Data Management
Detailed Information About the JGOFS Distributed Database Management System (DDMS)
Data Model - appearance to applications
The JGOFS data model is the critical part of the communications
protocol. It includes:
- Comments (text)
- Variable descriptions
- Name
- Dimensions for vectors/ matrices/ tensors [not implemented!]
- Attributes (e.g., units)
- Hierarchical structure
- Data
- End of data set indicator
The hierarchical structuring is an important way of organizing many
kinds of data. It groups the least rapidly changing variables (e.g.,
header data), then the next-most rapidly changing information,
etc. For example, a hydrographic section might look like
leg
year [lowest (0) level]
month
station
lat [level 1]
lon
date
press
temp
sal [level 2]
o2
sigth
A current meter mooring might have
mooring_id
lat
lon [level 0]
nominal_depth
start_time
end_time
time
u [level 1]
v
temp
Often one scans the lower level information first to pick out the
desired station or mooring and then retrieves the information only for
that subset of the data base.
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