add idempotent mode

CHANGES.md

@@ -1,5 +1,8 @@
 # django-pg-zero-downtime-migrations changelog
 
+## 0.15
+ - added idempotent mode and `ZERO_DOWNTIME_MIGRATIONS_IDEMPOTENT_SQL` setting
+
 ## 0.14
  - fixed deferred sql errors
  - added django 5.0 support

README.md

@@ -106,8 +106,23 @@ Define way to apply deferred sql, default `True`:
  ZERO_DOWNTIME_DEFERRED_SQL = True
 
 Allowed values:
-- `True` - run deferred sql similar to default django way.
-- `False` - run deferred sql as soon as possible.
+- `True` - run deferred sql similar to default django way
+- `False` - run deferred sql as soon as possible
+
+#### ZERO_DOWNTIME_MIGRATIONS_IDEMPOTENT_SQL
+
+Define idempotent mode, default `False`:
+
+ ZERO_DOWNTIME_MIGRATIONS_IDEMPOTENT_SQL = False
+
+Allowed values:
+- `True` - skip already applied sql migrations
+- `False` - standard non atomic django behaviour
+
+As this backend doesn't use transactions for migrations any failed migration can be cause of stopped process in intermediate state.
+To avoid manual schema manipulation idempotent mode allows to rerun failed migration after fixed issue (eg. data issue or long running CRUD queries).
+
+> _NOTE:_ idempotent mode checks rely only on name and index and constraint valid state, so it can ignore name collisions and recommended do not use it for CI checks.
 
 #### PgBouncer and timeouts
 

tests/apps/idempotency_add_check_app/migrations/0001_initial.py

@@ -0,0 +1,42 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+ initial = True
+
+ dependencies = []
+
+ operations = [
+ migrations.CreateModel(
+ name="RelatedTestTable",
+ fields=[
+ (
+ "id",
+ models.AutoField(
+ auto_created=True,
+ primary_key=True,
+ serialize=False,
+ verbose_name="ID",
+ ),
+ ),
+ ("test_field_int", models.IntegerField(null=True)),
+ ],
+ ),
+ migrations.CreateModel(
+ name="TestTable",
+ fields=[
+ (
+ "id",
+ models.AutoField(
+ auto_created=True,
+ primary_key=True,
+ serialize=False,
+ verbose_name="ID",
+ ),
+ ),
+ ("test_field_int", models.IntegerField()),
+ ("test_field_str", models.CharField(max_length=10)),
+ ],
+ ),
+ ]

tests/apps/idempotency_add_check_app/migrations/0002_relatedtesttable_idempotency_add_check_app_relatedtesttable_check.py

@@ -0,0 +1,20 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+ atomic = False
+
+ dependencies = [
+ ("idempotency_add_check_app", "0001_initial"),
+ ]
+
+ operations = [
+ migrations.AddConstraint(
+ model_name="relatedtesttable",
+ constraint=models.CheckConstraint(
+ check=models.Q(("test_field_int__gt", 0)),
+ name="idempotency_add_check_app_relatedtesttable_check",
+ ),
+ ),
+ ]

tests/apps/idempotency_add_check_app/models.py

@@ -0,0 +1,18 @@
+from django.db import models
+
+
+class TestTable(models.Model):
+ test_field_int = models.IntegerField()
+ test_field_str = models.CharField(max_length=10)
+
+
+class RelatedTestTable(models.Model):
+ test_field_int = models.IntegerField(null=True)
+
+ class Meta:
+ constraints = [
+ models.CheckConstraint(
+ check=models.Q(test_field_int__gt=0),
+ name="idempotency_add_check_app_relatedtesttable_check",
+ )
+ ]

tests/apps/idempotency_add_column_app/migrations/0001_initial.py

@@ -0,0 +1,42 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+ initial = True
+
+ dependencies = []
+
+ operations = [
+ migrations.CreateModel(
+ name="RelatedTestTable",
+ fields=[
+ (
+ "id",
+ models.AutoField(
+ auto_created=True,
+ primary_key=True,
+ serialize=False,
+ verbose_name="ID",
+ ),
+ ),
+ ("test_field_int", models.IntegerField(null=True)),
+ ],
+ ),
+ migrations.CreateModel(
+ name="TestTable",
+ fields=[
+ (
+ "id",
+ models.AutoField(
+ auto_created=True,
+ primary_key=True,
+ serialize=False,
+ verbose_name="ID",
+ ),
+ ),
+ ("test_field_int", models.IntegerField()),
+ ("test_field_str", models.CharField(max_length=10)),
+ ],
+ ),
+ ]

tests/apps/idempotency_add_column_app/migrations/0002_relatedtesttable_test_model.py

