Title --- PLP: Page Latch-free Shared-everything OLTP

Authors --- Ippokratis Pandis, Pinar Tozun, Ryan Johnson, Anastasia Ailamaki

Presented by: Ashwin Kayyoor.

Abstract --- Scaling the performance of shared-everything transaction
processing systems to highly-parallel multicore hardware re-
mains a challenge for database system designers. Recent
proposals alleviate locking and logging bottlenecks in the
system, leaving page latching as the next potential problem.
To tackle the page latching problem, we propose physiologi-
cal partitioning (PLP). The PLP design applies logical-only
partitioning, maintaining the desired properties of shared-
everything designs, and introduces a multi-rooted B+Tree
index structure (MRBTree) which enables the partitioning
of the accesses at the physical page level. Logical partition-
ing and MRBTrees together ensure that all accesses to a
given index page come from a single thread and, hence, can
be entirely latch-free; an extended design makes heap page
accesses thread-private as well. Eliminating page latching
allows us to simplify key code paths in the system such as
B+Tree operations leading to more efficient and maintain-
able code. Profiling a prototype PLP system running on
different multicore machines shows that it acquires 85% and
68% fewer contentious critical sections, respectively, than an
optimized conventional design and one based on logical-only
partitioning. PLP also improves performance up to 40% and
18%, respectively, over the existing systems.