Grokbase Groups Cayenne dev June 2007
FAQ
Sorry, I probably misunderstood your previous explanation:

"Split expressions are going to be critical to implementing
useful outer joins."

The changes I've made to CAY-514 are undone. What I was trying to do
(but probably did it wrong) is to categorize Jira's according to the
main concepts we are implementing: split expressions and outer joins.
Anyways, I'll leave it as it is :-)

Andrus

On Jun 12, 2007, at 7:17 PM, Mike Kienenberger wrote:
Andrus,

I don't think this is quite the same thing.

Split expressions are probably part of the solution to this problem,
but not the entire solution. Nor did this feature have to be
implemented in order to have useful outer joins.

I'd recommend reverting your change to this Jira issue and opening a
new issue just on outer joins.
On 6/12/07, Andrus Adamchik (JIRA) wrote:

[ https://issues.apache.org/cayenne/browse/CAY-514?
page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andrus Adamchik updated CAY-514:
--------------------------------

Summary: Split Expressions [implement a "MATCH ALL VALUES"
expression] (was: implement a "MATCH ALL VALUES" expression)

editing the name
Split Expressions [implement a "MATCH ALL VALUES" expression]
-------------------------------------------------------------

Key: CAY-514
URL: https://issues.apache.org/cayenne/browse/ CAY-514
Project: Cayenne
Issue Type: New Feature
Components: Cayenne Core Library
Affects Versions: 3.0
Reporter: Mike Kienenberger
Assignee: Mike Kienenberger
Fix For: 3.0


Implement a "Match all values" expression behavior (like
previously discussed as hasAllOfExp or MatchAllValuesExpression on
the mailing list in the past).
For example,
letters
a
b
c
digits
1
2
3
letters__digits
a-1
a-2
a-3
b-2
c-3
c-2
find all 1s: a
find all 2s: a, b, c
find all 3s: a, c
"Match all values" on (1, 2) would generate sql like the
following and
return "a"
select l1.* from letters l1, letters_digits ld1, digits d1, letters
l2, letters_digits ld1, digits d2 where
d1.value = '1' and ld1.digit_id = d1.digit_id and ld1.letter_id
= l1.letter_id
and
d2.value = '2' and ld2.digit_id = d2.digit_id and ld2.letter_id
= l2.letter_id
The current limitation is due to the fact that Cayenne qualifier
translator removes "duplicate" joins.
You'd have to introduce the "split" expression as discussed in
the threads below. Maybe use a pipe symbol at a place in the path
where a split should start, like "|r1" or "r1.r2.|r3"?? Second
thing to change is QueryAsembler.dbRelationshipAdded(..) method
that removes "duplicates" to support the splits.
There are a few more things to take care of to fully support
splits, so this is certainly not a trivial change.
Relevent threads discussing the idea and issues in more details:
http://www.objectstyle.org/cayenne/lists/cayenne-devel/
2003/09/0096.html
http://www.objectstyle.org/cayenne/lists/cayenne-devel/
2003/10/0005.html

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