@@ -0,0 +1,25 @@
+# Generated by Django 5.0 on 2024-04-22 17:47
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+ atomic = False
+
+ dependencies = [
+ ("idempotency_add_column_app", "0001_initial"),
+ ]
+
+ operations = [
+ migrations.AddField(
+ model_name="relatedtesttable",
+ name="test_model",
+ field=models.OneToOneField(
+ null=True,
+ on_delete=django.db.models.deletion.CASCADE,
+ to="idempotency_add_column_app.testtable",
+ ),
+ ),
+ ]

tests/apps/idempotency_add_column_app/models.py

@@ -0,0 +1,11 @@
+from django.db import models
+
+
+class TestTable(models.Model):
+ test_field_int = models.IntegerField()
+ test_field_str = models.CharField(max_length=10)
+
+
+class RelatedTestTable(models.Model):
+ test_field_int = models.IntegerField(null=True)
+ test_model = models.OneToOneField(TestTable, null=True, on_delete=models.CASCADE)

tests/apps/idempotency_add_foreign_key_app/migrations/0001_initial.py

@@ -0,0 +1,42 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+ initial = True
+
+ dependencies = []
+
+ operations = [
+ migrations.CreateModel(
+ name="RelatedTestTable",
+ fields=[
+ (
+ "id",
+ models.AutoField(
+ auto_created=True,
+ primary_key=True,
+ serialize=False,
+ verbose_name="ID",
+ ),
+ ),
+ ("test_field_int", models.IntegerField(null=True)),
+ ],
+ ),
+ migrations.CreateModel(
+ name="TestTable",
+ fields=[
+ (
+ "id",
+ models.AutoField(
+ auto_created=True,
+ primary_key=True,
+ serialize=False,
+ verbose_name="ID",
+ ),
+ ),
+ ("test_field_int", models.IntegerField()),
+ ("test_field_str", models.CharField(max_length=10)),
+ ],
+ ),
+ ]

tests/apps/idempotency_add_foreign_key_app/migrations/0002_alter_relatedtesttable_test_field_int.py

@@ -0,0 +1,26 @@
+# Generated by Django 5.0 on 2024-04-23 10:59
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+ atomic = False
+
+ dependencies = [
+ ("idempotency_add_foreign_key_app", "0001_initial"),
+ ]
+
+ operations = [
+ migrations.AlterField(
+ model_name="relatedtesttable",
+ name="test_field_int",
+ field=models.OneToOneField(
+ db_column="test_field_int",
+ null=True,
+ on_delete=django.db.models.deletion.CASCADE,
+ to="idempotency_add_foreign_key_app.testtable",
+ ),
+ ),
+ ]

tests/apps/idempotency_add_foreign_key_app/models.py

@@ -0,0 +1,15 @@
+from django.db import models
+
+
+class TestTable(models.Model):
+ test_field_int = models.IntegerField()
+ test_field_str = models.CharField(max_length=10)
+
+
+class RelatedTestTable(models.Model):
+ test_field_int = models.OneToOneField(
+ TestTable,
+ null=True,
+ on_delete=models.CASCADE,
+ db_column="test_field_int",
+ )

tests/apps/idempotency_add_primary_key_app/migrations/0001_initial.py

@@ -0,0 +1,42 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+ initial = True
+
+ dependencies = []
+
+ operations = [
+ migrations.CreateModel(
+ name="RelatedTestTable",
+ fields=[
+ (
+ "id",
+ models.AutoField(
+ auto_created=True,
+ primary_key=True,
+ serialize=False,
+ verbose_name="ID",
+ ),
+ ),
+ ("test_field_int", models.IntegerField()),
+ ],
+ ),
+ migrations.CreateModel(
+ name="TestTable",
+ fields=[
+ (
+ "id",
+ models.AutoField(
+ auto_created=True,
+ primary_key=True,
+ serialize=False,
+ verbose_name="ID",
+ ),
+ ),
+ ("test_field_int", models.IntegerField()),
+ ("test_field_str", models.CharField(max_length=10)),
+ ],
+ ),
+ ]

tests/apps/idempotency_add_primary_key_app/migrations/0002_remove_relatedtesttable_id_and_more.py

@@ -0,0 +1,22 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+ atomic = False
+
+ dependencies = [
+ ("idempotency_add_primary_key_app", "0001_initial"),
+ ]
+
+ operations = [
+ migrations.RemoveField(
+ model_name="relatedtesttable",
+ name="id",
+ ),
+ migrations.AlterField(
+ model_name="relatedtesttable",
+ name="test_field_int",
+ field=models.IntegerField(primary_key=True, serialize=False),
+ ),
+ ]

tests/apps/idempotency_add_primary_key_app/models.py

@@ -0,0 +1,10 @@
+from django.db import models
+
+
+class TestTable(models.Model):
+ test_field_int = models.IntegerField()
+ test_field_str = models.CharField(max_length=10)
+
+
+class RelatedTestTable(models.Model):
+ test_field_int = models.IntegerField(primary_key=True)