Large XML and DBMS_XMLSTORE

Question

Oracle DB = 10.2.0.3
I have XML messages (size range 300KB - 15MB) that are inserted into a table with an XMLType column throughout the day.
The volume will vary...say 10 transactions per minute. A single transaction can contain any number of entities/objects.
I have no need to preserve the XML - aside from assigning it a sequence number, date etc. and storing it for debugging (if needed).
Currently, I have a trigger defined on the table that calls various database packages
that shred the data via XMLTable (i.e. insert into tab1...select...xmltable..).
The problem is that I potentially need to insert into 50+ tables out of 200+ tables per transaction. So, I'm passing through the single instance document 200+ times.
The number of tables that are needed to represent the XML will continue to grow.
A 300KB XML message takes approx 10 seconds to shred. Obviously, I'm concerned about the larger messages.
     So, I was wondering if doing the following would be any better:
1. Have a XSLT transform the original message into "pseudo" Oracle canonical format.
At this point, all of the data contained in the message would need to be shredded and all unwanted data from the original message would be filtered..i.e. lowering the message size a little.
The message to be inserted would then look something like this:
<Transaction>
     <Table>
     <Name>TAB1</Name>
     <ROWSET>
          <ROW>
          <COL1>
          <COLn>
          </ROW>
</ROWSET>
</Table>
     <Table>
     <Name>TAB2</Name>
     <ROWSET>
          <ROW>
          <COL1>
          <COLn>
          </ROW>
</ROWSET>
</Table>
</Transaction>
2. Next, define a trigger on the table like this:
CREATE OR REPLACE TRIGGER tr_ai_my_table
AFTER INSERT
ON my_table
FOR EACH ROW
DECLARE
CURSOR table_cur
IS
SELECT a.table_nm
,a.xml_fragment
FROM XMLTABLE ('/Transaction/Table[Name]'
PASSING :NEW.xml_document
COLUMNS
table_nm VARCHAR2(30) PATH 'Name'
,xml_fragment XMLTYPE PATH 'ROWSET'
) a;
v_context DBMS_XMLSTORE.ctxtype;
v_rows NUMBER;
-- XML Date format: 2007-08-02
-- XML Datetime format: 2007-08-02T11:58:28.229-04:00
-- ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD';
-- ALTER SESSION SET NLS_TIMESTAMP_FORMAT = 'YYYY-MM-DD-HH24.MI.SS.FF';
-- ALTER SESSION SET NLS_TIMESTAMP_TZ_FORMAT = 'YYYY-MM-DD"T"HH24:MI:SS.FFTZH:TZM';
BEGIN
FOR table_rec IN table_cur
LOOP
v_context := DBMS_XMLSTORE.newcontext (table_rec.table_nm);
v_rows := DBMS_XMLSTORE.insertxml (v_context, table_rec.xml_fragment);
DBMS_XMLSTORE.closecontext (v_context);
END LOOP;
END;
     I know this will get me out of maintaining 200+ insert statements/xpaths. Also, I wouldn't be coding the XSLT either and the XSLT may end up running on some specialized hardware for optimized performance.
But do I gain a significant performance boost using the Oracle canonical format
and DBMS_XMLSTORE even though I'm still building the DOM tree to build the cursor ?

Answer 1

i saw a problem with the xmlbeans implementation with wli 8.1
we had memeory issues with large xmls messages as they seemded to be in memory even through the JPD had finished.
to solve this we inserted code at the end of a process to assign the top level xmlbean document class to a tiny version of the same message type. this is valid when the document object is a top level variable of the jpd.
this was done to stop xmlbeans caching the large message behind the scenes.