Database Growth History and Forecast

To get information about individual tablespaces growth history and forecast, please see my article and scripts by clicking here.

Starting Oracle 10G, Oracle records tablespaces usage (allocated, used etc.) in AWR which can be retrieved by querying the data dictionary view dba_hist_tbspc_space_usage. Using information in dba_hist_tbspc_space_usage, following script can be used to view the history of database usage and predict the expected growth for the future. Growth forecast is based on daily growth in the past.

Things to note:
1) This script is based on AWR. If your AWR retention period is 7 days, this script can only tell the growth history of last 7 days and predict based on last 7 days growth. I would recommend to have AWR retention to at least 30 days - this will also be more helpful in case of performance tuning situation as you will have a longer window of the past to look into for performance comparisons.
2) This script does not including TEMP and UNDO tablespaces while analyzing and forecasting
3) You may edit this scrip according to your requirement to forecast for a period  which suites your requirements. By default it will predict expected growth for next 30, 60 and 90 days.
4) Log in as user SYS on SQLPLUS and copy and paste the following code.

##############################################
set serverout on
set verify off
set lines 200
set pages 2000
DECLARE
v_ts_id number;
v_ts_block_size number;
v_begin_snap_id number;
v_end_snap_id number;
v_begin_snap_date date;
v_end_snap_date date;
v_numdays number;
v_ts_begin_size number;
v_ts_end_size number;
v_ts_growth number;
v_ts_begin_allocated_space number;
v_ts_end_allocated_space number;
v_db_begin_size number := 0;
v_db_end_size number := 0;
v_db_begin_allocated_space number := 0;
v_db_end_allocated_space number := 0;
v_db_growth number := 0;
cursor v_cur is select tablespace_name from dba_tablespaces where contents='PERMANENT';

BEGIN

FOR v_rec in v_cur
LOOP

BEGIN
v_ts_begin_allocated_space := 0;
v_ts_end_allocated_space := 0;
v_ts_begin_size := 0;
v_ts_end_size := 0;

SELECT ts# into v_ts_id FROM v$tablespace where name = v_rec.tablespace_name;
SELECT block_size into v_ts_block_size FROM dba_tablespaces where tablespace_name = v_rec.tablespace_name;
SELECT min(snap_id), max(snap_id), min(trunc(to_date(rtime,'MM/DD/YYYY HH24:MI:SS'))), max(trunc(to_date(rtime,'MM/DD/YYYY HH24:MI:SS')))
into v_begin_snap_id,v_end_snap_id, v_begin_snap_date, v_end_snap_date from dba_hist_tbspc_space_usage where tablespace_id=v_ts_id;
v_numdays := v_end_snap_date - v_begin_snap_date;

SELECT round(max(tablespace_size)*v_ts_block_size/1024/1024,2) into v_ts_begin_allocated_space from dba_hist_tbspc_space_usage where tablespace_id=v_ts_id and snap_id = v_begin_snap_id;
SELECT round(max(tablespace_size)*v_ts_block_size/1024/1024,2) into v_ts_end_allocated_space from dba_hist_tbspc_space_usage where tablespace_id=v_ts_id and snap_id = v_end_snap_id;
SELECT round(max(tablespace_usedsize)*v_ts_block_size/1024/1024,2) into v_ts_begin_size from dba_hist_tbspc_space_usage where tablespace_id=v_ts_id and snap_id = v_begin_snap_id;
SELECT round(max(tablespace_usedsize)*v_ts_block_size/1024/1024,2) into v_ts_end_size from dba_hist_tbspc_space_usage where tablespace_id=v_ts_id and snap_id = v_end_snap_id;

v_db_begin_allocated_space := v_db_begin_allocated_space + v_ts_begin_allocated_space;
v_db_end_allocated_space := v_db_end_allocated_space + v_ts_end_allocated_space;
v_db_begin_size := v_db_begin_size + v_ts_begin_size;
v_db_end_size := v_db_end_size + v_ts_end_size;
v_db_growth := v_db_end_size - v_db_begin_size;

END;
END LOOP;

