Tuesday, September 15, 2009

Estimate Tablespace growth

Some time it is very helpful to plan disk space/ tablespace management if you estimate the growth of your tablespace. Here is a select query which can be helpful :

SELECT TO_CHAR (sp.begin_interval_time,'DD-MM-YYYY') days
, ts.tsname
, max(round((tsu.tablespace_size* dt.block_size )/(1024*1024),2) ) cur_size_MB
, max(round((tsu.tablespace_usedsize* dt.block_size )/(1024*1024),2)) usedsize_MB
FROM DBA_HIST_TBSPC_SPACE_USAGE tsu
, DBA_HIST_TABLESPACE_STAT ts
, DBA_HIST_SNAPSHOT sp
, DBA_TABLESPACES dt
WHERE tsu.tablespace_id= ts.ts#
AND tsu.snap_id = sp.snap_id
AND ts.tsname = dt.tablespace_name
AND ts.tsname NOT IN ('SYSAUX','SYSTEM')
GROUP BY TO_CHAR (sp.begin_interval_time,'DD-MM-YYYY'), ts.tsname
ORDER BY ts.tsname, days;


Another One: This query gives average increase per day 

SELECT b.tsname tablespace_name
, MAX(b.used_size_mb) cur_used_size_mb
, round(AVG(inc_used_size_mb),2)avg_increas_mb
FROM (
  SELECT a.days, a.tsname, used_size_mb
  , used_size_mb - LAG (used_size_mb,1)  OVER ( PARTITION BY a.tsname ORDER BY a.tsname,a.days) inc_used_size_mb
  FROM (
      SELECT TO_CHAR(sp.begin_interval_time,'MM-DD-YYYY') days
       ,ts.tsname
       ,MAX(round((tsu.tablespace_usedsize* dt.block_size )/(1024*1024),2)) used_size_mb
      FROM DBA_HIST_TBSPC_SPACE_USAGE tsu, DBA_HIST_TABLESPACE_STAT ts
       ,DBA_HIST_SNAPSHOT sp, DBA_TABLESPACES dt
      WHERE tsu.tablespace_id= ts.ts# AND tsu.snap_id = sp.snap_id
       AND ts.tsname = dt.tablespace_name  AND sp.begin_interval_time > sysdate-7
      GROUP BY TO_CHAR(sp.begin_interval_time,'MM-DD-YYYY'), ts.tsname
      ORDER BY ts.tsname, days
  ) A
) b GROUP BY b.tsname ORDER BY b.tsname;


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