There is a KNIME Labs plug-in named KNIME Datageneration (http://tech.knime.org/datageneration). It gives support to generate values from different distributions for existing rows to new columns:
Random Number Assigner: It supports uniform distribution
Gaussian Distributed Assigner: It supports Gaussian distribution
Beta Distributed Assigner: It supports beta distribution
Gamma Distributed Assigner: It supports gamma distribution
To generate rows with numeric content, the most obvious node is Data Generator. It generates data for clusters of normally distributed data for various dimensions with different cluster centers on the [0,1] interval. It also generates the cluster labels.
To generate empty rows for existing tables, the Add Empty Rows node gives options. You might also want to create a table specification before you add (new or additional) empty rows. This can be done using the Create Table Structure or the Table Creator nodes. Both are manual, but if you have a tab...