The new implementation of SELECT FOR UPDATE adds a locking lookup join on top of the SELECT plan. For very simple SFU statements this locking lookup join can add measurable overhead over the old implementation of SFU, which pushed locking down to the initial row fetch.
We should try to push locking down and eliminate the lookup join for at least the simplest queries, where the difference will stand out more.
Jira issue: CRDB-33568
The new implementation of SELECT FOR UPDATE adds a locking lookup join on top of the SELECT plan. For very simple SFU statements this locking lookup join can add measurable overhead over the old implementation of SFU, which pushed locking down to the initial row fetch.
We should try to push locking down and eliminate the lookup join for at least the simplest queries, where the difference will stand out more.
Jira issue: CRDB-33568