Using SIMD to aggregate billions of rows per second - QuestDB
SIMD instructions are specific CPU instruction sets for arithmetic calculations that use synthetic parallelisation. The parallelisation is synthetic because instead of spreading the work across CPU cores, SIMD performs vector operations on multiple items using a single CPU instruction. In practice, if you were to add 8 numbers together, SIMD does that in 1 operation instead of 8. We get compounded performance improvements by combining SIMD with actual parallelisation and spanning the work across CPUs.