An archive file collection is a list of archive files that can be logically unioned together as a single data source for open data manager (ODM) access. For example, ODM uses an archive file collection to provide access to data in multiple archive files, even if all files do not include a specific table or column or if the attributes of data in a column vary from file to file. ODM processes archive files in the order they are listed in the Archive File Collection Editor.
In an archive file collection, tables with matching creator IDs and names in separate archive files are unioned. To be processed, a table need not exist in every archive file in the collection. ODM is not case-sensitive and does not use DB Aliases; however, an archive file cannot include two tables with matching creator IDs and names but different DB aliases.
Matching tables are not required to have the same columns. The union includes all columns in the matching tables. Rows from a table that do not include a column found in another table use a default value such as NULL, a default date specified in the Archive File Collection Editor, or an appropriate data type (spaces, zero, etc.).
All columns with the same name that are in tables with matching creator IDs and names must have compatible attributes. If columns have different but compatible attributes, a compatible attribute is used for those columns. The column compatibility rules for the compare process apply to archive file collections.
For example, columns COLX DECIMAL(8,2) and COLX DECIMAL(10,0) become COLX DECIMAL(12,2).
If a compatible attribute cannot be found (for example, COLX INTEGER and COLX TIMESTAMP), the Archive File Collection Editor displays an error message.
Archive indexes for unioned tables can also be unioned. The following rules apply to unioned indexes:
If archive file security denies you access to a table or a column in table, no rows are retrieved from the table.