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How Extensibility Works Postgres is extensible because its operation is catalog-driven . However , an operator is not merely syntactic sugar , because it carries additional information that helps the query planner optimize queries that use the operator . GROUP BY will condense into a single row all rows that share the same values for the grouped columns ; aggregates return values derived from all rows that make up the group . Wheeler is involved in the transmission line design teams for the new Aquarium / World of Coke site in Atlanta , the award winning Atlantic Station Project , and the Perry Homes / West Highlands revitalization effort . Remember that all database access actually occurs through the database backend , so that any location specified must be accessible by the backend . David Lee , project engineer with The Ballard Group Inc. in Lakewood , Colorado , designs mechanical systems for buildings to provide comfortable and safe environments for the occupants . But it cannot do the same thing on UPDATE or DELETE , because there is no real data in the view relation that could be scanned and thus the trigger would never get called . Connections from a client to the database server are , by default , allowed only via a local Unix socket , not via TCP / IP sockets . For the things that can be implemented by both , it depends on the usage of the database , which is the best . International Rescue Committee - They have been very much involved with relief for Tsunami victims but they have had an extensive involvement in Summatra for some time because of the refugee problems . As the message suggests , the postmaster refused the connection request because it found no authorizing entry in its pg_hba.conf configuration file . Drafting or computer applications or similar technical courses are also recommended for the potential engineering technician .