diff --git a/doc/src/sgml/ref/delete.sgml b/doc/src/sgml/ref/delete.sgml
index 1b81b4e7d74..0b6fa005123 100644
--- a/doc/src/sgml/ref/delete.sgml
+++ b/doc/src/sgml/ref/delete.sgml
@@ -260,12 +260,32 @@ DELETE FROM tasks WHERE status = 'DONE' RETURNING *;
-
+
Delete the row of tasks on which the cursor
c_tasks is currently positioned:
DELETE FROM tasks WHERE CURRENT OF c_tasks;
-
+
+
+
+
+ While there is no LIMIT clause
+ for DELETE, it is possible to get a similar effect
+ using the same method described in the
+ documentation of UPDATE:
+
+WITH delete_batch AS (
+ SELECT l.ctid FROM user_logs AS l
+ WHERE l.status = 'archived'
+ ORDER BY l.creation_date
+ FOR UPDATE
+ LIMIT 10000
+)
+DELETE FROM user_logs AS dl
+ USING delete_batch AS del
+ WHERE dl.ctid = del.ctid;
+
+
diff --git a/doc/src/sgml/ref/update.sgml b/doc/src/sgml/ref/update.sgml
index 2ab24b0523e..babb34fa511 100644
--- a/doc/src/sgml/ref/update.sgml
+++ b/doc/src/sgml/ref/update.sgml
@@ -441,7 +441,45 @@ COMMIT;
c_films is currently positioned:
UPDATE films SET kind = 'Dramatic' WHERE CURRENT OF c_films;
-
+
+
+
+
+ Updates affecting many rows can have negative effects on system
+ performance, such as table bloat, increased replica lag, and increased
+ lock contention. In such situations it can make sense to perform the
+ operation in smaller batches, possibly with a VACUUM
+ operation on the table between batches. While there is
+ no LIMIT clause for UPDATE, it is
+ possible to get a similar effect through the use of
+ a Common Table Expression and a
+ self-join. With the standard PostgreSQL
+ table access method, a self-join on the system
+ column ctid is very
+ efficient:
+
+WITH exceeded_max_retries AS (
+ SELECT w.ctid FROM work_item AS w
+ WHERE w.status = 'active' AND w.num_retries > 10
+ ORDER BY w.retry_timestamp
+ FOR UPDATE
+ LIMIT 5000
+)
+UPDATE work_item SET status = 'failed'
+ FROM exceeded_max_retries AS emr
+ WHERE work_item.ctid = emr.ctid;
+
+ This command will need to be repeated until no rows remain to be updated.
+ Use of an ORDER BY clause allows the command to
+ prioritize which rows will be updated; it can also prevent deadlock
+ with other update operations if they use the same ordering.
+ If lock contention is a concern, then SKIP LOCKED
+ can be added to the CTE to prevent multiple commands
+ from updating the same row. However, then a
+ final UPDATE without SKIP LOCKED
+ or LIMIT will be needed to ensure that no matching
+ rows were overlooked.
+