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Don Burleson Blog 







Size of Oracle database

Oracle Database Tips by Donald BurlesonNovember 27, 2015

Question:  I to know the size of my Oracle database.  Is there a table that shows the total size of an Oracle database.

Answer: There are several ways to measure the size of an Oracle database:

1 - The size of the Oracle database files can be computed several ways:

-- get database size from v$datafile:

select round((sum(bytes)/1048576/1024),2) from v$datafile;

-- get Oracle database size from dba_data_files:
"Reserved_Space(MB)", "Reserved_Space(MB)" - "Free_Space(MB)" "Used_Space(MB)","Free_Space(MB)"
(select sum(bytes/(1014*1024)) from dba_data_files) "Reserved_Space(MB)",
(select sum(bytes/(1024*1024)) from dba_free_space) "Free_Space(MB)"
from dual

2 - The size of the sum of table extents

   segment_name table_name,
   sum(bytes)/(1024*1024) table_size_meg
   segment_name = 'MYTAB'
See code depot for full scripts.

3 - The sum of the size of the data within the tables

You can also compute the size of an Oracle database over time.  In Oracle 10g and beyond we have the dba_hist_seg_stat table with a wealth of information about all active segments within the database, including the space usage in the space_allocated_total and space_used_total columns.

This script will show "spaced used total" (total size) for a specific Oracle table, essentially computing the Oracle table size over time:

col c1 format a15 heading 'snapshot|date'
col c2 format a25 heading 'table|name'
col c3 format 999,999,999 heading 'space|used|total'
to_char(begin_interval_time,'yy/mm/dd hh24:mm') c1,
object_name c2,
space_used_total c3
dba_hist_seg_stat s,
dba_hist_seg_stat_obj o,
dba_hist_snapshot sn
o.owner = 'SCHEMA_07'
s.obj# = o.obj#
sn.snap_id = s.snap_id
object_name like 'XIF2%'
order by

For a complete set of Oracle size scripts you can download the Oracle scripts collection.


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