What should be considered when querying tablespace in Oracle?

There are several important considerations to keep in mind when querying Oracle table spaces.

1. Tablespace Name: To confirm the correct name of the tablespace being queried, you can use the command SELECT tablespace_name FROM dba_tablespaces; to query the names of all tablespaces.
2. Check the tablespace usage: Verify if the queried tablespace has enough space to accommodate data and indexes. You can use the query SELECT tablespace_name, sum(bytes)/1024/1024 as “Total Size (MB)”, sum(bytes – bytes_free)/1024/1024 as “Used Size (MB)”, sum(bytes_free)/1024/1024 as “Free Size (MB)” FROM dba_free_space GROUP BY tablespace_name; to check the tablespace usage.
3. Data files: verify if the data files for the queried table space exist and are accessible. You can use the query SELECT file_name, tablespace_name, bytes/1024/1024 as “File Size (MB)”, status FROM dba_data_files; to retrieve information on all data files.
4. Tablespace type: Confirm whether the tablespace being queried is used for storing data or storing indexes. You can use the query SELECT tablespace_name, segment_type FROM dba_segments WHERE tablespace_name=’YOUR_TABLESPACE_NAME’; to determine the type of objects stored in the tablespace.
5. Tablespace permissions: Verify if the user you are querying has the permission to access the tablespace. You can use the query SELECT * FROM dba_tab_privs WHERE grantee=’YOUR_USER’; to check the user’s permissions.
6. Tablespace associated objects: When querying a tablespace, you can also query objects such as tables, indexes, etc. You can use the query SELECT * FROM dba_tables WHERE tablespace_name=’YOUR_TABLESPACE_NAME’; to retrieve all tables in a specified tablespace.

In summary, when querying Oracle table spaces, it is important to confirm details such as the table space name, usage, data files, type, permissions, and associated objects.