Database BACKUP

iit used Ask the Experts™

I want to backup my database, including tables, constraints, procedures,packages, primary keys, indexes etc.

I have found DBMS_METADATA.GET_DEPENDENT_DDL() function helpful

I also found this link helpful

In the section "Issues with dbms_metadata"

When you have foreign keys (“references” constraints), it would be nice to punch the table DDL in their proper order for re-loading into another database.  If you do not order the table, a table may be added that references another table that has not yet been added.  Making this change would involve adding a WHERE clause that queries dba_constraints and dba_cons_columns to determine the proper table order.

How do I use dba_constraints and dba_cons_columns to retrieve the table in the proper order?
Any example would be highly appreciated.

thank you very much for all your help!

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if you really want to backup my database, including tables, constraints, procedures,packages, primary keys, indexes etc.

The export/import is easy way for you. the export file, usually called dump file, includes all the DDLs and data for all the database objects.

export/import are two utility shipped with oracle. In oracle 8i,they are exp.exe and imp.exe.

in the command prompt:
assume you work on windows(same as on unix)
C>exp help=y

usually, you have 3 ways to export data from the database.

FULL,OWNER and Table


to export the whole database:
(You need to have EXP_FULL_DATABASE privilege. )
C:>exp system/manager@service_name  full=y file=ABCD.dmp log=ABCD_exp.log

to export a schema(all the database objects belong to the user):

C:>exp scott/tiger@service_name  file=ABCD.dmp owner=SCOTT log=ABCD_exp.log

to export tables:

C:>exp scott/tiger@service_name  file=ABCD.dmp tables=(exp,dept) log=ABCD_exp.log

if you do not want the records in the tables, you can use rows=N to do that.

For more details, see :
Top Expert 2008

Export, Import is a good choice.
for other possibility.


thank you for the comments.

I agree exp/imp are great tools to backup. I should have posted my clearly like this,

I want to *extract ddl* that creates my whole database with package, procedures, tables etc. For this dbms_metadata.get_ddl is a great tool. But, as discussed at this link

there might be problems creating the db when tables have referential constraints, unless the parent tables in the relationship are created first.  It is discussed in the section "Issues with dbms_metadata"
My question is
How do I use dba_constraints and dba_cons_columns to retrieve the tables in the proper order?

sorry for the confusion.

thank you very much for your comments!
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KongAWS Certified Solutions Architect - Professional

You could write a convoluted query/sub-program to do this but the problem will be with circular referencing tables.

Make your life easier, create all tables first or run the resultant scripts from get_ddl a few times ignoring the ORA-00955 errors. Oracle does it all the time - ever seen the output of running catalog.sql and catproc.sql? :-)


Kong: Thank you for the comments.

Do you have any such sample scripts?
KongAWS Certified Solutions Architect - Professional
iit, use dbms_metadata.get_ddl function to get the ddl, you can generate the scripts to call the function eg:

SELECT 'SELECT dbms_metadata.get_ddl(''' || object_type
       || ''', ''' || object_name || ''') FROM DUAL;'
  FROM user_objects

Then run the results. RE: referencial constraints - don't bother writing a script that creates tables in the right order, no script will handle circular dependencies.



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