  The next-generation astronomy archives will cover most of the universe at
fine resolution in many wavelengths. One of the first of these projects, the
Sloan Digital Sky Survey (SDSS) will create a 5-wavelength catalog over 10,000
square degrees of the sky. The 200 million objects in the multi-terabyte
database will have mostly numerical attributes, defining a space of 100+
dimensions. Points in this space have highly correlated distributions. The
archive will enable astronomers to explore the data interactively. Data access
will be aided by multidimensional spatial indices. The data will be partitioned
in many ways. Small tag objects consisting of the most popular attributes speed
up frequent searches. Splitting the data among multiple servers enables
parallel, scalable I/O. Hashing techniques allow efficient clustering and
pairwise comparison algorithms. Randomly sampled subsets allow debugging
otherwise large queries at the desktop. Central servers will operate a data
pump that supports sweeping searches that touch most of the data.
