Paradox is a relational database management system (RDBMS) owned by Corel. RDBMS systems store data in tables that can be joined together in queries to produces meaningful reports. The RDBMS model dominates modern database software with proponents including Oracle and Microsoft Access. Paradox stores its databases in files.
Database Files
- The main storage format of Paradox is the database file. The native file type has the .DB file extension. This replaced an earlier format, which had the .T file extension. A database file contains the structure of the database with descriptions of the tables, but does not include other objects in the database nor does it include any data. Table data goes in a file with a .PD file extension. Views on tables are stored in files with the .TV file extension and table filters are stored in files with the .DF file extension. Referential integrity is the rule set that prevents joins dropping records or multiplying records in a table. Paradox keeps referential integrity validation data in a file with the .VAL file extension. An .XGO file holds database metadata.
Indexing and Sorting
- Sort orders for data are held in a .SOM file. Indexing involves a wide range of files in Paradox. The index files divide into two categories of primary index and secondary indexes. There can only be one primary index on each table. The database's primary indexes are stored in a file with the .PX file extension. Secondary indexes use a large number of files. These all have the same format, but have different names. The secondary index files in Paradox have the following file extensions: .X01, .X02, .X03, .X04, .X05, .X06, .X07, .X08, .X09, .XG0, .XG1, .XG2, .XG3, .XG4, .XG5, .Y01, .Y02, .Y03, .Y04, .Y05, .Y06, .Y07, .Y08, .Y09, .YG0, .YG1, .YG2, .YG3 and .YG4.
Data Manipulation
- Apart from database objects, the Paradox package includes a system for writing scripts. Programming elements in Paradox include two different types of files. These are program files and program libraries. Libraries are stores of functions that can be accessed by programs. Libraries have two different file formats. These are the .LDL delivered library file format and the .LSL saved library format. Program scripts also have two different file extensions: .SC and .SDL.
Data Presentation
- Paradox includes a development environment for creating graphical user interface screens for data entry and database queries. These screens are called "forms" and occupy three different formats. A written program containing a form is called a “delivered form” and it is stored in a file with the .FLF file extension. After that program is compiled it goes into a .FSL file. The .RSL file extension denotes a saved form file.
Other Paradox Files
- Paradox includes a memo system and this occupies two file formats. An .MB file contains a memo holder and a memo file has the .DBQ file extension. Access control to the various files in a database is managed via a lock file with the .LCK file extension. One more file type found in the Paradox environment is an .LD file, which is a language driver.
