After an SQL statement is optimized, the Dispatcher sends the steps that make up that query, one at a time, to AMPs in the system. Steps are typically dispatched, and processes started, on all AMPs in the system. The Optimizer may decide that this query work can be accomplished by accessing only a single AMP in the configuration. This is called a single-AMP operation, or a single-AMP step.
Vantage uses single-AMP steps to localize work to the fewest resources necessary when beneficial to do so. This is frequently the case for tactical queries. Single-AMP work frees the other AMPs in the system to do other work, thereby increasing the potential for overall system throughput. This is diagrammed in the following figure:
Tactical queries are most efficient and most scalable when designed around single- or few-AMP operations. This is the most important way to increase throughput and preserve response times for short tactical queries. This is diagrammed in the following figure:
Single- or few-AMP queries scale well because they engage the same small level of database resources even when the system doubles or triples in size (see Scalability Considerations for Tactical Queries).