How to transfer data using expdp and impdp commands?
I'm an Oracle noob, and my intention is to transfer all data and metadata from one schema to another schema within an Oracle database. I'm planning to use datapump's
impdpcommands. I have questions regarding this:
- Can I create a target schema without a user or should I create a user first (which creates a schema also)?
- Can I execute
impdpcommands using SYS (as sysdba) account? Is that a preferred method?
Does this statement take all the objects (data and metadata) from a schema and move these into a different schema?
expdp \"/ as sysdba\" schemas=<schemaname> directory=dumpdir dumpfile=<schemaname>.dmp logfile=expdp_<schemaname>.log
So is the target schema an exact copy of the source schema after
impdpwill create the user if it's not present yet, so you don't have to worry about it unless that's not what you want.
Do not run
sysdba, only do that if Oracle support requests it in specific circumstances. Use an ordinary user for that - one that has been granted the
dbarole for instance. (There are the
[IMPORT|EXPORT]_FULL_DATABASEprivileges specifically for this type of thing, you'll need to grant access to the Oracle directory object(s) too.)
A full schema export (metadata and contents) would indeed look like:
expdp user/pass schemas=<schemaname> directory=dumpdir \ dumpfile=<schemaname>.dmp \ logfile=expdp_<schemaname>.log
If you want to import to a different user/schema (the target database can be the same as the source), you can use:
impdp user/pass schemas=schema1 directory=dumpdir \ remap_schema=schema1:schema2 \ dumpfile=schema1.dmp \ logfile=impdp_schema2.log
If you don't want a complete import, you can set some filters both on data and metadata. See Filtering During Import Operations.
The Utilities Guide has all the details, I strongly recommend reading at least the overview part.
For importing the truncated tables, i.e you only want the data to be imported back to the table:
impdp user/pass TABLES=dept DIRECTORY=TEST_dir dumpfile=TEST.dmp logfile=expdpTEST.log TABLE_EXISTS_ACTION=REPLACE
Above my table is
deptwhich I want to import. I have truncated it earlier. From the dumpfile which is
expdpTEST.logI want only the data to be imported (the table structure will be the same so we use the parameter
If you have truncated 2 tables, for example
dept_idas the foreign key, then you need to import the
depttable first and then the
emptable to avoid errors during import.