Oracle Database 11g Oracle Real Application Clusters Handbook, 2nd Edition, 2nd Edition

Full Table Scans

Repetitive full table scans in Oracle RAC can impede performance and scalability as the private interconnect is used for transferring blocks, and that can eat into network bandwidth. This would cause a delay for other required and important blocks such as index blocks, undo blocks, header blocks, and any messages. The goal is to reduce interconnect traffic and bring down latency. With a lot of full table scans, interconnects could get overloaded, thereby flooding the private network.

Another very important factor to be considered with full table scans is an appropriate value for DB_FILE_MULTIBLOCK_READ_COUNT, also known as MBRC. Not only does this parameter have a charming influence on the optimizer to lean toward a full table ...