Oracle Automating Script for KEEP Pool Caching Tables & Indexes db_keep_cache_size

Oracle Database Tips by Donald Burleson

Note: The BUFFER_POOL_KEEP and BUFFER_POOL_RECYCLE pool parameters have been deprecated in release 12c.

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Another method for identifying tables and indexes for the KEEP pool examines the current blocks in the data buffer. For this query, the rules are simple. Any object that has more than 80% of its data blocks in the data buffer should probably be fully-cached. It is highly unlikely that an undeserving table of index would meet this criterion. Of course, you would need to run this script at numerous times during the day because the buffer contents change very rapidly. The following script can be run every hour via dbms_job, and automate the monitoring of KEEP pool candidates. Every time it finds a candidate, the DBA will execute the syntax and adjust the total KEEP pool size to accommodate the new object.

set pages 999

set lines 92

spool keep_syn.lst

drop table t1;

create table t1 as
select
   o.owner          owner,
   o.object_name    object_name,
   o.subobject_name subobject_name,
   o.object_type    object_type,
   count(distinct file# || block#)         num_blocks
from
   dba_objects o,
   v$bh         bh
where
   o.data_object_id = bh.objd
and
   o.owner not in ('SYS','SYSTEM')
and
bh.status != 'free'
group by
   o.owner,
   o.object_name,
   o.subobject_name,
   o.object_type
order by
   count(distinct file# || block#) desc
;

select
   'alter '||s.segment_type||' '||t1.owner||'.'||s.segment_name||' storage (buffer_pool keep);'
from
   t1,
   dba_segments s
where
   s.segment_name = t1.object_name
and
   s.owner = t1.owner
and
   s.segment_type = t1.object_type
and
   nvl(s.partition_name,'-') = nvl(t1.subobject_name,'-')
and
   buffer_pool <> 'KEEP'
and
   object_type in ('TABLE','INDEX')
group by
   s.segment_type,
   t1.owner,
   s.segment_name
having
   (sum(num_blocks)/greatest(sum(blocks), .001))*100 > 80
;

spool off;

alter TABLE BOM.BOM_DELETE_SUB_ENTITIES storage (buffer_pool keep);
alter TABLE BOM.BOM_OPERATIONAL_ROUTINGS storage (buffer_pool keep);
alter INDEX BOM.CST_ITEM_COSTS_U1 storage (buffer_pool keep);
alter TABLE APPLSYS.FND_CONCURRENT_PROGRAMS storage (buffer_pool keep);
alter TABLE APPLSYS.FND_CONCURRENT_REQUESTS storage (buffer_pool keep);
alter TABLE GL.GL_JE_BATCHES storage (buffer_pool keep);
alter INDEX GL.GL_JE_BATCHES_U2 storage (buffer_pool keep);
alter TABLE GL.GL_JE_HEADERS storage (buffer_pool keep);
alter TABLE INV.MTL_DEMAND_INTERFACE storage (buffer_pool keep);
alter INDEX INV.MTL_DEMAND_INTERFACE_N10 storage (buffer_pool keep);
alter TABLE INV.MTL_ITEM_CATEGORIES storage (buffer_pool keep);
alter TABLE INV.MTL_ONHAND_QUANTITIES storage (buffer_pool keep);
alter TABLE INV.MTL_SUPPLY_DEMAND_TEMP storage (buffer_pool keep);
alter TABLE PO.PO_REQUISITION_LINES_ALL storage (buffer_pool keep);
alter TABLE AR.RA_CUSTOMER_TRX_ALL storage (buffer_pool keep);
alter TABLE AR.RA_CUSTOMER_TRX_LINES_ALL storage (buffer_pool keep);
alter INDEX WIP.WIP_REQUIREMENT_OPERATIONS_N3 storage (buffer_pool keep);

In sum, there are two ways to identify tables and indexes for full caching in the KEEP pool. We start by explaining all of the SQL in the databases looking for small-table, full-table scans. Next, we repeatedly examine the data buffer cache, seeing any objects that have more than 80% of their blocks in RAM.

Next, let's finish the job and see how to re-size the KEEP pool to accommodate your new objects.The following script can be run every hour via dbms_job, and automate the monitoring of KEEP pool candidates. Every time it finds a candidate, the DBA will execute the syntax and adjust the total KEEP pool size to accommodate the new object.

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