database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-08-28 18:48:04 +03:00
Code Activity

Doc: show how to get the equivalent of LIMIT for UPDATE/DELETE.

Browse Source 
Add examples showing use of a CTE and a self-join to perform
partial UPDATEs and DELETEs.

Corey Huinker, reviewed by Laurenz Albe

Discussion: https://postgr.es/m/CADkLM=caNEQsUwPWnfi2jR4ix99E0EJM_3jtcE-YjnEQC7Rssw@mail.gmail.com
This commit is contained in:
Tom Lane
2024-04-07 16:26:47 -04:00
parent 1973d9fb31
commit 2daeba6a4e
2 changed files with 61 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
doc/src/sgml/ref/delete.sgml
View File

@@ -260,12 +260,32 @@ DELETE FROM tasks WHERE status = 'DONE' RETURNING *;
</programlisting>
</para>
<para>
<para>
Delete the row of <structname>tasks</structname> on which the cursor
<literal>c_tasks</literal> is currently positioned:
<programlisting>
DELETE FROM tasks WHERE CURRENT OF c_tasks;
</programlisting></para>
</programlisting>
</para>
<para>
While there is no <literal>LIMIT</literal> clause
for <command>DELETE</command>, it is possible to get a similar effect
using the same method described in <link linkend="update-limit">the
documentation of <command>UPDATE</command></link>:
<programlisting>
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;
</programlisting>
</para>
</refsect1>
<refsect1>