XMLDOM.appendChild performance

Question

Hi All,
I have a large xml (52,000 messages under the root element). There's about 5 elements under each Message element. Parsing each element takes about 2 minutes which is great. However, when I try to add two more elements under the message element using XMLDOM.appendChild , the execution time goes up to 11 minutes.
DB Version: Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit
Any ideas on how to make it run faster?
Is there an issue with XMLDOM.appendChild

Answer 1

Hi,
Any ideas on how to make it run faster?
Is there an issue with XMLDOM.appendChildActually, there's an issue with the whole approach.
Given your db version, you should stop using DOM and start using binary XMLType and related functionalities.
Could you describe a little bit more what you want to do? A sample data with expected output would help.
- What does "parsing" mean to you? Extracting XML data into variables or columns?
- Do you want to add two more elements under each of the 52000 Messages?
Here's a glimpse of what you can do :
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> create table tmp_xml of xmltype;
Table created.Creating a sample document with 10000 messages...
SQL> set timing on
SQL> insert into tmp_xml
  2  select xmlelement("root",
  3           xmlagg(
  4             xmlelement("message",
  5               xmlforest(
  6                 'A'||to_char(level, 'fm09999') as "item1"
  7               , 'B'||to_char(level, 'fm09999') as "item2"
  8               , 'C'||to_char(level, 'fm09999') as "item3"
  9               , 'D'||to_char(level, 'fm09999') as "item4"
10               , 'E'||to_char(level, 'fm09999') as "item5"
11               )
12             )
13           )
14         )
15  from dual
16  connect by level <= 10000 ;
1 row created.
Elapsed: 00:00:00.56
SQL>Parsing into a relational structure...
SQL> select x.*
  2  from tmp_xml t
  3     , xmltable(
  4         '/root/message'
  5         passing t.object_value
  6         columns item1 varchar2(6) path 'item1'
  7               , item2 varchar2(6) path 'item2'
  8               , item3 varchar2(6) path 'item3'
  9               , item4 varchar2(6) path 'item4'
10               , item5 varchar2(6) path 'item5'
11       ) x
12  where rownum <= 10 ;
ITEM1  ITEM2  ITEM3  ITEM4  ITEM5
A00001 B00001 C00001 D00001 E00001
A00002 B00002 C00002 D00002 E00002
A00003 B00003 C00003 D00003 E00003
A00004 B00004 C00004 D00004 E00004
A00005 B00005 C00005 D00005 E00005
A00006 B00006 C00006 D00006 E00006
A00007 B00007 C00007 D00007 E00007
A00008 B00008 C00008 D00008 E00008
A00009 B00009 C00009 D00009 E00009
A00010 B00010 C00010 D00010 E00010
10 rows selected.
Elapsed: 00:00:00.37
SQL>Appending two more children to each message using XQuery Update (11.2.0.3 only) :
SQL> update tmp_xml t
  2  set t.object_value =
  3         xmlquery(
  4           'copy $d := .
  5            modify (
  6              for $i in $d/root/message
  7              return insert node $e into $i
  8            )
  9            return $d'
10          passing t.object_value
11               ,  xmlconcat(
12                    xmlelement("item6")
13                  , xmlelement("item7")
14                  ) as "e"
15          returning content
16         )
17  ;
1 row updated.
Elapsed: 00:00:04.25
SQL>
SQL> set long 500
SQL> set pages 100
SQL> select object_value from tmp_xml ;
OBJECT_VALUE
<root>
  <message>
    <item1>A00001</item1>
    <item2>B00001</item2>
    <item3>C00001</item3>
    <item4>D00001</item4>
    <item5>E00001</item5>
    <item6/>
    <item7/>
  </message>
  <message>
    <item1>A00002</item1>
    <item2>B00002</item2>
    <item3>C00002</item3>
    <item4>D00002</item4>
    <item5>E00002</item5>
    <item6/>
    <item7/>
  </message>
  <message>
    <item1>A00003</item1>
    <item2>B00003</item2>
    <item3>C00003</item3>
    <item4>D00003</item4>
    <item5>E000
Elapsed: 00:00:00.14Edited by: odie_63 on 7 janv. 2013 00:12