Besides all that the jdbc based datamodel to my knowledge(correct me if
I am wrong) does not return all records at a time,
jdbc does neither, the datamodel does work with record sets
and should return one record at a time, jdbc only buffers records
depending on the driver.
Werner
Joshua Davis wrote:
What does em.createNativeQuery() have to do with query pagination? The
dialects handle this so you don't need to worry about the weird stuff
that ORACLE, MySQL, and SQL Server need. This is what you want:
http://www.hibernate.org/hib_docs/v3/reference/en/html/objectstate.html#objectstate-querying-executing-pagination
This stuff has been in Hibernate since 2.x.
*From:* Dave [mailto:[EMAIL PROTECTED]
*Sent:* Friday, September 09, 2005 10:19 PM
*To:* MyFaces Discussion
*Subject:* Re: dataTable - Millions of records
I am not sure if Hibernate support this. Right now
em.createNativeQuery() is not implemented.
*/David Haynes <[EMAIL PROTECTED]>/* wrote:
Most relational databases have the ability to return a sub-set
of the
entire result set.
SQL allows you to say something like 'WHERE rownum > skip AND
rownum <=
(skip+n)'.
Some databases use an alternate syntax to achieve the same result.
(e.g. MySQL uses 'OFFSET skip LIMIT n')
As Mike Kienenberger pointed out earlier today in his reply, the
dataTable tag supports this via the parameters 'first=skip
rows=n' and
those values (skip and n) can be made available to your backing
bean.
So, you can code the SQL query (in JDBC or Hibernate or
what-ever) to
honour the skip and n values.
-david-
Dave wrote:
>
> Does JDBC execute query return the whole set of records in
memory? do
> you mean data model in JDBC library? Thanks!
> */Werner Punz /* wrote:
>
> Dave wrote:
> ; > For a large database table that has millions of
records(rows),
> how is
> > the memory managed from backend to ? all the millions of
> > records are in memory? That would crash the system. Is the
> collection(
> > returned from database layer) actually not filled with data
> until they
> > are requested ? Thanks. Dave
> >
> implementing a custom datamodel might be your friend in this
case...
> unless you use plain jdbc, afair there was a jdbc datamodel
in the
> core classes.
>
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