This data is being served by a DODS Relational Database Server (DRDS), which is a somewhat unusual instance of a DODS server. All of the data served by the DRDS is stored in a relational database management system (DBMS). Queries from DODS clients are translated into SQL queries and sent to the underlying DBMS. The reuturned data is read by the DRDS and returned to the requesting client.
Because the DRDS is essentially a front end to a DBMS, the DDS's have a somewhat different meaning than in other DODS servers. Each DDS served by the a DRDS represents a table in the underlying DBMS. Since queries to the DBMS will return an unknown amount of data, each DDS basically must contain a representation of the tables contents defined as a DODS sequence. Because of this it rarely makes sense for a client to request the entire "dataset", as this request will return the entire contents of the table. When requesting data from a DRDS, it is best to get the dataset information (using the .info extension on the DODS URL) and then build a constrained request that just returns data that is actually desired. This doesn't mean that the entire table cannot be requested and sent, it is simply a caution that each dataset/DDS/table may in fact be very large.
unique(): This function gets used in the selection part of the DODS
constraint expression. It requires no parameters. Calling this funcion will
cause the return to contain only unique rows. This is useful for sifting
through numerous identical fields, for example station data that contains
instrument names. This is NOT very useful if you are trying to retrieve a
Regular Expressions: The typical DODS server supports the full range
regular expression syntax. THIS DODS server does not. Limited string matching is
available. The wild card characters '.' and '.*' may used. The '[...]' notation
for matching a range of characters may be used, but only to match a single
character to a range of possiblities.
location="Southern%20Ocean"However, if the DODS URL is formed with a space like this:
location="Southern Ocean"It will not be handled correctly by the DRDS.