VisualVM is a visual tool integrating several commandline JDK tools and lightweight profiling capabilities. Designed for both production and development time use, it further enhances the capability of monitoring and performance analysis for the Java SE platform.
Currently adding a column to a table with a non-NULL default results in
a rewrite of the table. For large tables this can be both expensive and
disruptive. This patch removes the need for the rewrite as long as the
default value is not volatile. The default expression is evaluated at
the time of the ALTER TABLE and the result stored in a new column
(attmissingval) in pg_attribute, and a new column (atthasmissing) is set
to true. Any existing row when fetched will be supplied with the
attmissingval. New rows will have the supplied value or the default and
so will never need the attmissingval.
M. Walker, H. Edwards, и C. Messom. GECCO '07: Proceedings of the 9th annual conference on
Genetic and evolutionary computation, 2, стр. 1760--1760. London, ACM Press, (7-11 July 2007)
R. Attar, V. Prabhu, M. Glueck, и A. Khan. Proceedings of the 2010 Spring Simulation
Multiconference, стр. 177:1--177:4. San Diego, CA, USA, Society for Computer Simulation International, (2010)
C. Bellettini, L. Capra, и M. Monga. Proceedings of the Workshop on Cooperative Support for Distributed Software Engineering Processes (CSSE'04), стр. 15--26. Linz, Austria, Austrian Computer Society, (сентября 2004)