Transportable Tablespace Migrations with Expdp/Impdp    Send article as PDF   

In the old days of exp/imp doing a Transportable Tablespace export/import was relatively simple – unless you had Spatial data, in which case, it wasn’t. Then we got hold of expdp/impdp and it became “different“. It now seems that in order to do a Transportable Tablespace import with impdp, you don’t tell it to do one! Confused?

In the old days, you told both exp and imp which tablespaces you were transporting using the TRANSPORT_TABLESPACE and TABLESPACES parameters to exp, and the same with imp. Life was good and symmetrical back then!

With expdp, we have a similar parameter whereby we simply list the tablespaces we wish to transport in the TRANSPORT_TABLESPACES (note, plural) parameter.

You would think that a similar arrangement would exist with impdp wouldn’t you? Well it does. Sort of!

There is indeed a TRANSPORT_TABLESPACES (note, plural) parameter on impdp but, if you use it, you must also specify a database link name in the NETWORK_LINK parameter and that link must exist in the importing database and it must point back to the exporting database. There is no intermediate dump file, the metadata is unloaded from the source database over the database link. Smart?

Not quite. Imagine that you have a production database to export and then import into a QA database, for example. However, the two are on separate networks, and there’s an air gap between the two. You cannot set up a database link from the QA database to the Production one to get at the metadata for the Transportable Tablespace import.

If you try, without a database link in place and working, impdp will simply barf.

The solution is hidden away in a note attached to the TRANSPORT_TABLESPACES in the Utilities manual, impdp section, in the locked filing cabinet, in the office in the basement, behind the leopard guarding the stairs, down the dark corridor etc. (Douglas Adams.)

What you have to do is not use the TRANSPORT_TABLESPACES parameter as you would imagine, instead, you list the transported data files using the TRANSPORT_DATAFILES and avoid the TRANSPORT_TABLESPACES like the plague! Goodby symmetry, it was nice of you to drop in!

So far, so bad. However, my original problem with deferred segment creation still exists even with impdp instead of imp.

$ impdp directory=... dumpfile=... logfile=... transport_datafiles=file1.dbf ...
ORA-39083: Object type TABLE:"NORMAN"."TEST_TABLE" failed to create with error:
ORA-01647: tablespace 'TEST_TABLESPACE' is read-only, cannot allocate space in it

Of course it’s read-only, it doesn’t exist in the database because impdp is supposed to create it, load up the metadata and connect that with the data files etc. Then I have to login and make the tablespace read write when I’m done.


Leave a Reply