Bad SQL in 2.3.1 with n*m collection

Question

Hi guys,
This bug comes from an example in my book. The Library example is one of the JDO Learning Tools
that I am providing that allows the user to enter queries interactively. The bug arises in an
example of its use presented in the book. Abe will receive the code with Chapter 8, coming soon.
Basically, Volunteer has a 1 to 1 relation with Borrower. A Borrower has a 1 to M relation with
Book. Book has a N to M relation with Category. Or in object terms, a Volunteer is always a
Borrower, but a Borrower is not always a Volunteer. A Book can be borrowed by one Borrower. A
Borrower can borrow from 0 to M books. A Book can be in the books collection of any number of
Category objects, and a Category can be in the categories collection of any number of Book objects.
Here is the JDO metadata:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE jdo SYSTEM "jdo.dtd">
<jdo>
<package name="com.ysoft.jdo.book.library">
<class name="Borrower" identity-type="datastore" >
<field name="oidString" persistence-modifier="none" />
<field name="books" >
<collection element-type="com.ysoft.jdo.book.library.Book" />
<extension vendor-name="kodo" key="inverse" value="borrower"/>
</field>
</class>
<class name="Book" identity-type="datastore" >
<field name="oidString" persistence-modifier="none" />
<field name="borrower" />
<field name="categories" >
<collection element-type="com.ysoft.jdo.book.library.Category" />
<extension vendor-name="kodo" key="inverse" value="books"/>
</field>
</class>
<class name="Category" identity-type="datastore" >
<field name="oidString" persistence-modifier="none" />
<field name="books" >
<collection element-type="com.ysoft.jdo.book.library.Book" />
<extension vendor-name="kodo" key="inverse" value="categories"/>
</field>
</class>
<class name="Volunteer" identity-type="datastore" >
<field name="oidString" persistence-modifier="none" />
</class>
</package>
</jdo>
Here is the example as presented in the book, this is quoting output from the JDORI.
-- begin quote --
To find all the books that are in categories that interest Harry, use the Book extent, and define
the query variables:
Book b; Category c;
Then use the query string:
categories.contains(c) && (c.books.contains(b) && b.borrower.name == "Harry")
Your answer for the default object population should be:
Found 1 objects in the results
book [OID: 102-16] "Gone to Work" checked out: Mon Aug 26 08:23:10 EDT 2002
-- end quote --
Here is the SQL that KODO produces. It finds many (or all?) books instead of 1.
SELECT DISTINCT
t0.JDOIDX,
t0.JDOCLASSX,
t0.JDOLOCKX,
t0.BORROWERX,
t0.CHECKOUTX,
t0.TITLEX
FROM BOOKX t0, BOOKX t5, BOOKX t6,
BOOK_CATEGORIESX t1, BOOK_CATEGORIESX t4,
BORROWERX t7, CATEGORYX t2, CATEGORYX t3
WHERE (t7.NAMEX = 'Harry'
AND t0.JDOIDX = t1.JDOIDX
AND t1.CATEGORIESX = t2.JDOIDX
AND t3.JDOIDX = t4.CATEGORIESX
AND t4.JDOIDX = t5.JDOIDX
AND t6.BORROWERX = t7.JDOIDX)
Here is the modified version that gets the job done:
SELECT
t0.JDOIDX,
t0.JDOCLASSX,
t0.JDOLOCKX,
t0.BORROWERX,
t0.CHECKOUTX,
t0.TITLEX
FROM BOOKX t0,
BOOK_CATEGORIESX t1,
CATEGORYX t2,
BORROWERX t3
WHERE (t3.NAMEX = 'Harry'
AND t0.JDOIDX = t1.JDOIDX
AND t1.CATEGORIESX = t2.JDOIDX
AND t0.BORROWERX = t3.JDOIDX)
David Ezzio

