RE: storing xml files into database

[Chris Parkerson <chrisp@exceloncorp.com>]

Frank:

How long has it been since you looked at XIS?  We have X/A transaction
support, online backup and restore, support failover and fault tolerant
configurations, and replication if necessary (although rarely necessary
in XIS's distributed caching model).  We have all the features you'd
expect from any other database, except for the ones that really aren't
needed.  But, then again, we're not competing against Oracle: we bring
benefit on the XML side of things where Oracle fails (and we've proven
it fails) and let our customers keep the enterprise systems that they
trust to do what they trust them for.

There have been several attempts at optimizing a relational model for
dealing with XML.  To date, I have not seen it work.  Like I said
earlier, I have not been able to get a hold of a copy of B-Bop to really
try it and see if it works and if it can scale and perform to the levels
we've seen with our own XIS.  In theory, our approach should be more
efficient and better, but I'd rather prove the theory if only given the
opportunity.

Cheers,
Chris

---------------------------------------
Chris Parkerson
Product Manager
eXcelon Corporation
Burlington, MA
(781) 674-5393
http://www.exceloncorp.com
---------------------------------------


-----Original Message-----
From: Frank Richards [mailto:frichards@softquad.com] 
Sent: Monday, September 10, 2001 2:06 PM
To: Bill Lindsey; xml-dev@lists.xml.org
Subject: RE: storing xml files into database

If you (B-Bop) have this running, I really recommend some technical
marketing -- whitepapers and conference talks.
With my Softquad hat on I can tell you that the CMS market has
frustrated
us: The OODBMS based ones haven't scaled well
because Poet and Excelon (the DBMSs) just don't have all the big system
features of Oracle and DB2 -- Astoria and Poet were fine departmental
solutions --, while the relational based ones start painful, but don't
get
any worse as you go from a department to the Fortune 500.

Frank

-----Original Message-----
From: Bill Lindsey [mailto:bill@blnz.com]
Sent: Monday, September 10, 2001 1:08 PM
To: xml-dev@lists.xml.org
Subject: Re: storing xml files into database


Frank Richards wrote:
> XML is a tree of elements. Naively mapping that tree onto a table
causes
the
> RDBMS to
> thrash it's guts out doing joins to go down the tree --
[ ... ]
> XML in an
> RDBMS can easily hit six or seven joins per query.

A typical, naive definition of a "nodes" table does lead to unacceptable
performance due to the necessity of many self-joins.  It is possible,
however, to devise a scheme for encoding nodes' context in a compact
form, optimized for an RDBMS' indexing facility, and build a
generic table structure, capable of storing any well-formed
XML, yet does not exhibit the self-join problem.

With this technique, one can:
* leverage the mature ACID properties of commercial RDBMSs
* support any well formed XML with no additional developer or DBA effort
* provide fine-grained, random access to the content of large
collections
* efficiently query on content and/or structure

Bill Lindsey
B-Bop

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