Almost all data in R is a vector or is based upon vectors
(vectors themselves, matrices, data frames, lists, and so forth).
The elements of a vector in R have an explicit order, and
each element can be individually indexed. R's in-memory
processing relies on this order of elements for many computations,
e.g., computing quantiles and summaries for time series
objects.By design, query results in relational algebra are unordered.
Repeating the same query multiple times is not...
