delimiter: field delimiter in the file
:param quoting: controls when quotes should be generated by csv writer,
It can take on any of the csv.QUOTE_* constants.
:param quotechar: one-character string used to quote fields
containing special characters.
:param escapechar: one-character string used by csv writer to escape
the delimiter or quotechar.
:param mysql_conn_id: source mysql connection
:param hive_cli_conn_id: Reference to the
:ref:`Hive CLI connection id <howto/connection:hive_cli>`.
:param hive_auth: optional authentication option passed for the Hive connection
:param tblproperties: TBLPROPERTIES of the hive table being created
"""
[docs] template_fields: Sequence[str] = ("sql", "partition", "hive_table")
[docs] template_ext: Sequence[str] = (".sql",)
[docs] template_fields_renderers = {"sql": "mysql"}
def __init__(
self,
*,
sql: str,
hive_table: str,
create: bool = True,
recreate: bool = False,
partition: dict | None = None,
delimiter: str = chr(1),
quoting: int | None = None,
quotechar: str = '"',
escapechar: str | None = None,
mysql_conn_id: str = "mysql_default",
hive_cli_conn_id: str = "hive_cli_default",
hive_auth: str | None = None,
tblproperties: dict | None = None,
**kwargs,
) -> None:
super().__init__(**kwargs)
self.sql = sql
self.hive_table = hive_table
self.partition = partition
self.create = create
self.recreate = recreate
self.delimiter = str(delimiter)
self.quoting = quoting or csv.QUOTE_MINIMAL
self.quotechar = quotechar
self.escapechar = escapechar
self.mysql_conn_id = mysql_conn_id
self.hive_cli_conn_id = hive_cli_conn_id
self.partition = partition or {}
self.tblproperties = tblproperties
self.hive_auth = hive_auth
@classmethod
[docs] def type_map(cls, mysql_type: int) -> str:
"""Map MySQL type to Hive type."""
types = MySQLdb.constants.FIELD_TYPE
type_map = {
types.BIT: "INT",
types.DECIMAL: "DOUBLE",
types.NEWDECIMAL: "DOUBLE",
types.DOUBLE: "DOUBLE",
types.FLOAT: "DOUBLE",
types.INT24: "INT",
types.LONG: "BIGINT",
types.LONGLONG: "DECIMAL(38,0)",
types.SHORT: "INT",
types.TINY: "SMALLINT",
types.YEAR: "INT",
types.TIMESTAMP: "TIMESTAMP",
}
return type_map.get(mysql_type, "STRING")
[docs] def execute(self, context: Context):
hive = HiveCliHook(hive_cli_conn_id=self.hive_cli_conn_id, auth=self.hive_auth)
mysql = MySqlHook(mysql_conn_id=self.mysql_conn_id)
self.log.info("Dumping MySQL query results to local file")
with NamedTemporaryFile(mode="w", encoding="utf-8") as f:
with closing(mysql.get_conn()) as conn, closing(conn.cursor()) as cursor:
cursor.execute(self.sql)
csv_writer = csv.writer(
f,
delimiter=self.delimiter,
quoting=self.quoting,
quotechar=self.quotechar if self.quoting != csv.QUOTE_NONE else None,
escapechar=self.escapechar,
)
field_dict = {}
if cursor.description is not None:
for field in cursor.description:
field_dict[field[0]] = self.type_map(field[1])
csv_writer.writerows(cursor) # type: ignore[arg-type]
f.flush()
self.log.info("Loading file into Hive")
hive.load_file(
f.name,
self.hive_table,
field_dict=field_dict,
create=self.create,
partition=self.partition,
delimiter=self.delimiter,
recreate=self.recreate,
tblproperties=self.tblproperties,
)