MySQL Cluster Interconnects and Performance  The ndbd process
has a number of simple constructs which are used to access the
data in a MySQL Cluster. We have created a very simple benchmark
to check the performance of each of these and the effects which
various interconnects have on their performance.  There are four
access methods:  With benchmarks developed internally by MySQL
for testing simple and batched primary and unique key accesses,
we have found that using SCI sockets improves performance by
approximately 100% over TCP/IP, except in rare instances when
communication performance is not an issue. This can occur when
scan filters make up most of processing time or when very large
batches of primary key accesses are achieved. In that case, the
CPU processing in the ndbd processes becomes a fairly large part
of the overhead.  Using the SCI transporter instead of SCI
Sockets is only of interest in communicating between ndbd
processes. Using the SCI transporter is also only of interest if
a CPU can be dedi