1. Query the V$FIXED_TABLE to determine the V$ views that provide latch information.
| a. Execute the following query:> select name from v$fixed_table where name like 'V$LATCH%'; |
2. Remember that there are 14 levels of latches, numbered 0 – 13.
| a. Take a look at three common latches and their level by executing the following query:> select name, level# from v$latch where name in
('cache buffers chain','library cache','redo allocation');
You may or may not see each of these latches listed depending upon the state and activity on your database. |
3. Each parent and child latch has one instance in X$KSLLT.
| a. Execute the following query to view a KSLLT structure for a latch:> select v$latch_parent.addr,v$latch_parent.level#,v$latch_parent.latch#,
v$latch_parent.name
from v$latch_parent,x$ksllt
where v$latch_parent.addr = x$ksllt.addr;
You should at least see information for the ‘latch wait list’ latch. However, your results will vary depending upon the state and activity of your database. |
4. Using the latch# from the previous query, you can query the X$KSLLD table to see the array of latch descriptors.
