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

Thanks to Simon Charettes for review.

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

2 files changed, 34 insertions, 0 deletions

diff --git a/docs/ref/contrib/postgres/operations.txt b/docs/ref/contrib/postgres/operations.txt
index c56693478f..1329ff1f9e 100644
--- a/docs/ref/contrib/postgres/operations.txt
+++ b/docs/ref/contrib/postgres/operations.txt
@@ -98,3 +98,33 @@ run the query ``CREATE EXTENSION IF NOT EXISTS hstore;``.
 .. class:: UnaccentExtension()
 
     Installs the ``unaccent`` extension.
+
+Index concurrent operations
+===========================
+
+.. versionadded:: 3.0
+
+PostgreSQL supports the ``CONCURRENTLY`` option to ``CREATE INDEX`` and
+``DROP INDEX`` statements to add and remove indexes without locking out writes.
+This option is useful for adding or removing an index in a live production
+database.
+
+.. class:: AddIndexConcurrently(model_name, index)
+
+    Like :class:`~django.db.migrations.operations.AddIndex`, but creates an
+    index with the ``CONCURRENTLY`` option. This has a few caveats to be aware
+    of when using this option, see `the PostgreSQL documentation of building
+    indexes concurrently <https://www.postgresql.org/docs/current/
+    sql-createindex.html#SQL-CREATEINDEX-CONCURRENTLY>`_.
+
+.. class:: RemoveIndexConcurrently(model_name, name)
+
+    Like :class:`~django.db.migrations.operations.RemoveIndex`, but removes the
+    index with the ``CONCURRENTLY`` option. This has a few caveats to be aware
+    of when using this option, see `the PostgreSQL documentation
+    <https://www.postgresql.org/docs/current/sql-dropindex.html>`_.
+
+.. note::
+
+    The ``CONCURRENTLY`` option is not supported inside a transaction (see
+    :ref:`non-atomic migration <non-atomic-migrations>`).
diff --git a/docs/releases/3.0.txt b/docs/releases/3.0.txt
index 5bb0691363..9489a38ca7 100644
--- a/docs/releases/3.0.txt
+++ b/docs/releases/3.0.txt
@@ -153,6 +153,10 @@ Minor features
 * The new :class:`~django.contrib.postgres.fields.RangeBoundary` expression
   represents the range boundaries.
 
+* The new :class:`~django.contrib.postgres.operations.AddIndexConcurrently`
+  and :class:`~django.contrib.postgres.operations.RemoveIndexConcurrently`
+  classes allow creating and dropping indexes ``CONCURRENTLY`` on PostgreSQL.
+
 :mod:`django.contrib.redirects`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~