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From Ян Программист <webautoma...@gmail.com>
Subject Re: Data type compatibility
Date Tue, 30 Mar 2010 09:46:22 GMT
>
> I think you are describing an approximate numeric data type, in which
> two distinct values would be considered to be equal if the difference
> between them was small. So sometimes when manipulating a value we would
> pay attention to the entire precision, sometimes we would not.
>
> Is that right?
>
You are right. Besides usually precision is lost on the client side, while
data is processed in formulas after retrieval. Because it is a part of
metrology theory to figure out minimal precision loss due formula
calculations. As a result it would be a good perspective to use Derby in
embed, real time Java systems. So there is a good chance to balance
client/storage performance in such a precision driven way

>
>    2. XML type compatibility
>>
>
> I didn't understand this proposal. Derby currently supports an XML
> data type; it is described here:
> http://db.apache.org/derby/docs/10.5/ref/rrefsqljtypexml.html
>
> "Because none of the JDBC-side support for SQL/XML is implemented in Derby,
it is not possible to bind directly into an XML value or to retrieve an XML
value directly from a result set using JDBC. Instead, you must bind and
retrieve the XML data as Java strings or character streams by explicitly
specifying the appropriate XML operators, XMLPARSE and XMLSERIALIZE, as part
of your SQL queries"

But if XML values would be retrievable from indexed only columns
(non-indexed data would not be critical to retrieve; rather would be
retrieved in other client and/or way)... so I was meaning that client
connector would support XML. But you would not have overloads to Derby doing
XMLPARSE/XMLSERIALIZE - Derby engine would feel like it is processing normal
SQL queries

> Do you feel that this data type is not compatible with Oracle or DB2?
>
I remember that, at least, SQL Server has direct XML support, with binding
or something like that. Tell me what support in SQL you see minimal. Besides
customizability level in those databases comes to the skies ;), unlike Derby
for existing XML support ;=(

John






>
> thanks,
>
> bryan
>
>

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