Saturday, April 30, 2011

Heap size 2238K exceeds notification threshold (2048K) in 10.2.0.1

Symptom:

Heap size 2238K exceeds notification threshold (2048K)
KGL object name :SELECT /*+rule*/ SYS_XMLGEN(VALUE(KU$), XMLFORMAT.createFormat2('TABLE_T', '7')), KU$.OBJ_NUM FROM SYS.KU$_HTABLE_VIEW KU$ WHERE NOT (BITAND
(KU$.PROPERTY,8192)=8192) AND NOT BITAND(KU$.SCHEMA_OBJ.FLAGS,128)!=0 AND KU$.SCHEMA_OBJ.NAME=:NAME1 AND KU$.SCHEMA_OBJ.OWNER_NAME=:SCHEMA2

Solution/Explanation:

The default threshold in 10.2.0.1 is 2M. So these messages could show up frequently in some application environments.

In 10.2.0.2, the threshold was increased to 50MB after regression tests, so this should be a reasonable and recommended value.

In 10g we have a new undocumented parameter that sets the KGL heap size warning threshold. This parameter was not present in 10gR1. Warnings are written if heap size exceeds this threshold.

Set _kgl_large_heap_warning_threshold to a reasonable high value or zero to prevent these warning messages. Value needs to be set in bytes.

If you want to set this to 8192 (8192 * 1024) and are using an spfile:

(logged in as "/ as sysdba")

SQL> alter system set "_kgl_large_heap_warning_threshold"=8388608 scope=spfile ;

SQL> shutdown immediate

SQL> startup