How do I reducethe size of sga?

Question

how do I reduce the size of sga so as to relief my heavily used server?

Answer 1

set echo off
set feedback off
set linesize 110
COLUMN a  HEADING ' '
COLUMN est_mb        FOR          99,999  HEADING 'Shared Pool|Size (MB)'
COLUMN multiplier    FOR            9.99  HEADING ' | |Multilpier'
COLUMN LC_MB         FOR           9,999  HEADING 'Lib. Cache|(MB)'
COLUMN LC_OBJ        FOR         999,999  HEADING 'Lib. Cache|Objects'
COLUMN LC_TS         FOR     999,999,999  HEADING 'Parse Time|Saved (Sec)'
COLUMN LC_TSF        FOR          999.99  HEADING 'Parse Time|Saved Factor'
COLUMN LC_OH         FOR     999,999,999  HEADING 'Lib. Obj.|Hits Change'
COLUMN sys_id        NOPRINT           new_value system_id
COLUMN sys_startup   NOPRINT           new_value startup_date
TTITLE Left    'DB :' system_id                      -
       Center 'Shared Pool Tuning Estimates'  Skip 1 -
       Left    'Up Since: ' startup_date             -
        Center '~~~~~~~~~~~~~~~~~~~~~~~~~~~~' Skip 2
select d.name                            AS sys_id,
       TO_CHAR(i.startup_time,'dd Mon yyyy hh24:mi') as sys_startup,
       p.SHARED_POOL_SIZE_FOR_ESTIMATE   AS est_MB,
       p.SHARED_POOL_SIZE_FACTOR         AS multiplier,
       p.ESTD_LC_SIZE                    AS LC_MB,
       p.ESTD_LC_MEMORY_OBJECTS          AS LC_OBJ,
       p.ESTD_LC_TIME_SAVED - base.ts              AS LC_TS,
       p.ESTD_LC_TIME_SAVED_FACTOR       AS LC_TSF,
       p.ESTD_LC_MEMORY_OBJECT_HITS - base.oh     AS LC_OH
  from V$SHARED_POOL_ADVICE p,
       v$database           d,
       v$instance           i,
       (SELECT ESTD_LC_TIME_SAVED         as ts,
               ESTD_LC_MEMORY_OBJECT_HITS as oh
          FROM V$SHARED_POOL_ADVICE
         WHERE SHARED_POOL_SIZE_FACTOR = 1)  base;
set echo off
set feedback off
set heading off
TTITLE Center 'Shared Pool Reserved' Skip 1 -
       Center '~~~~~~~~~~~~~~~~~~~~' Skip 2
select 'shared_pool_reserved_size init.ora paramater                     : '||to_char(value,'999,999,999')
  from v$parameter where name = 'shared_pool_reserved_size'
union all
select 'Freespace on reserved list                                       : '||to_char(FREE_SPACE,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Avg. size of free memory                                         : ' || to_char(AVG_FREE_SIZE,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Num. of free places on reserd list                               : '|| to_char(FREE_COUNT,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Largest piece of free memory on reserved list                    : ' || to_char(MAX_FREE_SIZE,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Total used memory on reserved list                               : ' ||to_char(USED_SPACE,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Average size of used memory on reserved list                     : '||to_char(AVG_USED_SIZE,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Number of used pieces of memory on reserved list                 : '|| to_char(USED_COUNT,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Largest piece of used memory on reserved lsit                    : ' || to_char(MAX_USED_SIZE,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Number of times reserved list searched for free memory           : '|| to_char(REQUESTS,'999,999,999')
  from v$shared_pool_reserved
union all
select '- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  '
  from dual
union all
select 'Number of times could reserved list has to start flushing LRU    : ' || to_char(REQUEST_MISSES,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Size of last memory request miss                                 : ' || to_char(LAST_MISS_SIZE,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Size of the largest memory request miss                          : ' ||to_char(MAX_MISS_SIZE,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Number of times no memory found (ORA-04031)                      : '||to_char(REQUEST_FAILURES,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Size of the last no memory found (ORA-04031)                     : '|| to_char(LAST_FAILURE_SIZE,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Minimum size of request that causes an ORA-04031 W/O flushing LRU: '|| to_char(ABORTED_REQUEST_THRESHOLD,'999,999,999,999')
  from v$shared_pool_reserved
union all
select 'Number of requests that signaled ORA-04031 without flushing LRU  : '|| to_char(ABORTED_REQUESTS,'999,999,999')
  from v$shared_pool_reserved
union all
select 'Size of last request that signaled ORA-04031                     : '|| to_char(LAST_ABORTED_SIZE,'999,999,999')
  from v$shared_pool_reserved;
TTITLE off
set feedback on
set heading on
set underline off
set feedback off
COLUMN TEXT          FOR a96        HEADING ''
SELECT     'V$SHARED_POOL_ADVICE displays information about estimated parse time savings in the shared pool for different sizes.'         ||
CHR(10) || '.'        ||
CHR(10) || 'SHARED POOL SIZE  : Shared pool size for the estimate (in MB).'        ||
CHR(10) || 'MULTIPLIER        : Size factor with respect to the current shared'   ||
CHR(10) || '                    pool size.  1.00 = current shared pool size.'      ||
CHR(10) || 'LIB. CACHE (MB)   : Est. memory in use by the library cache (in MB)'  ||
CHR(10) || 'LIB. CACHE OBJECTS: Est. number of library cache memory objects in'   ||
CHR(10) || '                    the shared pool of the specified size.'            ||
CHR(10) || 'PARSE TIME SAVED  : Est. elapsed parse time saved (in seconds), owing'||
CHR(10) || '                    to library cache memory objects being found in a' ||
CHR(10) || '                    shared pool of the specified size. This is the '  ||
CHR(10) || '                    time that would have been spent in reloading the' ||
CHR(10) || '                    required objects in the shared pool had they been'||
CHR(10) || '                    aged out due to insufficient amount of available' ||
CHR(10) || '                    free memory.'                                     ||
CHR(10) || 'PARSE TIME SAVED FACTOR: Estimated parse time saved factor with respect' ||
CHR(10) || '                         to the current shared pool size.'            ||
CHR(10) || 'LIB. OBJ. HITS    : Est. number of times a library cache memory object' ||
CHR(10) || '                    was found in a shared pool of the specified size.'
as text
FROM dual;
set underline '-'
TTITLE off
set feedback onThis will show you the state of shared pool and help you decide on the proper size.