-- QUERY 1 - datafile Allocated space,free space,High Water Mark location,%Free and resizeable MB
select
tablespace_name,
file_id,
file_name DATA_FILE_NAME,
Allocated_MBYTES,
High_Water_Mark_MBYTES,
FREE_MBYTES,
trunc((FREE_MBYTES/Allocated_MBYTES)*100,2) "% Free",
trunc(Allocated_MBYTES-High_Water_Mark_MBYTES,2) Resizeble
from
(
select
ddf.tablespace_name tablespace_name,
ddf.file_id file_id,
ddf.file_name file_name,
ddf.bytes/1024/1024 Allocated_MBYTES,
trunc((ex.hwm*(dt.block_size))/1024/1024,2) High_Water_Mark_MBYTES,
FREE_MBYTES
from
dba_data_files ddf,
dba_tablespaces dt,
(
select file_id, sum(bytes/1024/1024) FREE_MBYTES
from dba_free_space
group by file_id
) free,
(
select file_id, max(block_id+blocks) hwm
from dba_extents
group by file_id
) ex
where ddf.file_id = ex.file_id
and ddf.tablespace_name = dt.tablespace_name
and ddf.file_id = free.file_id (+)
order by ddf.tablespace_name, ddf.file_id
);
-- QUERY 2 - location of segments within a datafile (Provide file_id of the Tablespace)
select
file_name data_file_name,
segment_type,
owner||'.'||segment_name segment_name,
partition_name,
block_id,
blockId_Mbytes
from
(
select
de.owner owner,
de.segment_name segment_name,
de.segment_type segment_type,
de.block_id block_id,
DE.PARTITION_NAME partition_name,
ddf.file_name file_name,
trunc((de.block_id*(dt.block_size))/1024/1024,2) blockId_Mbytes
from
dba_extents de, dba_data_files ddf, dba_tablespaces dt
where ddf.file_id = &file_id
and ddf.file_id = de.file_id
and ddf.tablespace_name = dt.tablespace_name
order by de.block_id desc
)
where rownum <= 100;
To re-size the DATAFILE the only way is to lower the High Water Mark. This can be done by moving extents to other Tablespace or the same Tablespace. Check the size of Tablesapce before moving. In production database it’s not easy to move table, LOB etc singe many user can accessing these objects. Index can be move by rebuilding online in production database. After moving the tables it’s necessary to rebuild the UNUSABLE indexes on the tables.