Fixed #21039 -- Added AddIndexConcurrently/RemoveIndexConcurrently operations for PostgreSQL.

Thanks to Simon Charettes for review.

Co-Authored-By: Daniel Tao <daniel.tao@gmail.com>

1 files changed, 60 insertions, 0 deletions

diff --git a/django/contrib/postgres/operations.py b/django/contrib/postgres/operations.py
index 95e7edcdea..9e417725ec 100644
--- a/django/contrib/postgres/operations.py
+++ b/django/contrib/postgres/operations.py
@@ -1,7 +1,9 @@
 from django.contrib.postgres.signals import (
     get_citext_oids, get_hstore_oids, register_type_handlers,
 )
+from django.db.migrations import AddIndex, RemoveIndex
 from django.db.migrations.operations.base import Operation
+from django.db.utils import NotSupportedError
 
 
 class CreateExtension(Operation):
@@ -75,3 +77,61 @@ class UnaccentExtension(CreateExtension):
 
     def __init__(self):
         self.name = 'unaccent'
+
+
+class NotInTransactionMixin:
+    def _ensure_not_in_transaction(self, schema_editor):
+        if schema_editor.connection.in_atomic_block:
+            raise NotSupportedError(
+                'The %s operation cannot be executed inside a transaction '
+                '(set atomic = False on the migration).'
+                % self.__class__.__name__
+            )
+
+
+class AddIndexConcurrently(NotInTransactionMixin, AddIndex):
+    """Create an index using PostgreSQL's CREATE INDEX CONCURRENTLY syntax."""
+    atomic = False
+
+    def describe(self):
+        return 'Concurrently create index %s on field(s) %s of model %s' % (
+            self.index.name,
+            ', '.join(self.index.fields),
+            self.model_name,
+        )
+
+    def database_forwards(self, app_label, schema_editor, from_state, to_state):
+        self._ensure_not_in_transaction(schema_editor)
+        model = to_state.apps.get_model(app_label, self.model_name)
+        if self.allow_migrate_model(schema_editor.connection.alias, model):
+            schema_editor.add_index(model, self.index, concurrently=True)
+
+    def database_backwards(self, app_label, schema_editor, from_state, to_state):
+        self._ensure_not_in_transaction(schema_editor)
+        model = from_state.apps.get_model(app_label, self.model_name)
+        if self.allow_migrate_model(schema_editor.connection.alias, model):
+            schema_editor.remove_index(model, self.index, concurrently=True)
+
+
+class RemoveIndexConcurrently(NotInTransactionMixin, RemoveIndex):
+    """Remove an index using PostgreSQL's DROP INDEX CONCURRENTLY syntax."""
+    atomic = False
+
+    def describe(self):
+        return 'Concurrently remove index %s from %s' % (self.name, self.model_name)
+
+    def database_forwards(self, app_label, schema_editor, from_state, to_state):
+        self._ensure_not_in_transaction(schema_editor)
+        model = from_state.apps.get_model(app_label, self.model_name)
+        if self.allow_migrate_model(schema_editor.connection.alias, model):
+            from_model_state = from_state.models[app_label, self.model_name_lower]
+            index = from_model_state.get_index_by_name(self.name)
+            schema_editor.remove_index(model, index, concurrently=True)
+
+    def database_backwards(self, app_label, schema_editor, from_state, to_state):
+        self._ensure_not_in_transaction(schema_editor)
+        model = to_state.apps.get_model(app_label, self.model_name)
+        if self.allow_migrate_model(schema_editor.connection.alias, model):
+            to_model_state = to_state.models[app_label, self.model_name_lower]
+            index = to_model_state.get_index_by_name(self.name)
+            schema_editor.add_index(model, index, concurrently=True)