1. A method of propagating a plurality of changes made to application software that uses a first relational database, the method comprising: a first computer receiving an identification of a first table in the first relational database; wherein first data in the first table in the first relational database is used in the application software; the first computer checking if the first table is a primary object, by using a first data structure comprising a first plurality of predetermined types indicative of primary objects; the first computer extracting first metadata describing the first table from a first data dictionary; wherein the first data dictionary is comprised in the first relational database; the first computer using the first metadata to prepare a first description of properties of the first table, the first description being expressed in a text based markup language; the first computer checking the first relational database, to see if said first table has associated thereto a first secondary object of any type identified by a second data structure comprising a second plurality of predetermined types indicative of secondary objects; in response to finding said first secondary object associated with said first table during said checking the first relational database, the first computer extracting from the first data dictionary second metadata describing the first secondary object in the first relational database, and the first computer preparing a second description of properties of the first secondary object; a second computer receiving at least: said first description of said first metadata, said second description of said second metadata, and the plurality of changes to the application software; wherein at least one change in the plurality of changes is related to use of first data in said first table; the second computer identifying a structural difference between said first table in said first relational database and a second table in a second relational database in said second computer, by comparing at least said first metadata of said first table to corresponding second metadata of said second table in a second data dictionary of the second relational-database; wherein the second data in the second table is used by the second computer in executing a copy of the application software; the second computer structurally changing the second table depending at least partially on an outcome of said comparing, to generate a changed second table; and the second computer executing a changed version of the application software, obtained by the second computer changing said copy by applying said plurality of changes, to use the changed second table.