Smart Scan is probably the most important performance component in Exadata’s software offering in terms of delivering extreme performance. Smart Scan is a cell offload feature whose goal is to offload processing to storage cells instead of performing block I/O requests in the database tier. The goal of Smart Scan processing is to do all the “heavy lifting”, I/O-wise, in the storage cell and only send back data to the compute nodes that is actually needed and requested. This reduces interconnect traffic between the storage grid and database tier, reduces the clutter in the database buffer cache, improves query performance, and improves concurrency for multiple full-scan types of queries happening at once. With smart scan processing, row filtering, column filtering, some join processing, and other functions are performed in the Exadata cells.
KeywordsDirect Path Execution Plan Storage Cell Direct Read Cache Block
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