Answer 1

David,
This has been fixed internally, and will be available in 2.3.3 (hopefully
along with a fix to your other issue).
-Patrick
In article <[email protected]>, David Ezzio wrote:
Hi guys,
This bug continues to exist in 2.3.2
David Ezzio
David Ezzio wrote:
Hi guys,
This bug comes from an example in my book. The Library example is one of the JDO Learning Tools
that I am providing that allows the user to enter queries interactively. The bug arises in an
example of its use presented in the book. Abe will receive the code with Chapter 8, coming soon.
Basically, Volunteer has a 1 to 1 relation with Borrower. A Borrower has a 1 to M relation with
Book. Book has a N to M relation with Category. Or in object terms, a Volunteer is always a
Borrower, but a Borrower is not always a Volunteer. A Book can be borrowed by one Borrower. A
Borrower can borrow from 0 to M books. A Book can be in the books collection of any number of
Category objects, and a Category can be in the categories collection of any number of Book objects.
Here is the JDO metadata:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE jdo SYSTEM "jdo.dtd">
<jdo>
<package name="com.ysoft.jdo.book.library">
<class name="Borrower" identity-type="datastore" >
<field name="oidString" persistence-modifier="none" />
<field name="books" >
<collection element-type="com.ysoft.jdo.book.library.Book" />
<extension vendor-name="kodo" key="inverse" value="borrower"/>
</field>
</class>
<class name="Book" identity-type="datastore" >
<field name="oidString" persistence-modifier="none" />
<field name="borrower" />
<field name="categories" >
<collection element-type="com.ysoft.jdo.book.library.Category" />
<extension vendor-name="kodo" key="inverse" value="books"/>
</field>
</class>
<class name="Category" identity-type="datastore" >
<field name="oidString" persistence-modifier="none" />
<field name="books" >
<collection element-type="com.ysoft.jdo.book.library.Book" />
<extension vendor-name="kodo" key="inverse" value="categories"/>
</field>
</class>
<class name="Volunteer" identity-type="datastore" >
<field name="oidString" persistence-modifier="none" />
</class>
</package>
</jdo>
Here is the example as presented in the book, this is quoting output from the JDORI.
-- begin quote --
To find all the books that are in categories that interest Harry, use the Book extent, and define
the query variables:
Book b; Category c;
Then use the query string:
categories.contains(c) && (c.books.contains(b) && b.borrower.name == "Harry")
Your answer for the default object population should be:
Found 1 objects in the results
book [OID: 102-16] "Gone to Work" checked out: Mon Aug 26 08:23:10 EDT 2002
-- end quote --
Here is the SQL that KODO produces. It finds many (or all?) books instead of 1.
SELECT DISTINCT
t0.JDOIDX,
t0.JDOCLASSX,
t0.JDOLOCKX,
t0.BORROWERX,
t0.CHECKOUTX,
t0.TITLEX
FROM BOOKX t0, BOOKX t5, BOOKX t6,
BOOK_CATEGORIESX t1, BOOK_CATEGORIESX t4,
BORROWERX t7, CATEGORYX t2, CATEGORYX t3
WHERE (t7.NAMEX = 'Harry'
AND t0.JDOIDX = t1.JDOIDX
AND t1.CATEGORIESX = t2.JDOIDX
AND t3.JDOIDX = t4.CATEGORIESX
AND t4.JDOIDX = t5.JDOIDX
AND t6.BORROWERX = t7.JDOIDX)
Here is the modified version that gets the job done:
SELECT
t0.JDOIDX,
t0.JDOCLASSX,
t0.JDOLOCKX,
t0.BORROWERX,
t0.CHECKOUTX,
t0.TITLEX
FROM BOOKX t0,
BOOK_CATEGORIESX t1,
CATEGORYX t2,
BORROWERX t3
WHERE (t3.NAMEX = 'Harry'
AND t0.JDOIDX = t1.JDOIDX
AND t1.CATEGORIESX = t2.JDOIDX
AND t0.BORROWERX = t3.JDOIDX)
David Ezzio
Patrick Linskey [email protected]
SolarMetric Inc. http://www.solarmetric.com