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Speed up DO NOTHING, 3.58 times faster now
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5 files changed

+113
-48
lines changed

5 files changed

+113
-48
lines changed

‎psqlextra/compiler.py‎

Lines changed: 52 additions & 33 deletions
Original file line numberDiff line numberDiff line change
@@ -70,50 +70,69 @@ def _rewrite_insert(self, sql, return_id=False):
7070
to include the ON CONFLICT clause.
7171
"""
7272

73+
returning = 'id' if return_id else '*'
74+
75+
if self.query.conflict_action.value == 'UPDATE':
76+
return self._rewrite_insert_update(sql, returning)
77+
elif self.query.conflict_action.value == 'NOTHING':
78+
return self._rewrite_insert_nothing(sql, returning)
79+
80+
raise SuspiciousOperation((
81+
'%s is not a valid conflict action, specify '
82+
'ConflictAction.UPDATE or ConflictAction.NOTHING.'
83+
) % str(self.query.conflict_action))
84+
85+
def _rewrite_insert_update(self, sql, returning):
86+
qn = self.connection.ops.quote_name
87+
88+
update_columns = ', '.join([
89+
'{0} = EXCLUDED.{0}'.format(qn(field.column))
90+
for field in self.query.update_fields
91+
])
92+
7393
# build the conflict target, the columns to watch
74-
# for conflict basically
94+
# for conflicts
7595
conflict_target = self._build_conflict_target()
7696

77-
# form the new sql query that does the insert
78-
new_sql = (
79-
'{insert} ON CONFLICT ({conflict_target}) DO {conflict_action}'
97+
return (
98+
'{insert} ON CONFLICT ({conflict_target}) DO UPDATE'
99+
' SET {update_columns} RETURNING {returning}'
80100
).format(
81101
insert=sql,
82102
conflict_target=conflict_target,
83-
conflict_action=self._build_conflict_action(return_id)
103+
update_columns=update_columns,
104+
returning=returning
84105
)
85106

86-
return new_sql
87-
88-
def _build_conflict_action(self, return_id=False):
89-
"""Builds the `conflict_action` for the DO clause."""
90-
91-
returning = 'id' if return_id else '*'
92-
107+
def _rewrite_insert_nothing(self, sql, returning):
93108
qn = self.connection.ops.quote_name
94109

95-
# construct a list of columns to update when there's a conflict
96-
if self.query.conflict_action.value == 'UPDATE':
97-
update_columns = ', '.join([
98-
'{0} = EXCLUDED.{0}'.format(qn(field.column))
99-
for field in self.query.update_fields
100-
])
101-
102-
return (
103-
'UPDATE SET {update_columns} RETURNING {returning}'
104-
).format(
105-
update_columns=update_columns,
106-
returning=returning
107-
)
108-
elif self.query.conflict_action.value == 'NOTHING':
109-
return (
110-
'NOTHING RETURNING {returning}'
111-
).format(returning=returning)
110+
# build the conflict target, the columns to watch
111+
# for conflicts
112+
conflict_target = self._build_conflict_target()
112113

113-
raise SuspiciousOperation((
114-
'%s is not a valid conflict action, specify '
115-
'ConflictAction.UPDATE or ConflictAction.NOTHING.'
116-
) % str(self.query.conflict_action))
114+
select_columns = ', '.join([
115+
'{0} = \'{1}\''.format(qn(column), getattr(self.query.objs[0], column))
116+
for column in self.query.conflict_target
117+
])
118+
119+
# this looks complicated, and it is, but it is for a reason... a normal
120+
# ON CONFLICT DO NOTHING doesn't return anything if the row already exists
121+
# so we do DO UPDATE instead that never executes to lock the row, and then
122+
# select from the table in case we're dealing with an existing row..
123+
return (
124+
'WITH insdata AS ('
125+
'{insert} ON CONFLICT ({conflict_target}) DO UPDATE'
126+
' SET id = NULL WHERE FALSE RETURNING {returning})'
127+
' SELECT * FROM insdata UNION ALL'
128+
' SELECT {returning} FROM {table} WHERE {select_columns} LIMIT 1;'
129+
).format(
130+
insert=sql,
131+
conflict_target=conflict_target,
132+
returning=returning,
133+
table=self.query.objs[0]._meta.db_table,
134+
select_columns=select_columns
135+
)
117136

