1. A system comprising: one or more processors; one or more computer-readable storage mediums containing instructions configured to cause the one or more processors to perform operations including: analyzing, in a single-read pass, a distribution of time-stamped unstructured data to identify a plurality of potential time series data hierarchies for structuring the unstructured data, wherein a potential time series data hierarchy is a framework for structuring the unstructured data using multiple time series; performing, in the single-read pass through the unstructured data, an analysis of the potential time series data hierarchies, wherein performing the analysis of the potential time series data hierarchies includes determining an optimal time series frequency and a data sufficiency metric for each of the potential time series data hierarchies; selecting, in the single-read pass through the unstructured data, one of the potential time series data hierarchies based on a comparison of the data sufficiency metrics; deriving, in the single-read pass through the unstructured data, multiple structured time series from the unstructured data according to the selected time series data hierarchy, wherein a derived time series includes observations at intervals of time spaced in a manner commensurate with the optimal time series frequency determined for the selected time series data hierarchy; and generating a time series forecast corresponding to at least one of the derived time series.