True tablespace size in oracle

Question

I need to know true tablespace size in Oracle. I have some tablespace and I need to know how many space it uses now and how many space is free (and maybe percent of free space). I found in web some sqls but all of them showed size based on water mark... which is not true space allocated now but as far as I know the highest value which has ever been reached... So my real need is to know if I have enough space for my data which constantly are written and I must know how much of them I can store before having to delete some of them.

Thanks

Answer 1

Try this:

-- Available space, by tablespace

SELECT * FROM
  (SELECT tablespace_name FROM dba_tablespaces)
LEFT OUTER JOIN
  (SELECT tablespace_name, SUM(bytes) AS total_bytes
     FROM dba_data_files
     GROUP BY tablespace_name)
  USING (tablespace_name)
LEFT OUTER JOIN
  (SELECT tablespace_name, sum(bytes) AS used_bytes
     from dba_segments
     GROUP BY tablespace_name)
  USING (tablespace_name)
LEFT OUTER JOIN
  (SELECT tablespace_name, SUM(bytes) AS free_bytes
     FROM dba_free_space
     GROUP BY tablespace_name)
  USING (tablespace_name);