Difference between revisions of "EclipseLink/Development/2.1/AdvancedJPA Queries"

Revision as of 10:05, 19 January 2010

bug 219814

Extensions to be implemented - in priority order

All database functions

http://www.eclipse.org/forums/index.phpt=msg&th=124404&start=0&S=6eb7686393e997064947f7e51e5aca88

JPQL equivalent to Oracle's NVL function

Spatial Functionality via JPQL

PostGIS Intersects (forum)

Oracle Spatial

• SDO_WITHIN_DISTANCE
• SDO_NN
• SDO_RELATE
• SDO_FILTER

Functions in select and order by clause

http://forums.oracle.com/forums/thread.jspa?messageID=3903302&#3903302

http://dev.eclipse.org/mhonarc/lists/eclipselink-users/msg03720.html

Already works for select clause (tested ABS), doesn’t work for order by clause.

However fails:

SELECT CONCAT(e.firstName, e.lastName) FROM Employee e

but works:

SELECT CONCAT(e.firstName, e.lastName) FROM Employee e WHERE e.id > 0

Order by should be applicable to any field type

http://forums.oracle.com/forums/thread.jspa?threadID=870722

Fields and tables, "from X x, Table(Y) y", "x.field(y)"

?

Object parameters and nested parameters "(:employee).id"

Saw several times users attempting something like:

SELECT e FROM Employee e WHERE e.address IN (SELECT a FROM Address…)

Fetch groups "Select emp(id, name) from Employee emp"

?

SQL Hints

Currently EclipseLink supports specifying (Oracle) SQL hints using [ DatabaseQuery.setHintString("...")] (see Using_Advanced_Query_API_(ELUG)#How_to_Use_Oracle_Hints) or through JPA using QueryHints.HINT. These hints are limited in where they can be generated in the resulting SQL.

These appear to be Oracle specific. Is this approach useful on other database platforms?

HIERARCHICAL QUERIES (Oracle)

ELUG: Using_Advanced_Query_API_(ELUG)#How_to_Use_Hierarchical_Queries

• START WITH
• CONNECT BY
• ORDER SIBLINGS

Pessimistic locking "for update of emp"

Accessible through hints ("for update" only).

Batch joins

http://www.eclipse.org/forums/index.php?t=msg&th=123943&start=0&S=f9832b9dae179e13094b3c027540647f

Accessible through hints.

Extensions already implemented in 2.0

Like with escapes, any types

Works for strings:

SELECT e FROM Employee e WHERE e.firstName LIKE "John"

Have not tested for other types.

Which types should be tested?

Nested fetch joins (both inner and outer)

http://www.eclipse.org/forums/index.php?t=msg&goto=379275&#msg_379275

http://www.eclipse.org/forums/index.php?&t=msg&th=125842

Inner:

SELECT p FROM SmallProject p JOIN p.teamLeader e JOIN e.address a WHERE p.name = 'Project1' or e.firstName = 'John' and a.province = 'ON'

with setHint("eclipselink.join-fetch", "p.teamLeader.address")

Outer:

SELECT p FROM SmallProject p LEFT JOIN p.teamLeader e LEFT JOIN e.address a WHERE p.name = 'Project1' or e.firstName = 'John' and a.province = 'ON'

with setHint("eclipselink.left-join-fetch", "p.teamLeader.address")

Note that aliasing on the right side of FETCH is explicitly prohibited by the spec., so seems like no extension in JBQL is possible.

Pass list as parameter

SELECT e FROM Employee e WHERE e.id in :list

http://forums.oracle.com/forums/thread.jspa?threadID=871532