Oracle Library Cache Object loaded into SGA

今天在测试数据库发现alert出现警告错误

Memory Notification: Library Cache Object loaded into SGA
Heap size 2919K exceeds notification threshold (2048K)
KGL object name :select
    service_name, uio_waits, uio_time, con_waits, con_time,
    adm_waits, adm_time, net_waits, net_time
  from
    (select
      stat1.service_name service_name, db_time, uio_waits, uio_time,
      con_waits, con_time, adm_waits, adm_time, net_waits, net_time
    from
      (select s1.service_name,
              sum(decode(s1.stat_name, 'DB time', s1.diff, 0)) db_time
      from
        (select e.service_name    service_name,
                e.stat_name        stat_name,
           
Tue May  6 11:12:12 2014
Memory Notification: Library Cache Object loaded into SGA
Heap size 2757K exceeds notification threshold (2048K)
Details in trace file /u01/app/Oracle/admin/amidb/udump/amidb_or

后来在网上查了一下原来是在Oracle 10.2.0.1版本数据库中隐含参数_kgl_large_heap_warning_threshold默认值是2M，该参数控制加载到内存中对象的大小，当加载的对象大于2M时，就会在alert警告文件中进行提示。2M的默认大小相对太小，因此在10.2.0.1版本中可能很容易遇到这个报错信息。该参数默认值在10.2.0.2版本中进行了调整，调整到了50M。

alter system set "_kgl_large_heap_warning_threshold"=52428800 scope=spfile;

System altered.