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"""This module contains an operator to move data from MySQL to Hive."""
from collections import OrderedDict
from tempfile import NamedTemporaryFile
from typing import TYPE_CHECKING, Dict, Optional, Sequence
import MySQLdb
import unicodecsv as csv
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)
:type sql: str
:param hive_table: target Hive table, use dot notation to target a
specific database. (templated)
:type hive_table: str
:param create: whether to create the table if it doesn't exist
:type create: bool
:param recreate: whether to drop and recreate the table at every
execution
:type recreate: bool
:param partition: target partition as a dict of partition columns
and values. (templated)
:type partition: dict
:param delimiter: field delimiter in the file
:type delimiter: str
:param quoting: controls when quotes should be generated by csv writer,
It can take on any of the csv.QUOTE_* constants.
:type quoting: str
:param quotechar: one-character string used to quote fields
containing special characters.
:type quotechar: str
:param escapechar: one-character string used by csv writer to escape
the delimiter or quotechar.
:type escapechar: str
:param mysql_conn_id: source mysql connection
:type mysql_conn_id: str
:param hive_cli_conn_id: Reference to the
:ref:`Hive CLI connection id <howto/connection:hive_cli>`.
:type hive_cli_conn_id: str
:param tblproperties: TBLPROPERTIES of the hive table being created
:type tblproperties: dict
"""
[docs] template_fields: Sequence[str] = ('sql', 'partition', 'hive_table')
[docs] template_ext: Sequence[str] = ('.sql',)
def __init__(
self,
*,
sql: str,
hive_table: str,
create: bool = True,
recreate: bool = False,
partition: Optional[Dict] = None,
delimiter: str = chr(1),
quoting: Optional[str] = None,
quotechar: str = '"',
escapechar: Optional[str] = None,
mysql_conn_id: str = 'mysql_default',
hive_cli_conn_id: str = 'hive_cli_default',
tblproperties: Optional[Dict] = 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
@classmethod
[docs] def type_map(cls, mysql_type: int) -> str:
"""Maps 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)
mysql = MySqlHook(mysql_conn_id=self.mysql_conn_id)
self.log.info("Dumping MySQL query results to local file")
conn = mysql.get_conn()
cursor = conn.cursor()
cursor.execute(self.sql)
with NamedTemporaryFile("wb") as f:
csv_writer = csv.writer(
f,
delimiter=self.delimiter,
quoting=self.quoting,
quotechar=self.quotechar,
escapechar=self.escapechar,
encoding="utf-8",
)
field_dict = OrderedDict()
for field in cursor.description:
field_dict[field[0]] = self.type_map(field[1])
csv_writer.writerows(cursor)
f.flush()
cursor.close()
conn.close()
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,
)