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Refs #33355 -- Constructed SQLite list aggregate types once.

This commit is contained in:
Adam Johnson 2021-12-10 08:14:16 +00:00 committed by Mariusz Felisiak
parent ec7554f1c2
commit 5f6a727a6a
1 changed files with 24 additions and 12 deletions
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36
django/db/backends/sqlite3/_functions.py
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@ -21,14 +21,6 @@ from django.utils.crypto import md5
from django.utils.duration import duration_microseconds from django.utils.duration import duration_microseconds
def list_aggregate(function):
"""
Return an aggregate class that accumulates values in a list and applies
the provided function to the data.
"""
return type('ListAggregate', (list,), {'finalize': function, 'step': list.append})
def register(connection): def register(connection):
create_deterministic_function = functools.partial( create_deterministic_function = functools.partial(
connection.create_function, connection.create_function,
@ -80,10 +72,10 @@ def register(connection):
# Don't use the built-in RANDOM() function because it returns a value # Don't use the built-in RANDOM() function because it returns a value
# in the range [-1 * 2^63, 2^63 - 1] instead of [0, 1). # in the range [-1 * 2^63, 2^63 - 1] instead of [0, 1).
connection.create_function('RAND', 0, random.random) connection.create_function('RAND', 0, random.random)
connection.create_aggregate('STDDEV_POP', 1, list_aggregate(statistics.pstdev)) connection.create_aggregate('STDDEV_POP', 1, StdDevPop)
connection.create_aggregate('STDDEV_SAMP', 1, list_aggregate(statistics.stdev)) connection.create_aggregate('STDDEV_SAMP', 1, StdDevSamp)
connection.create_aggregate('VAR_POP', 1, list_aggregate(statistics.pvariance)) connection.create_aggregate('VAR_POP', 1, VarPop)
connection.create_aggregate('VAR_SAMP', 1, list_aggregate(statistics.variance)) connection.create_aggregate('VAR_SAMP', 1, VarSamp)
def _sqlite_datetime_parse(dt, tzname=None, conn_tzname=None): def _sqlite_datetime_parse(dt, tzname=None, conn_tzname=None):
@ -467,3 +459,23 @@ def _sqlite_tan(x):
if x is None: if x is None:
return None return None
return tan(x) return tan(x)
class ListAggregate(list):
step = list.append
class StdDevPop(ListAggregate):
finalize = statistics.pstdev
class StdDevSamp(ListAggregate):
finalize = statistics.stdev
class VarPop(ListAggregate):
finalize = statistics.pvariance
class VarSamp(ListAggregate):
finalize = statistics.variance