Re: faster way to create XML export
Date: Tue, 2 Aug 2011 20:27:42 -0500
Message-ID: <CA+fnDAaoH8q-0YHDJUr5fUo+uAUZFd+XuwaSp=NWbquGVRKnQw_at_mail.gmail.com>
Any idea how to add the XSLT header with XMLGEN, similar to java xmlQuery.setStylesheetHeader()? We can't figure it out.
We need output like this at the top of the file: <?xml-stylesheet href="http://some_xml.xslt" type="text/xsl"?>
-J
On Tue, Aug 2, 2011 at 8:10 PM, Marco Gralike <Marco.Gralike_at_amis.nl> wrote:
> Ah, I see you have found it :-) (the C bit contra Java wrapper bit)
>
> From: Jeremy Schneider <jeremy.schneider_at_ardentperf.com>
> Date: Wed, 3 Aug 2011 02:43:36 +0200
>
> To: Marco Gralike <marco.gralike_at_amis.nl>
> Cc: Oracle-L <oracle-l_at_freelists.org>
> Subject: Re: faster way to create XML export
>
> We just finished a test run with DBMS_XMLGEN on the same dataset -- it
> finished in 2 sec. Still used dbms_xslprocessor.clob2file for filewriting.
> Looks like this will do most everything I mentioned - just working on the
> last step now, getting the XSLT headers. (Seems to be a function for this
> but it's not well documented and didn't seem to work on our first try...)
>
> Also, I noticed something in the oracle docs here:
>
> http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14252/adx_j_xsu.htm#sthref546
>
> "Note: For increased performance, consider using DBMS_XMLGen and
> DBMS_XMLStore as alternatives to DBMS_XMLQuery and DBMS_XMLSave. The former
> packages are written in C and are built in to the database kernel. You can
> also use SQL/XML functions such as XML_Element for XML access in the
> database."
>
> No kidding - way faster! Wish I'd seen this before! :)
>
> -Jeremy
>
> On Tue, Aug 2, 2011 at 6:34 PM, Jeremy Schneider <
> jeremy.schneider_at_ardentperf.com> wrote:
>
>> Oh yeah, we also tested with the DBMS_XMLQuery package - it seemed to take
>> about as long as the Oracle Serializer java code.
>>
>>
>> On Tue, Aug 2, 2011 at 6:19 PM, Jeremy Schneider <
>> jeremy.schneider_at_ardentperf.com> wrote:
>>
>>> Well we're not making any 1GB files yet, but I can't really imagine what
>>> anyone does with a 400MB file either. Anyway - we were doing some testing
>>> with a much smaller "test" dataset (8MB file), and we tried Marco's idea.
>>> Here are the results:
>>>
>>> Original Code: 96 sec
>>> Oracle Serializer: 40 sec
>>> Marco's Code: 3 sec
>>>
>>> :)
>>>
>>> Sweet! However, it seems that there's an implicit conversion from
>>> XMLType to CLOB and it's not immediately obvious how to control the XML
>>> that's generated. I guess it's time for me to learn some more about XMLDB.
>>> :-/ Here's what we're trying to figure out how to do with XMLType:
>>>
>>> - xmlQuery.keepCursorState(true);
>>> - xmlQuery.setMaxRows(pRowLimit_variable); // Note: we continue with
>>> cursor and split output to multiple files
>>> - xmlQuery.setRowTag(pRowHeader_variable);
>>> - xmlQuery.setRowsetTag(pRowHeader_variable+"_MYSUFFIX");
>>> - xmlQuery.setDateFormat("yyyy-MM-dd'T'HH:mm:ss");
>>> - xmlQuery.setStylesheetHeader(pXSLtURI_variable);
>>>
>>> Any tips would be appreciated...
>>>
>>> -J
>>>
>>>
>>> PS - this blog post by Marco is excellent:
>>> http://www.liberidu.com/blog/?p=369
>>>
>>>
>>> On Tue, Aug 2, 2011 at 4:41 PM, Marco Gralike <Marco.Gralike_at_amis.nl>wrote:
>>>
>>>> ONE 1++GB in XML document, are you serious.
>>>> Wouldn't be surprised though. I see it more and more often. ;-)
>>>>
>>>> No the stuff showed below is in C and/or even part of the C kernel. It
>>>> is possible to do in SQL and yes due to the fact that it is 1 XML document
>>>> you will get in trouble regarding those mentioned sizes per XML document. I
>>>> am guessing, although never really checked that if you switched it again for
>>>> a C based SAV serializer it would be even faster or does it reside in the
>>>> JVM database kernel?
>>>>
>>>> I wonder which part picks up those big XML documents and tries to do
>>>> something useful with it. Work to be done with those documents afterwards
>>>> most be very resource intensive ;-)
>>>>
>>>
>>
>>
>
-- http://www.ardentperf.com +1 312-725-9249 Jeremy Schneider Chicago -- http://www.freelists.org/webpage/oracle-lReceived on Tue Aug 02 2011 - 20:27:42 CDT