732RE: [xml-dbms] Re: UPDATE & DELETE
- Mar 2, 2001The issue is running out of keys not collisions on the table. After doing
some simple aritmetic, I decided it's not a big enough issue to worry too
much about (except my clients may balk.) If worse comes to worst, then
writing our own key generator seems like a workable alternative.
Thanks for responding so quickly,
From: Ronald Bourret [mailto:rpbourret@...]
Sent: Friday, March 02, 2001 2:03 PM
Subject: Re: [xml-dbms] Re: UPDATE & DELETE
Robin Fried wrote:
>The code uses an int (32 bits). Assuming the JDBC driver does the
> Concerning the "Generate" capability, how will XML-DMBS behave if the
> XMLDBMSKEY.HighKey is defined as a 64bit entity (e.g., bigint in SQL
> Server)? In other words, does the underlying key grabber code in java
> assume it's a 32bit int or a long int (64bits)?
conversion correctly (the code calls ResultSet.getInt()), it looks like
the code should work. However, I haven't actually tried it.
> If the latter, then itIs your worry about scalability due to multiple concurrent hits on the
> should just work automatically. Looks like the code assume integer. The
> problem is that all tables are sharing the same key generator, which
> distributes the set of all possible keys across the entire database -- not
> very scalable!
XMLDBMSKey table or on running out of key values? The former shouldn't
be a problem, since each hit on the table can be used to generate 256
key values. If it is the latter, you are correct, since the theoretical
limit of key values is about 4 billion and the practical limit is much
smaller -- somewhere around 16-100 million, depending on the XML
documents you insert.
There are two solutions here. First, you can write your own key
generation routine (implement the KeyGenerator interface) and pass it to
DOMToDBMS. Second, I've considered modifying the map document so you can
specify a different key generator for each table. However, I can't
remember anybody ever asking for the latter, so it is very low priority.
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