Oracle Session Tracing Part IV

Part IV in our series will focus on determining which internal Oracle views hold the information to our enabled statistical gathering.

• In Part I, we learned how to set the CLIENT_IDENTIFIER session variable to more accurately pinpoint resource consumption for an individual user or group of users.
• In Part II, we learned how to set the ACTION and MODULE name so that we could track where in our code transactions were being executed and track the use of resources by transaction type or section of code.
• In Part III, we focused on enabling tracing of statistics through the DBMS_MONITOR package.
• Now in part IV of this series we will look at the internal views within Oracle that keep track of the enabled statistics gathering enabled in Part III.

In Part III, we left off displaying the enabled traces and statistic gatherings we enabled through the DBMS_MONITOR package. Recall that in Part III we queried the DBA_ENABLED_AGGREGATIONS view and had a listing such as in Listing 1. Table 1 gives a breakdown of the DBA_ENABLED_AGGREGATIONS view as I have renamed some of the columns for Listing 1.

SQL> SELECT * FROM DBA_ENABLED_AGGREGATIONS ;

AGGREGATION          SERVICE              MODULE               ACTION
-------------------- -------------------- -------------------- --------------------
CLIENT_ID            webclient
SERVICE_MODULE       ACCT                 PAYROLL

In the last three parts of this series, we have also zeroed in on setting different session environment variables. Those variables were CLIENT_IDENTIFIER, ACTION, and MODULE. We have also tracked some of the sessions by SID, SESSION_ID, SERVICE_NAME, and SERIAL#. I thought it might be interesting to look at where within Oracle's internal views these columns might be defined since this could help us in future needs of our investigation. Instead of searching through the endless documentation of Oracle, I instead decided to produce a query (Listing 2) in which I queried the DBA_TAB_COLUMNS view to look at what internal Oracle views or objects have these columns in common. From the output, I can then look at the definitions of those named objects that intrigue me. Listing 2 is only a partial listing and I encourage you to execute the query and see the total output. That way if you are ever interested in searching for a single column or combination of columns you will know where within the Oracle internal views this information is stored. Do not take this output too lightly. If you remember that we were enabling statistics gathering and tracing in the previous parts to this article for combinations of these columns, you can quickly see where in this listing the information is kept and where aggregates on columns are stored. Also, be warned that most of the output you will see are for Oracle's workload repository, advisories, and snapshots mechanisms and are not of any real use unless you are using those utilities. For us I have only left the objects we will be concerned with for looking at the gathered statistics we have enabled. Table 2 gives a brief explanation of these views, how you might use them, and some things to look out for.

select table_name
      ,sum(decode(column_name,'SID',1,'SESSION_ID',1,0))               SID
      ,sum(decode(column_name,'CLIENT_ID',1,'CLIENT_IDENTIFIER',1,0))  CLIENT_ID
      ,sum(decode(column_name,'SERVICE_NAME',1,0))                     SERVICE_NAME
      ,sum(decode(column_name,'ACTION',1,0))                           ACTION
      ,sum(decode(column_name,'MODULE',1,0))                           MODULE
      ,sum(decode(column_name,'SERIAL#',1,0))                          SERIAL#
from (select owner,table_name,column_name
        from dba_tab_columns
       where owner = 'SYS'
         and column_name in ('SID', 'SESSION_ID',
                             'CLIENT_ID', 'CLIENT_IDENTIFIER',
                             'SERVICE_NAME', 'ACTION', 'MODULE', 'SERIAL#'))
group by table_name
order by table_name
/

                                   CLIENT SERVICE
TABLE_NAME                     SID     ID    NAME ACTION MODULE SERIAL#
------------------------------ --- ------ ------- ------ ------ -------
DBA_HIST_ACTIVE_SESS_HISTORY     1      1       0      1      1       0
V_$ACTIVE_SESSION_HISTORY        1      1       0      1      1       0
V_$CLIENT_STATS                  0      1       0      0      0       0
V_$SERVICE_STATS                 0      0       1      0      0       0
V_$SERV_MOD_ACT_STATS            0      0       1      1      1       0

The use of these views is quite straightforward. You need only query them for the statistical aggregation you have set up through the DBMS_MONITOR package. The real difficulty lies in setting up those aggregations stepped through in earlier parts of this series. Next time we will get into the new reporting options available for traces in Oracle 10g.

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