118137
def _build_conflict_target(self):
119138
"""Builds the `conflict_target` for the ON CONFLICT

‎psqlextra/manager.py‎

Lines changed: 0 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -106,7 +106,6 @@ def insert_and_get(self, **fields):
106106
"""
107107

108108
if not self.conflict_target and not self.conflict_action:
109-
print('oh fuck');
110109
# no special action required, use the standard Django create(..)
111110
return super().create(**fields)
112111

@@ -115,16 +114,6 @@ def insert_and_get(self, **fields):
115114

116115
columns = rows[0]
117116

118-
# it could happen that in the case of ConflictAction.NOTHING, the
119-
# row already existed, and in that case, we have to do an extra SELECT
120-
if not columns:
121-
select_fields = {
122-
field: fields[field]
123-
for field in self.conflict_target
124-
}
125-
126-
return self.get(**select_fields)
127-
128117
# get a list of columns that are officially part of the model
129118
model_columns = [
130119
field.column

‎tests/benchmarks/test_insert_nothing.py‎

Lines changed: 57 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,57 @@
1+
import uuid
2+
3+
from django.db import models, transaction
4+
from django.db.utils import IntegrityError
5+
import pytest
6+
7+
from psqlextra.query import ConflictAction
8+
9+
from ..fake_model import get_fake_model
10+
11+
12+
def _traditional_insert(model, random_value):
13+
"""Performs a concurrency safe insert the
14+
traditional way."""
15+
16+
try:
17+
with transaction.atomic():
18+
return model.objects.create(field=random_value)
19+
except IntegrityError:
20+
return model.objects.filter(field=random_value).first()
21+
22+
23+
def _native_insert(model, random_value):
24+
"""Performs a concurrency safeinsert
25+
using the native PostgreSQL conflict resolution."""
26+
27+
return (
28+
model.objects
29+
.on_conflict(['field'], ConflictAction.NOTHING)
30+
.insert_and_get(field=random_value)
31+
)
32+
33+
34+
@pytest.mark.django_db()
35+
@pytest.mark.benchmark()
36+
def test_traditional_insert(benchmark):
37+
model = get_fake_model({
38+
'field': models.CharField(max_length=255, unique=True)
39+
})
40+
41+
random_value = str(uuid.uuid4())[:8]
42+
model.objects.create(field=random_value)
43+
44+
benchmark(_traditional_insert, model, random_value)
45+
46+
47+
@pytest.mark.django_db()
48+
@pytest.mark.benchmark()
49+
def test_native_insert(benchmark):
50+
model = get_fake_model({
51+
'field': models.CharField(max_length=255, unique=True)
52+
})
53+
54+
random_value = str(uuid.uuid4())[:8]
55+
model.objects.create(field=random_value)
56+
57+
benchmark(_native_insert, model, random_value)

‎tests/benchmarks/test_upsert.py‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -16,7 +16,8 @@ def _traditional_upsert(model, random_value):
1616
with transaction.atomic():
1717
return model.objects.create(field=random_value)
1818
except IntegrityError:
19-
return model.objects.filter(field=random_value).first()
19+
model.objects.update(field=random_value)
20+
return model.objects.get(field=random_value)
2021

2122

2223
def _native_upsert(model, random_value):

‎tests/test_on_conflict.py‎

Lines changed: 2 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -4,11 +4,10 @@
44
from .fake_model import get_fake_model
55
from psqlextra.query import ConflictAction
66

7+
78
class OnConflictTestCase(TestCase):
9+
810
def test_on_conflict(self):
911
model = get_fake_model({
1012
'myfield': models.CharField(max_length=255, unique=True)
1113
})
12-
13-
model.objects.on_conflict(['myfield'], ConflictAction.NOTHING).insert(myfield='cookie')
14-
model.objects.on_conflict(['myfield'], ConflictAction.NOTHING).insert(myfield='cookie')

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