latch_types.sql

 

This scripts prints a list of the latch types, and reports the number of child latches for each type. If a latch type has multiple child latches, V$LATCH_CHILDREN can be used to determine whether activity against the child latches is evenly distributed. V$LATCH_PARENT should also be checked to see whether there has been any activity against the parent latch.

 

 

 

 

column type_num format 999 heading "TYPE|NUMBER"
column type_name format a45 heading "TYPE|NAME"
column parent format 9 heading "PARENT|LATCH"
column children format 999999 heading "CHILD|LATCHES"

select
  l.kslltnum  type_num,
  d.kslldnam  type_name,
  sum(decode(l.kslltcnm, 0, 1, null))  parent,
  sum(decode(l.kslltcnm, 0, null, 1))  children
from
  sys.x$kslld  d,
  sys.x$ksllt  l
where
  d.inst_id = userenv('Instance') and
  l.inst_id = userenv('Instance') and
  l.kslltnum = d.indx
group by
  l.kslltnum,
  d.kslldnam
order by
  l.kslltnum,
  d.kslldnam