I am going to perform an upgrade on a Hadoop cluster but am wanting to backup the Ambari metastore schema first in case anything goes wrong.
Oracle is used to store the data, so I looked at using expdp to make a quick backup of the schema in its current state. However, I see in several different documents it is mentioned this is used to "unload" data. Does that mean the data will be removed from the database during the dump process? I want to keep everything in place and just make a quick backup, similar to the Postgres command pg_dump.
Don't worry, your data will stay where it is.
Here's a simple example: I'm exporting Scott's DEPT table. You'll see that data is in the table before and after EXPDP was executed.
SQL> select * from dept;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
SQL> $expdp scott/tiger@xe tables=dept directory=ext_dir
Export: Release 11.2.0.2.0 - Production on Pon O×u 5 21:21:24 2018
Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 11g Express Edition Release 11.2.0.2.0 - 64bit Production
Starting "SCOTT"."SYS_EXPORT_TABLE_01": scott/********@xe tables=dept directory=ext_dir
Estimate in progress using BLOCKS method...
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 64 KB
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/INDEX/INDEX
Processing object type TABLE_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type TABLE_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
. . exported "SCOTT"."DEPT" 5.929 KB 4 rows
Master table "SCOTT"."SYS_EXPORT_TABLE_01" successfully loaded/unloaded
******************************************************************************
Dump file set for SCOTT.SYS_EXPORT_TABLE_01 is:
C:\TEMP\EXPDAT.DMP
Job "SCOTT"."SYS_EXPORT_TABLE_01" successfully completed at 21:21:34
SQL> select * from dept;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
SQL>