CheckTable only checks the table headers of base global temporary tables and their instances; data rows of instances are not checked during level-one checking. For more information on level-one checking, see Level One Checks.
Stored procedures, UDFs, and UDMs, store their text and object code internally as special tables that are not normally accessible to users. Join index rows, and hash index rows are also stored internally as tables. CheckTable checks all of these tables, in addition to checking ordinary data tables.
Some checks are not done for unhashed tables, and certain join indexes and hash indexes.
CheckTable does not include the DBC.ALL table when accounting for tables checked because it is not considered a conventional table.
CheckTable does not check tables whose rollback has been canceled.
For foreign tables (tables created to analyze data in external object storage, such as AWS S3 data), CheckTable checks that table headers exist and that the Data Dictionary information for such tables is consistent. The COMPRESSCHECK and CHECKINVALIDSI options do not apply to foreign tables. For foreign tables, the check level is irrelevant; all levels perform the same checks.