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import datetime
[docs]def max_partition(
table, schema="default", field=None, filter_map=None,
metastore_conn_id='metastore_default'):
"""
Gets the max partition for a table.
:param schema: The hive schema the table lives in
:type schema: str
:param table: The hive table you are interested in, supports the dot
notation as in "my_database.my_table", if a dot is found,
the schema param is disregarded
:type table: str
:param metastore_conn_id: The hive connection you are interested in.
If your default is set you don't need to use this parameter.
:type metastore_conn_id: str
:param filter_map: partition_key:partition_value map used for partition filtering,
e.g. {'key1': 'value1', 'key2': 'value2'}.
Only partitions matching all partition_key:partition_value
pairs will be considered as candidates of max partition.
:type filter_map: map
:param field: the field to get the max value from. If there's only
one partition field, this will be inferred
:type field: str
>>> max_partition('airflow.static_babynames_partitioned')
'2015-01-01'
"""
from airflow.hooks.hive_hooks import HiveMetastoreHook
if '.' in table:
schema, table = table.split('.')
hh = HiveMetastoreHook(metastore_conn_id=metastore_conn_id)
return hh.max_partition(
schema=schema, table_name=table, field=field, filter_map=filter_map)
def _closest_date(target_dt, date_list, before_target=None):
"""
This function finds the date in a list closest to the target date.
An optional parameter can be given to get the closest before or after.
:param target_dt: The target date
:type target_dt: datetime.date
:param date_list: The list of dates to search
:type date_list: list[datetime.date]
:param before_target: closest before or after the target
:type before_target: bool or None
:returns: The closest date
:rtype: datetime.date or None
"""
fb = lambda d: target_dt - d if d <= target_dt else datetime.timedelta.max
fa = lambda d: d - target_dt if d >= target_dt else datetime.timedelta.max
fnone = lambda d: target_dt - d if d < target_dt else d - target_dt
if before_target is None:
return min(date_list, key=fnone).date()
if before_target:
return min(date_list, key=fb).date()
else:
return min(date_list, key=fa).date()
[docs]def closest_ds_partition(
table, ds, before=True, schema="default",
metastore_conn_id='metastore_default'):
"""
This function finds the date in a list closest to the target date.
An optional parameter can be given to get the closest before or after.
:param table: A hive table name
:type table: str
:param ds: A datestamp ``%Y-%m-%d`` e.g. ``yyyy-mm-dd``
:type ds: list[datetime.date]
:param before: closest before (True), after (False) or either side of ds
:type before: bool or None
:returns: The closest date
:rtype: str or None
>>> tbl = 'airflow.static_babynames_partitioned'
>>> closest_ds_partition(tbl, '2015-01-02')
'2015-01-01'
"""
from airflow.hooks.hive_hooks import HiveMetastoreHook
if '.' in table:
schema, table = table.split('.')
hh = HiveMetastoreHook(metastore_conn_id=metastore_conn_id)
partitions = hh.get_partitions(schema=schema, table_name=table)
if not partitions:
return None
part_vals = [list(p.values())[0] for p in partitions]
if ds in part_vals:
return ds
else:
parts = [datetime.datetime.strptime(pv, '%Y-%m-%d')
for pv in part_vals]
target_dt = datetime.datetime.strptime(ds, '%Y-%m-%d')
closest_ds = _closest_date(target_dt, parts, before_target=before)
return closest_ds.isoformat()