1. A computer-program product tangibly embodied in a non-transitory, machine-readable storage medium having instructions stored thereon, the instructions being executable to cause a grid-computing device to perform the following operations: accessing information while being operated in a grid-computing system that includes other grid-computing devices, wherein the information describes a hierarchical schema for assembling multiple time series of data in a distributed manner that includes assembling multiple time series at the grid-computing device and other time series at the other grid-computing devices, wherein the hierarchical schema associates each of the multiple time series with a particular level of the hierarchical schema and prescribes a structure of relationships between time series assigned to different levels of the hierarchical schema; assembling multiple time series associated with a lowest level of the hierarchical schema by inventorying a portion of a data set; assembling multiple time series associated with an intermediate level of the hierarchical schema by aggregating the time series associated with the lowest level based on the structure of nested relationships, wherein the intermediate level is above the lowest level; receiving multiple additional time series associated with the intermediate level and assembled by at least one of the other grid-computing devices; assembling a time series associated with a level of the hierarchical schema above the intermediate level by aggregating the assembled time series associated with the intermediate level and the multiple additional time series based on the structure of nested relationships; using volatile memory to store the time series associated with the level above the intermediate level; accessing the stored time series in memory; and generating a forecast by processing the accessed time series.