DBMS_OUTPUT.PUT_LINE(CHR(10));
DBMS_OUTPUT.PUT_LINE('Summary');
DBMS_OUTPUT.PUT_LINE('========');
DBMS_OUTPUT.PUT_LINE('1) Allocated Space: '||v_db_end_allocated_space||' MB'||' ('||round(v_db_end_allocated_space/1024,2)||' GB)');
DBMS_OUTPUT.PUT_LINE('2) Used Space: '||v_db_end_size||' MB'||' ('||round(v_db_end_size/1024,2)||' GB)');
DBMS_OUTPUT.PUT_LINE('3) Used Space Percentage: '||round(v_db_end_size/v_db_end_allocated_space*100,2)||' %');
DBMS_OUTPUT.PUT_LINE(CHR(10));
DBMS_OUTPUT.PUT_LINE('History');
DBMS_OUTPUT.PUT_LINE('========');
DBMS_OUTPUT.PUT_LINE('1) Allocated Space on '||v_begin_snap_date||': '||v_db_begin_allocated_space||' MB'||' ('||round(v_db_begin_allocated_space/1024,2)||' GB)');
DBMS_OUTPUT.PUT_LINE('2) Current Allocated Space on '||v_end_snap_date||': '||v_db_end_allocated_space||' MB'||' ('||round(v_db_end_allocated_space/1024,2)||' GB)');
DBMS_OUTPUT.PUT_LINE('3) Used Space on '||v_begin_snap_date||': '||v_db_begin_size||' MB'||' ('||round(v_db_begin_size/1024,2)||' GB)' );
DBMS_OUTPUT.PUT_LINE('4) Current Used Space on '||v_end_snap_date||': '||v_db_end_size||' MB'||' ('||round(v_db_end_size/1024,2)||' GB)' );
DBMS_OUTPUT.PUT_LINE('5) Total growth during last '||v_numdays||' days between '||v_begin_snap_date||' and '||v_end_snap_date||': '||v_db_growth||' MB'||' ('||round(v_db_growth/1024,2)||' GB)');
IF (v_db_growth <= 0 OR v_numdays <= 0) THEN
DBMS_OUTPUT.PUT_LINE(CHR(10));
DBMS_OUTPUT.PUT_LINE('No data growth was found for the Database');
ELSE
DBMS_OUTPUT.PUT_LINE('6) Per day growth during last '||v_numdays||' days: '||round(v_db_growth/v_numdays,2)||' MB'||' ('||round((v_db_growth/v_numdays)/1024,2)||' GB)');
DBMS_OUTPUT.PUT_LINE(CHR(10));
DBMS_OUTPUT.PUT_LINE('Expected Growth');
DBMS_OUTPUT.PUT_LINE('===============');
DBMS_OUTPUT.PUT_LINE('1) Expected growth for next 30 days: '|| round((v_db_growth/v_numdays)*30,2)||' MB'||' ('||round(((v_db_growth/v_numdays)*30)/1024,2)||' GB)');
DBMS_OUTPUT.PUT_LINE('2) Expected growth for next 60 days: '|| round((v_db_growth/v_numdays)*60,2)||' MB'||' ('||round(((v_db_growth/v_numdays)*60)/1024,2)||' GB)');
DBMS_OUTPUT.PUT_LINE('3) Expected growth for next 90 days: '|| round((v_db_growth/v_numdays)*90,2)||' MB'||' ('||round(((v_db_growth/v_numdays)*90)/1024,2)||' GB)');
DBMS_OUTPUT.PUT_LINE(CHR(10));
DBMS_OUTPUT.PUT_LINE('If no data is displayed, it means that AWR does not have data about at least one tablespace of this database');
DBMS_OUTPUT.PUT_LINE('Execute DBMS_WORKLOAD_REPOSITORY.CREATE_SNAPSHOT, or wait for next AWR snapshot capture before executing this script');
DBMS_OUTPUT.PUT_LINE('/\/\/\/\/\/\/\/\/\/\/ END \/\/\/\/\/\/\/\/\/\/\');

END IF;

EXCEPTION
WHEN NO_DATA_FOUND THEN
DBMS_OUTPUT.PUT_LINE(CHR(10));
DBMS_OUTPUT.PUT_LINE('====================================================================================================================');
DBMS_OUTPUT.PUT_LINE('One or more Tablespaces usage information not found in AWR');
DBMS_OUTPUT.PUT_LINE('Execute DBMS_WORKLOAD_REPOSITORY.CREATE_SNAPSHOT, or wait for next AWR snapshot capture before executing this script');
DBMS_OUTPUT.PUT_LINE('====================================================================================================================');

END;
/
##############################################

Please give your feedback if you find any difficulty in executing this script or if this script does not work for you.

Sample Output

Summary
========
1) Allocated Space: 42492 MB (41.5 GB)
2) Used Space: 30806.5 MB (30.08 GB)
3) Used Space Percentage: 72.5 %


History
========
1) Allocated Space on 07-DEC-14: 38776 MB (37.87 GB)
2) Current Allocated Space on 11-JAN-15: 42492 MB (41.5 GB)
3) Used Space on 07-DEC-14: 26445.89 MB (25.83 GB)
4) Current Used Space on 11-JAN-15: 30806.5 MB (30.08 GB)
5) Total growth during last 35 days between 07-DEC-14 and 11-JAN-15: 4360.61 MB (4.26 GB)
6) Per day growth during last 35 days: 124.59 MB (.12 GB)


Expected Growth
===============
1) Expected growth for next 30 days: 3737.67 MB (3.65 GB)
2) Expected growth for next 60 days: 7475.33 MB (7.3 GB)
3) Expected growth for next 90 days: 11213 MB (10.95 GB)

If no data is displayed, it means that AWR does not have data about at least one tablespace of this database
Execute DBMS_WORKLOAD_REPOSITORY.CREATE_SNAPSHOT, or wait for next AWR snapshot capture before executing this script

/\/\/\/\/\/\/\/\/\/\/ END \/\/\/\/\/\/\/\/\/\/\