Exception [type: SIGSEGV, Address not mapped to object]

Question

Hi,
I'm working on an Oracle Database 11g Release 11.1.0.6.0 - 64bit Production With the Real Application Clusters option.
I'm trying to execute the below:
      SELECT /*+ CURSOR_SHARING_EXACT */
             vc.id_vehicle, gr.geoRouteId, g.name, round(g.length) length_, gr.active,
             g.id_user id_user_georoute_owner, gr.grBindUserId id_user_bind_owner,
             (SELECT count(*) FROM dual WHERE XMLEXISTS('$XML_ALM/user/alarmwhen[@direction="out"]' passing gr.geoRouteUser AS "XML_ALM") = 1) alm_out
        FROM configurator.t_vehicle_configuration vc, dispatch.v_georoute g,
             xmltable('$XML/vehicleconf/GeoRoute/geoRoute[@active="1"]'
               passing vc.x_configuration AS "XML"
               columns geoRouteId   number  path '@id',
                       active       number  path '@active',
                       grBindUserId number  path '@id_user',
                       geoRouteUser xmltype path 'user'
             ) gr
       WHERE vc.id_vehicle = 453
         AND g.id_georoute = gr.geoRouteId;but after few seconds I got the error in the object.
The alert log says:
+Exception [type: SIGSEGV, Address not mapped to object] [ADDR:0x38] [PC:0x483CEFD, evahtr()+495]+
Errors in file /u01/app/oracle/diag/rdbms/evodb/EVODB2/trace/EVODB2_ora_13769.trc  (incident=301686):
+ORA-07445: exception encountered: core dump [evahtr()+495] [SIGSEGV] [ADDR:0x38] [PC:0x483CEFD] [Address not mapped to object] []+
Incident details in: /u01/app/oracle/diag/rdbms/evodb/EVODB2/incident/incdir_301686/EVODB2_ora_13769_i301686.trc
The trace doesn't say more:
+ORA-07445: exception encountered: core dump [evahtr()+495] [SIGSEGV] [ADDR:0x38] [PC:0x483CEFD] [Address not mapped to object] []+
+========= Dump for incident 301686 (ORA 7445 [evahtr()+495]) ========+
----- Beginning of Customized Incident Dump(s) -----
+Exception [type: SIGSEGV, Address not mapped to object] [ADDR:0x38] [PC:0x483CEFD, evahtr()+495]+
The strange stuff is that if I remove the
(SELECT count(*) FROM dual WHERE XMLEXISTS('$XML_ALM/user/alarmwhen[@direction="out"]' passing gr.geoRouteUser AS "XML_ALM") = 1) alm_out
from the query, there is no problem.
Do you have any suggestion?
Thanks in advance,
Samuel

Answer 1

The strange stuff is that if I remove the
(SELECT count(*) FROM dual WHERE XMLEXISTS('$XML_ALM/user/alarmwhen[@direction="out"]' passing gr.geoRouteUser AS "XML_ALM") = 1) alm_out
from the query, there is no problem.That's probably because you're not using XMLExists correctly.
The function returns a boolean value so you don't need to test for 1 or 0 as we had to with existsNode function before :
http://download.oracle.com/docs/cd/B28359_01/appdev.111/b28369/xdb04cre.htm#sthref360
It's also probably better to use a CASE expression instead of a subquery :
SELECT /*+ CURSOR_SHARING_EXACT */
       vc.id_vehicle
     , gr.geoRouteId
     , g.name
     , round(g.length) length_
     , gr.active
     , g.id_user id_user_georoute_owner
     , gr.grBindUserId id_user_bind_owner
     , case when XMLExists('$XML_ALM/user/alarmwhen[@direction="out"]' passing gr.geoRouteUser AS "XML_ALM")
            then 1
            else 0
       end as alm_out
FROM configurator.t_vehicle_configuration vc
   , dispatch.v_georoute g
   , xmltable('$XML/vehicleconf/GeoRoute/geoRoute[@active="1"]'
               passing vc.x_configuration AS "XML"
               columns geoRouteId   number  path '@id',
                       active       number  path '@active',
                       grBindUserId number  path '@id_user',
                       geoRouteUser xmltype path 'user'
     ) gr
WHERE vc.id_vehicle = 453
AND g.id_georoute = gr.geoRouteId
;Even better, you can test the condition directly in the COLUMNS clause with fn:exists XPath function.
For example, something like this :
SQL> with sample_data as (
  2    select xmltype('<root>
  3  <row><item>1</item><other id="a"/><other id="x"/></row>
  4  <row><item>2</item><other id="b"/></row>
  5  <row><item>3</item><other id="b"/></row>
  6  </root>') doc
  7    from dual
  8  )
  9  select x.*
10  from sample_data t
11     , xmltable(
12         '/root/row'
13         passing t.doc
14         columns item number path 'item',
15                 flag number path 'exists(other[@id="x"])'
16       ) x
17  ;
      ITEM       FLAG
         1          1
         2          0
         3          0