Depending on the query and the actual data, Vector can process data at more than 1.5 GB/s per CPU core. In order to achieve this data processing rate the CPU cores have to be fed at a rate fast enough to keep them busy. If data is compressed--which it is by default--then the cost of decompression is about 25% of the CPU core’s processing capacity.

Use the following formula to calculate the maximum required bandwidth:

Multiply this number by the number of cores in your system to calculate the total required disk throughput to drive the maximum bandwidth across all CPU cores.

Note that such a high I/O consumption requirement is typically found with relatively simple queries such as single-table scans with aggregations. For more complex queries (e.g. performing many joins against small memory-resident tables), the I/O consumption requirement may be significantly less.

Note also that the data compression ratio you achieve depends on the data types in your tables as well as the actual data. It is common to achieve 3-5x compression ratios, although both higher and lower compression ratios have been observed.

Maximum data processing throughput is achieved only if all cores are fully occupied. Also, relatively simple queries require more data throughput in contrast to computation-intensive queries. If you choose to not configure your system to achieve absolute maximum performance, then you should know that the system, if fully busy executing relatively simple queries, will likely become I/O-bound and not achieve maximum performance.