By Tanel Poder Thanks to IOUG team for giving me the IOUG Select
Journal Editor's Choice award (2011) for this article!!! As an
Oracle DBA, developer or performance analyst, you may have run
into what is termed "latch contention" at various points. So
what exactly is a "latch" and why do we have contention on this
"latch". In this article, we will take an in-depth look at
latches and how we determine and resolve such contention.
Whether you are a newbie or an experienced old-timer, we hope
this article will cast a little more light on this ill-
understood subject. I will put it very simply: Latch is a lock.
In fact, a latch is just another special type of lock in Oracle.
Oracle uses many different types of locks internally, for
example enqueue locks, library cache locks, library cache pins,
buffer cache pins, mutexes and latches and these different lock
types are useful for different purposes. Enqueue locks are
sophisticated, provide ordered queuing capabilities and are used
for cases where the locks are held