Are expdp/impdp commands appropriate for daily schema sync?

Question

I've done following comands:

expdp system/password@localdb ^
schemas=SCH directory=dumps_dir dumpfile=SCH_%date%.dmp logfile=expdpSCH_%date%.log

It runs great, without errors. But when I use command:

impdp system/password@localdb ^
schemas=SCH directory=dumps_dir dumpfile=SCH_%date%.dmp logfile=impdpSCH_%date%.log

It gave me bunch of errors that tables, sequences and other stuff already exist. So I have a question, could I use such an approach or it's wrong and I should use something else?

Answer 1

Check the documentation for more information or type impdp help=y. There is a parameter (TABLE_EXISTS_ACTION) that defines if you want to overwrite existing objects or if you want to append.

TABLE_EXISTS_ACTION
Action to take if imported object already exists.
Valid keywords are: APPEND, REPLACE, [SKIP] and TRUNCATE.

Answer 2

No, that is not a possible way:

• Most of the non-table objects will already exist in your schema. You already get such error messages. The import will not overwrite it.
• You can configure how export should work if a table already exists but if there is a table that s referenced by another table then TRUNCATE and REPLACE will not work.
• Even if there is no foreign key reference to a table indexes will slow down the import dramatically
• A lot of other problems may occur (concerning triggers, partitions, references to other tables and maybe more)

So the only reasonable way to synchronize the schema using expdp/impdp is to drop the schema before you import.

If you don't want to drop the schema for some reason but replace the data of the tables a lot of additional operations are necessary.