How to Check Oracle Database Tablespace

When creating a new users in Oracle database (new schema), you need to verify the existing tablespace availability. This query will show you what's there and how much space are free to use.

SELECT df.tablespace_name "Tablespace",
  totalusedspace "Used MB",
  (df.totalspace - tu.totalusedspace) "Free MB",
  df.totalspace "Total MB",
  ROUND(100 * ( (df.totalspace - tu.totalusedspace)/ df.totalspace)) "% Free"
FROM
  (SELECT tablespace_name,
    ROUND(SUM(bytes) / 1048576) TotalSpace
  FROM dba_data_files
  GROUP BY tablespace_name
  ) df,
  (SELECT ROUND(SUM(bytes)/(1024*1024)) totalusedspace,
    tablespace_name
  FROM dba_segments
  GROUP BY tablespace_name
  ) tu
WHERE df.tablespace_name = tu.tablespace_name;

Also, this query will show where the tablespace file are located:

SELECT  FILE_NAME, BLOCKS, TABLESPACE_NAME
   FROM DBA_DATA_FILES;

Here are some references on how Oracle manages user, schema and tablespace.

https://community.oracle.com/message/1832920http://docs.oracle.com/cd/B28359_01/server.111/b28310/tspaces014.htm#ADMIN11412

http://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_8003.htm

http://stackoverflow.com/questions/880230/difference-between-a-user-and-a-schema-in-oracle

https://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:6162110256950