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Posted to ojb-user@db.apache.org by Jamo Smith <ja...@gmail.com> on 2005/02/19 23:31:05 UTC
Using a TreeSet, or other SortedSet
I have a one to many relationship. I need to retrieve the many in a
SortedSet as optimally as possible(instead of retrieving as a
collection then adding to a TreeSet) What is the way to do this with
OJB?
--
Jamo Smith
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Re: Using a TreeSet, or other SortedSet
Posted by Jakob Braeuchi <jb...@gmx.ch>.
hi jamo,
Jamo Smith schrieb:
> What if i modifed an element of the collection while, it was in the
> cache, would it be resorted the next time I retrieve it? I think with
> the SQL sort it would only be sorted when it was refreshed from the
> database, which should be minimized.
yes you'll have to refresh the collection in this case.
>
> The use of this is in a forum where there may be a large # of topics
> that need to be sorted by topic type & by topic lastupdated. I do
> have a start & end index and usually it is only a pull of 20-30
> topics. Could this be done a better way?
i think it depends on how often the data is updated. don't need to go to
the database to get the last updated topic ?
when using the start- and end-index in ojb you'l have to be aware of the
fact that ojb handles these indices internally, not in the sql.
jakob
>
> Thank you very much for your help!
>
> On Sun, 20 Feb 2005 19:28:26 +0100, Jakob Braeuchi <jb...@gmx.ch> wrote:
>
>>hi jamo,
>>
>>afaik ojb supports a single column only in the collection-descriptor.
>>for more flexibility you could also use a query-customizer.
>>i think sorting the rows using sql is more effective than using compareTo.
>>
>>jakob
>>
>>Jamo Smith schrieb:
>>
>>>My object is sorted by more than one column. It is best, I think, to
>>>utilize compareTo in this instance. More important, would the below
>>>method be as optimal as the method I purpose - if so, could I have it
>>>sort by multiple columns?
>>>
>>>
>>>On Sun, 20 Feb 2005 17:24:31 +0100, Jakob Braeuchi <jb...@gmx.ch> wrote:
>>>
>>>
>>>>hi jamo,
>>>>
>>>>the collecton descriptor supports sorting. ie:
>>>>
>>>> <collection-descriptor
>>>> name="allArticlesInGroup"
>>>> element-class-ref="org.apache.ojb.broker.AbstractArticle"
>>>> auto-retrieve="true"
>>>> auto-update="true"
>>>> auto-delete="false"
>>>> >
>>>> <orderby name="articleId" sort="DESC"/>
>>>> <inverse-foreignkey field-ref="productGroupId" />
>>>> </collection-descriptor>
>>>>
>>>>hth
>>>>jakob
>>>>
>>>>Jamo Smith schrieb:
>>>>
>>>>
>>>>>I have a one to many relationship. I need to retrieve the many in a
>>>>>SortedSet as optimally as possible(instead of retrieving as a
>>>>>collection then adding to a TreeSet) What is the way to do this with
>>>>>OJB?
>>>>>
>>>>>--
>>>>>Jamo Smith
>>>>>
>>>>>---------------------------------------------------------------------
>>>>>To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
>>>>>For additional commands, e-mail: ojb-user-help@db.apache.org
>>>>>
>>>>>
>>>>
>>>>---------------------------------------------------------------------
>>>>To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
>>>>For additional commands, e-mail: ojb-user-help@db.apache.org
>>>>
>>>>
>>>
>>>
>>>
>>---------------------------------------------------------------------
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>>For additional commands, e-mail: ojb-user-help@db.apache.org
>>
>>
>
>
>
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Re: Using a TreeSet, or other SortedSet
Posted by Jamo Smith <ja...@gmail.com>.
What if i modifed an element of the collection while, it was in the
cache, would it be resorted the next time I retrieve it? I think with
the SQL sort it would only be sorted when it was refreshed from the
database, which should be minimized.
The use of this is in a forum where there may be a large # of topics
that need to be sorted by topic type & by topic lastupdated. I do
have a start & end index and usually it is only a pull of 20-30
topics. Could this be done a better way?
Thank you very much for your help!
On Sun, 20 Feb 2005 19:28:26 +0100, Jakob Braeuchi <jb...@gmx.ch> wrote:
> hi jamo,
>
> afaik ojb supports a single column only in the collection-descriptor.
> for more flexibility you could also use a query-customizer.
> i think sorting the rows using sql is more effective than using compareTo.
>
> jakob
>
> Jamo Smith schrieb:
> > My object is sorted by more than one column. It is best, I think, to
> > utilize compareTo in this instance. More important, would the below
> > method be as optimal as the method I purpose - if so, could I have it
> > sort by multiple columns?
> >
> >
> > On Sun, 20 Feb 2005 17:24:31 +0100, Jakob Braeuchi <jb...@gmx.ch> wrote:
> >
> >>hi jamo,
> >>
> >>the collecton descriptor supports sorting. ie:
> >>
> >> <collection-descriptor
> >> name="allArticlesInGroup"
> >> element-class-ref="org.apache.ojb.broker.AbstractArticle"
> >> auto-retrieve="true"
> >> auto-update="true"
> >> auto-delete="false"
> >> >
> >> <orderby name="articleId" sort="DESC"/>
> >> <inverse-foreignkey field-ref="productGroupId" />
> >> </collection-descriptor>
> >>
> >>hth
> >>jakob
> >>
> >>Jamo Smith schrieb:
> >>
> >>>I have a one to many relationship. I need to retrieve the many in a
> >>>SortedSet as optimally as possible(instead of retrieving as a
> >>>collection then adding to a TreeSet) What is the way to do this with
> >>>OJB?
