Tablespacefree

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Tablespacefree

  1. 1. Free Space in a Tablespace Administration TipsFinding the amount of used and free space in a TablespaceThe following bit of SQL will do the trick:SELECT TABLESPACE_NAME,ROUND(SUM(TOTAL_MB)-SUM(FREE_MB)) MB_USED,ROUND(SUM(TOTAL_MB)) MB_SIZE,ROUND((SUM(TOTAL_MB)-SUM(FREE_MB))/SUM(TOTAL_MB)*100) PCT_FULL,ROUND(SUM(MAX_MB) - (SUM(TOTAL_MB)-SUM(FREE_MB))) MB_FREE,ROUND(SUM(MAX_MB)) MB_MAXSIZE,ROUND((SUM(TOTAL_MB)-SUM(FREE_MB))/SUM(MAX_MB)*100) PCT_UTILFROM(SELECT TABLESPACE_NAME,SUM(BYTES)/1024/1024 FREE_MB,0 TOTAL_MB,0 MAX_MBFROM DBA_FREE_SPACE GROUP BY TABLESPACE_NAMEUNIONSELECT TABLESPACE_NAME,0 CURRENT_MB,SUM(BYTES)/1024/1024 TOTAL_MB,SUM(DECODE(MAXBYTES, 0, BYTES, MAXBYTES))/1024/1024 MAX_MBFROM DBA_DATA_FILES GROUP BY TABLESPACE_NAME)GROUP BY TABLESPACE_NAME;Youll get a report that looks a bit like this:TABLESPACE_NAME MB_USED MB_SIZE PCT_FULL MB_FREE MB_MAXSIZE PCT_UTIL--------------- ---------- ---------- ---------- ---------- ---------- ----------INDX 0 25 0 16384 16384 0SYSTEM 87 325 27 16297 16384 1UNDOTBS 1 200 1 16383 16384 0USERS 0 25 0 16384 16384 0The various columns can be explained thus:MB_USED: Total amount of space currently in use within a tablespaceMB_SIZE: Total size of the tablespace, adding up the physical sizes of all datafilesPCT_FULL: Used divided by Size, expressed as a percentageMB_FREE: Total amount of tablespace still sitting there emptyMB_MAXSIZE: This shows how big the tablespace can become. Often this will be the same as the MB_SIZE column -but not if youve switched on autoextend, in which case this column will show the maxsize parameterPCT_UTIL: Size divided by Maxsize expressed as a percentageIn other words, PCT_FULL shows you what percentage of what youve currently got is beingused, whereas PCT_UTIL shows what percentage of the maximum you could possibly *oneday* have is being used. Personally, I wouldnt touch autoextend with a barge pole, and Idbe looking to resize or add extra datafiles when the PCT_FULL column is reaching aroundthe 75 - 80% mark.Copyright © Howard Rogers 2001 10/17/2001 Page 1 of 1

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