APEX 'crawling' whilst executing a query using CONNECT BY

Question

Hi Folks.
Anyone seen this behaviour before?
I can run this SQL (with the appropriate page item values substitued) in PL/SQL developer and I get the result in less than 0.094 seconds with a COST of 13
SELECT NULL LINK
      ,a.data_points
      ,5000 forecast_value
FROM
(SELECT to_char(trunc(add_months((SELECT iag.agreement_start_date
                                FROM   iot_agreement iag
                                WHERE  iag.iot_agreement_id =
                                       :P317_IOT_REBATE_AGREEMENT_ID)
                               ,LEVEL - 1)
                    ,'mm')
              ,'MON-RR') data_points
FROM   dual
CONNECT BY LEVEL <=
           trunc(months_between((SELECT iag.agreement_end_date
                                FROM   iot_agreement iag
                                WHERE  iag.iot_agreement_id =
                                       :P317_IOT_REBATE_AGREEMENT_ID)
                               ,(SELECT iag.agreement_start_date
                                FROM   iot_agreement iag
                                WHERE  iag.iot_agreement_id =
                                       :P317_IOT_REBATE_AGREEMENT_ID)))
MINUS
SELECT pkg_ngc_utilities.get_long_traffic_month(imps.traffic_period_id)
FROM   iot_mfs_plus_summary imps
WHERE  imps.client_master_entity_id = :P317_CLIENT_MASTER_ENTITY_ID
AND    imps.home_master_entity_id IN
       (SELECT ipy.master_entity_id
         FROM   iot_party ipy
         WHERE  ipy.iot_agreement_id = :P317_IOT_REBATE_AGREEMENT_ID
         AND    ipy.client_side = 0) -- Roaming Partner
AND    imps.visited_master_entity_id = imps.client_master_entity_id
AND    pkg_ngc_utilities.get_long_traffic_month(imps.traffic_period_id) IN
       (SELECT to_char(trunc(add_months((SELECT iag.agreement_start_date
                                            FROM   iot_agreement iag
                                            WHERE  iag.iot_agreement_id =
                                                   :P317_IOT_REBATE_AGREEMENT_ID)
                                        ,LEVEL - 1)
                             ,'mm')
                       ,'MON-RR') data_points
         FROM   dual
         CONNECT BY LEVEL <= trunc(months_between ((SELECT iag.agreement_end_date
                                    FROM   iot_agreement iag
                                    WHERE  iag.iot_agreement_id =
                                           :P317_IOT_REBATE_AGREEMENT_ID) ,
                                      (SELECT iag.agreement_start_date
                                            FROM   iot_agreement iag
                                            WHERE  iag.iot_agreement_id =
                                                   :P317_IOT_REBATE_AGREEMENT_ID)
                                    )))) a
ORDER BY to_date(a.data_points, 'MON-RR')If I use the same query in a Flash Chart the page still only takes a few seconds to display but the chart takes over a minute to display. APEX ADMIN shows the page being served in 2 - 3 seconds.
If I drop the chart and drop the query into a simple report region, the entire page takes over a minute to display.
Has anyone experienced anything similar?
This is the first time I have used CONNECT BY LEVEL in my SQL so that is my main suspect. But please remember, in SQL/Developer the query executes very quickly indeed.
Many thanks
Kind regards
Simon Gadd

Answer 1

Hi Simon,
I had something similar. When my code ran is SQL is took seconds, but took minutes in an ApEx page. There seems to the something strange with the way ApEx and/or the optimizer execute code via ApEx pages.
I gave my code to one of my tuning experts and they added a simple rule to force index use:
select  /*+RULE index(r AMS_REQUESTS_IDX4) */
        r.requester_name,
        r.ams_type_code_name,
        d.display_date
from
        (select TO_DATE(:P23_CALENDAR_DATE,'YYYYMMDD')-100+rownum display_date from all_objects where rownum < 300) d,
        ams_requests_v r
where
        trunc(d.display_date) between trunc(r.start_date) and trunc(r.end_date)
and        r.approval_status != 'R'       
and        to_char(d.display_date,'DY') NOT IN ('SAT','SUN')
and     d.display_date not in (select trunc(closure_date) from ams_closures)
and        (nvl(r.restricted_view_flag,'N') = 'N' or trunc(r.end_date) >= trunc(sysdate))
and     r.department_id in (        select
                                        d.department_id
                                from
                                        ams_departments d
                                connect by ( PRIOR DEPARTMENT_ID = PARENT_DEPARTMENT_ID)
                                start with department_id = (
                                                                select
                                                                        department_id
                                                                from
                                                                        ams_departments
                                                                where
                                                                        nvl(terminating_dept_flag,'N') = 'Y'
                                                                and         level = (select
                                                                                        min(level)                                                       
                                                                                 from
                                                                                        ams_departments
                                                                                where
                                                                                        nvl(terminating_dept_flag,'N') = 'Y'
                                                                                        connect by department_id = prior parent_department_id
                                                                                        start with department_id = :P0_DEPARTMENT_ID)
                                                                connect by department_id = prior parent_department_id
                                                                start with department_id = :P0_DEPARTMENT_ID))        
UNION
select  /*+RULE index(r AMS_REQUESTS_IDX4) */
        r.requester_name,
        r.ams_type_code_name,
        d.display_date
from
        (select TO_DATE(:P23_CALENDAR_DATE,'YYYYMMDD')-100+rownum display_date from all_objects where rownum < 300) d,
        ams_requests_v r
where
        trunc(d.display_date) between trunc(r.start_date) and trunc(r.end_date)
and        r.approval_status != 'R'       
and     to_char(d.display_date,'DY') NOT IN ('SAT','SUN')
and     d.display_date not in (select trunc(closure_date) from ams_closures)
and     nvl(r.restricted_view_flag,'N') = 'Y'
and     r.department_id in (        select distinct
                                        d.department_id
                                from
                                        ams_departments d
                                connect by ( PRIOR DEPARTMENT_ID = PARENT_DEPARTMENT_ID)
                                start with department_id in (
                                                                select
                                                                        department_id
                                                                from
                                                                        ams_departments_v
                                                                where
                                                                        :P0_PERSON_ID in (manager_id, deputy_id,administrator_id)))       
UNION
select
        NULL                              requester_name,
        t.name                            ams_type_code_name,
        trunc(c.closure_date)             display_date
from
        ams_closures c,
        ams_closure_type_codes_v t
where
        c.AMS_CLOSURE_TYPE_CODE = t.AMS_CLOSURE_TYPE_CODE   
order by 3,1It might be worth you trying something similar.
best regards,
Martin