Schema Naming Considerations

Schema Naming Considerations

Schema names follow identifier conventions, with significant considerations concerning the use of non-alphanumeric characters. A schema name should not be specified as a delimited identifier. Attempting to specify “USER” or any other SQL reserved word as a schema name results in an SQLCODE -312 error. The INFORMATION_SCHEMA schema name and the corresponding INFORMATION.SCHEMA package name are reserved in all namespaces. Users should not create tables/classes within this schema/package.

When you issue a create operation, such as CREATE TABLE, that specifies a schema that does not yet exist, InterSystems IRIS creates the new schema. InterSystems IRIS uses the schema name to generate a corresponding package name. Because the naming conventions for schemas and their corresponding packages differ, the user should be aware of name conversion considerations for non-alphanumeric characters. These name conversion considerations are not the same as for tables:

• Initial character:

  • % (percent): Specify % as the first character of a schema name denotes the corresponding package as a system package, and all of its classes as system classes. This usage requires appropriate privileges; otherwise, this usage issues an SQLCODE -400 error with the %msg indicating a <PROTECT> error.

  • _ (underscore): If the first character of a schema name is the underscore character, this character is replaced by a lowercase “u” in the corresponding package name. For example, the schema name _MySchema generates the package name uMySchema.

• Subsequent characters:

  • _ (underscore): If any character other than the first character of a schema name is the underscore character, this character is replaced by a period (.) in the corresponding package name. Because a period is the class delimiter, an underscore divides a schema into a package and a sub-package. Thus My_Schema generates the package My containing the package Schema (My.Schema).

  • @, #, $ characters: If a schema name contains any of these characters, these characters are stripped from the corresponding package name. If stripping these characters would produce a duplicate package name, the stripped package name is further modified: the final character of the stripped schema name is replaced by a sequential integer (beginning with 0) to produce a unique package name. Thus My@#$Schema generates package MySchema, and subsequently creating My#$Schema generates package MySchem0. The same rules apply to table name corresponding class names.