On some database types, combining locking reads with aggregate functions
is not allowed, and MediaWiki detects such cases and logs a deprecation
warning (on all database types), so we don’t really want people to use
this even if the target database type happens to support it. Add a
warning to the documentation.
Change-Id: Ib6fd2148aeb0c94c0a13b33aec08e3308c740b01
* is applied to a result set after OFFSET.
*
* - FOR UPDATE: Boolean: lock the returned rows so that they can't be
- * changed until the next COMMIT.
+ * changed until the next COMMIT. Cannot be used with aggregate functions
+ * (COUNT, MAX, etc., but also DISTINCT).
*
* - DISTINCT: Boolean: return only unique result rows.
*