Extended use of Standard Chunk sizes
In 10gR2, the server has been enhanced to further leverage standard chunk
allocation sizes. This additional improvement reduces the number of problems
arising from memory fragmentation.
Mutexes
To improve cursor execution and also hard parsing, a new memory serialization
mechanism has been created in 10gR2. For certain shared-cursor related
operations, mutexes are used as a replacement for library cache latches and
librarycache pins. Using mutexes is faster, uses less CPU and also allows
significantly improved concurrency over the existing latch mechanism. The use of
mutexes for cursor pins can be enabled by setting the init.ora parameter _use_kks_mutex
toTRUE.
V$SGASTAT
As mentioned earlier, V$SGASTAT has been enhanced to display a finer granularity
of memory to component allocation within the shared pool. This allows faster
diagnosis of memory usage (in prior releases many smaller allocations were
grouped under the ‘miscellaneous’ heading).
V$SQLSTAT
A new view, V$SQLSTAT has
been introduced which contains SQL related statistics (such as CPU time, elapsed
time, sharable memory). This view is very cheap to query even on
high-concurrency systems, as it does not require librarycache latch use. It
contains the most frequently used SQL statistics in the V$SQL family of views.
V$OPEN_CURSOR
This implementation of this view has also been enhanced to be latchless, making
it inexpensive to query.
V$SQLAREA
The V$SQLAREA view has been improved in 10gR2; the view optimizes the
aggregation of the SQL statements while generating the view data.
