Errors can occur for many reasons when you import database objects, as described in this section. When these errors occur, import of the current database object is discontinued. Import then attempts to continue with the next database object in the export file.
If a database object to be imported already exists in the database, then an object creation error occurs. What happens next depends on the setting of the IGNORE parameter.
If IGNORE=n (the default), then the error is reported, and Import continues with the next database object. The current database object is not replaced. For tables, this behavior means that rows contained in the export file are not imported.
If IGNORE=y, then object creation errors are not reported. The database object is not replaced. If the object is a table, then rows are imported into it. Note that only object creation errors are ignored; all other errors (such as operating system, database, and SQL errors) are reported and processing may stop.
If sequence numbers need to be reset to the value in an export file as part of an import, then you should drop sequences. If a sequence is not dropped before the import, then it is not set to the value captured in the export file, because Import does not drop and re-create a sequence that already exists. If the sequence already exists, then the export file's CREATE SEQUENCE statement fails and the sequence is not imported.
Resource limitations can cause objects to be skipped. When you are importing tables, for example, resource errors can occur because of internal problems or when a resource such as memory has been exhausted.
If a resource error occurs while you are importing a row, then Import stops processing the current table and skips to the next table. If you have specified COMMIT=y, then Import commits the partial import of the current table. If not, then a rollback of the current table occurs before Import continues. See the description of "COMMIT".
Domain indexes can have associated application-specific metadata that is imported using anonymous PL/SQL blocks. These PL/SQL blocks are executed at import time, before the CREATE INDEX statement. If a PL/SQL block causes an error, then the associated index is not created because the metadata is considered an integral part of the index.