> >>>
> >>>--
> >>>Jamo Smith
> >>>
> >>>---------------------------------------------------------------------
> >>>To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> >>>For additional commands, e-mail: ojb-user-help@db.apache.org
> >>>
> >>>
> >>
> >>---------------------------------------------------------------------
> >>To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> >>For additional commands, e-mail: ojb-user-help@db.apache.org
> >>
> >>
> >
> >
> >
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> For additional commands, e-mail: ojb-user-help@db.apache.org
>
>
--
Jamo Smith
---------------------------------------------------------------------
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Re: Using a TreeSet, or other SortedSet
Posted by Jakob Braeuchi <jb...@gmx.ch>.
hi jamo,
afaik ojb supports a single column only in the collection-descriptor.
for more flexibility you could also use a query-customizer.
i think sorting the rows using sql is more effective than using compareTo.
jakob
Jamo Smith schrieb:
> My object is sorted by more than one column. It is best, I think, to
> utilize compareTo in this instance. More important, would the below
> method be as optimal as the method I purpose - if so, could I have it
> sort by multiple columns?
>
>
> On Sun, 20 Feb 2005 17:24:31 +0100, Jakob Braeuchi <jb...@gmx.ch> wrote:
>
>>hi jamo,
>>
>>the collecton descriptor supports sorting. ie:
>>
>> <collection-descriptor
>> name="allArticlesInGroup"
>> element-class-ref="org.apache.ojb.broker.AbstractArticle"
>> auto-retrieve="true"
>> auto-update="true"
>> auto-delete="false"
>> >
>> <orderby name="articleId" sort="DESC"/>
>> <inverse-foreignkey field-ref="productGroupId" />
>> </collection-descriptor>
>>
>>hth
>>jakob
>>
>>Jamo Smith schrieb:
>>
>>>I have a one to many relationship. I need to retrieve the many in a
>>>SortedSet as optimally as possible(instead of retrieving as a
>>>collection then adding to a TreeSet) What is the way to do this with
>>>OJB?
>>>
>>>--
>>>Jamo Smith
>>>
>>>---------------------------------------------------------------------
>>>To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
>>>For additional commands, e-mail: ojb-user-help@db.apache.org
>>>
>>>
>>
>>---------------------------------------------------------------------
>>To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
>>For additional commands, e-mail: ojb-user-help@db.apache.org
>>
>>
>
>
>
---------------------------------------------------------------------
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Re: Using a TreeSet, or other SortedSet
Posted by Jamo Smith <ja...@gmail.com>.
My object is sorted by more than one column. It is best, I think, to
utilize compareTo in this instance. More important, would the below
method be as optimal as the method I purpose - if so, could I have it
sort by multiple columns?
On Sun, 20 Feb 2005 17:24:31 +0100, Jakob Braeuchi <jb...@gmx.ch> wrote:
> hi jamo,
>
> the collecton descriptor supports sorting. ie:
>
> <collection-descriptor
> name="allArticlesInGroup"
> element-class-ref="org.apache.ojb.broker.AbstractArticle"
> auto-retrieve="true"
> auto-update="true"
> auto-delete="false"
> >
> <orderby name="articleId" sort="DESC"/>
> <inverse-foreignkey field-ref="productGroupId" />
> </collection-descriptor>
>
> hth
> jakob
>
> Jamo Smith schrieb:
> > I have a one to many relationship. I need to retrieve the many in a
> > SortedSet as optimally as possible(instead of retrieving as a
> > collection then adding to a TreeSet) What is the way to do this with
> > OJB?
> >
> > --
> > Jamo Smith
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> > For additional commands, e-mail: ojb-user-help@db.apache.org
> >
> >
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> For additional commands, e-mail: ojb-user-help@db.apache.org
>
>
--
Jamo Smith
---------------------------------------------------------------------
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Re: Using a TreeSet, or other SortedSet
Posted by Jakob Braeuchi <jb...@gmx.ch>.
hi jamo,
the collecton descriptor supports sorting. ie:
<collection-descriptor
name="allArticlesInGroup"
element-class-ref="org.apache.ojb.broker.AbstractArticle"
auto-retrieve="true"
auto-update="true"
auto-delete="false"
>
<orderby name="articleId" sort="DESC"/>
<inverse-foreignkey field-ref="productGroupId" />
</collection-descriptor>
hth
jakob
Jamo Smith schrieb:
> I have a one to many relationship. I need to retrieve the many in a
> SortedSet as optimally as possible(instead of retrieving as a
> collection then adding to a TreeSet) What is the way to do this with
> OJB?
>
> --
> Jamo Smith
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> For additional commands, e-mail: ojb-user-help@db.apache.org
>
>
---------------------------------------------------------------------
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