Mergeant manipulates two kinds of data: data provided by the DBMS and data provided by the user. The association of these two kinds of data enables Mergeant to perform some powerfull work. The data provided by the user completes the description of the database given by the DBMS (mainly more details about the structure).
When user defined data is given in place of DBMS data, it will override it (it will be given a higher priority).
As of version 0.6.x, Mergeant automatically knows about the following elements in a database (depending on the DBMS provider's degree of completeness and the DBMS' own features, see chapter ???):
users: all the declared users in a given database will be recognized.
tables and views: all the tables and views will appear to the user, with their respective owner, and the structure of each table or view (individual fields and their attributes, and primary keys).
sequences: will also appear (with their owner).
data types: all the data types that can be used in a database will appear. They fall in two cathegories: the "system" ones and the user-defined ones (if the DBMS supports that feature). For some data of a given datatype, the way the user is shown the data, and prompted to modify it will depend on plugins. Except for the most common data types such as date, char, etc. (which in any case can still be overrided), if there is no plugin, then the default methods will be used (data type treated as a string). See chapter ???
functions: all the functions in the database will appear, wether they are functions or aggregates, and "system" or user-defined (if the DBMS supports it). The number and data types of each of the arguments are checked when using those functions.
links as foreign keys: this is planned but not yet implemented.
The user is allowed to provide informations about:
links between fields of two tables (see chapter ???). The term relation will also be used in this manual to refer to a link.
comments on tables, or fields of tables: they can sometimes not be stored in the DBMS (either because there is no writing access or because the DBMS does not support it), so Mergeant allows the user to give comments on tables, fields, etc.
plugins usage: Mergeant can be extended using plugins; the way plugins are used is chosen by the user (see chapter ???)
the connection parameters: except the passwords, they will be saved.
all the information related to queries and the associated forms.
This information is the one which is stored in files for each connection to avoid entering it all each time a connection is reopened.