Collection

A collection is a named group of packages. It lets you keep multiple versions of the same programs without them colliding.

What is a collection

• A collection is a logical grouping of packages, identified by a collection-id of up to 18 characters.
• It is created implicitly the first time you BIND PACKAGE with that collection-id. No separate create step exists.
• Collections live in the DB2 catalog together with the packages they hold.
• A package is always addressed as collection-id.package-name, for example MYCOLL.PROG1.

Why collections are used

• Keep test and production versions of the same programs side by side, for example TESTCOLL and PRODCOLL.
• Promote code by binding into a new collection instead of overwriting the old one. Rollback is then just a PKLIST change.
• The plan's PKLIST lists collections in search order, so you control exactly which version runs.

Collection naming

• Follow standard DB2 naming rules: up to 18 characters, start with a letter, no embedded blanks.
• A common convention is environment plus application, for example PAYROLLT for test and PAYROLLP for production.
• Keep names in uppercase. Some tools and catalog queries are case-sensitive.

Example: binding into a collection

• The collection-id TESTCOLL is given right after BIND PACKAGE. The first bind creates the collection:
  
  DSN SYSTEM(DB2A) BIND PACKAGE (TESTCOLL) MEMBER (PAY01) LIB ('USERID.DBRMLIB') QUALIFIER (PAYOWN) END