Question

We have an internal application based on .Net which calls certain procedures in Oracle (10g). One of these queries is run to get in/out parameters of these procedures. It’s a pretty simple select query. But even under the best of circumstances, it is taking 3 seconds. At lease few times a day it starts taking more than 40 seconds and causes our .Net application to time out.

Select query is:

SELECT   a.argument_name,
           a.data_type,
           a.in_out,
           NVL (a.data_length, 0) AS data_length,
           NVL (a.data_precision, 0) AS data_precision,
           NVL (a.data_scale, 0) AS data_scale
    FROM   ALL_ARGUMENTS a, all_objects o
   WHERE   o.object_id =
              (SELECT   object_id
                 FROM   all_objects
                WHERE       UPPER (object_name) = UPPER ('resourcemanager_pkg')
                        AND object_type = 'PACKAGE'
                        AND owner = 'OFFICEDBA')
           AND UPPER (a.object_name) = UPPER ('p_search_roles')
           AND a.OBJECT_ID = o.OBJECT_ID
ORDER BY   a.position ASC

This query returns the in/out parameters of particular procedure.

resourcemanager_pkg is package name, p_search_roles is procedure name.
We call this query for every database call for procedures.

Is there anything which is wrong with this query?

Answer 1

Do you have the ability to modify the query that is being generated? It appears that it is doing an extraneous join to the ALL_OBJECTS table. It appears that your query is equivalent to this

SELECT   a.argument_name,
           a.data_type,
           a.in_out,
           NVL (a.data_length, 0) AS data_length,
           NVL (a.data_precision, 0) AS data_precision,
           NVL (a.data_scale, 0) AS data_scale
    FROM   ALL_ARGUMENTS a,
           (SELECT   object_id
              FROM   all_objects
             WHERE       UPPER (object_name) = UPPER ('resourcemanager_pkg')
                     AND object_type = 'PACKAGE'
                     AND owner = 'OFFICEDBA') o
    WHERE  UPPER (a.object_name) = UPPER ('p_search_roles')
      AND  a.OBJECT_ID = o.OBJECT_ID
    ORDER  BY a.position ASC

I would also expect that using ALL_PROCEDURES rather than ALL_OBJECTS to get the OBJECT_ID would be more efficient.

Have you gathered dictionary statistics? Queries against the data dictionary views are generally rather hard to tune since you can’t add indexes or other structures to speed things up. But at least gathering dictionary statistics may give the optimizer better information to be able to pick a better plan.

Finally, is it possible that you could materialize the data from the data dictionary in a materialized view that refreshes periodically that you could index? That would mean that the results wouldn’t immediately reflect changes to the definition of procedures. On the other hand, you don’t generally want to be making changes to procedure definitions live and you can always refresh the materialized views after making schema changes.