Larry yesterday did his keynote here at Oracle Open World introducing the “Oracle(R) Exadata Storage Server”. This morning I attended a session about the technical details behind the server. In principal the server works with 8 nodes running RAC on Oracle Enterprise Linux 5. For the storage management ASM is used and since 11.1.0.7 smart scan has been introduced. Smart scan has been designed for very big data sources used in queries, like in Data Warehouses, where tables from tera bytes are common. In principle the following is accomplished using smart scan:
With the traditional way of query, the following sequence of events can be identified:
- Client sends query to database server
- Database server will execute the query, to accomplish that the following has to be done:
- create execution plan
- ask for the different datasources to be retrieved from the storage
- apply the query criteria to reduce the datasources retrieved from the storage
- Database server sends the query result to the client
With Smart Scan in place, the following sequence of events can be identified:
- Client sends query to database server
- Database server will execute the query, to accomplish that the following has to be done:
- create execution plan
- apply the query criteria and sent Smart Scan constructed request
- Smart Scan identifies rows and columns direct on the storage
- process the much smaller datasources
- Database server sents the query results to the client
The big advantage of the Smart Scan principle is that there is less data transfer between physical disks and the database server. Currently the “Oracle(R) Exadata Storage Server” makes use of the infiniband protocol to talk to the underlaying disks, this gives together with a lot of hardware tuning an extreme performance with high end, big amounts of data transfer. Currently the machine is only usable for the Oracle database, so other things like software storage has to be done on a separate storage device.
To read further about the machine you can use the following link:
http://www.oracle.com/solutions/business_intelligence/database-machine.html
