I am unable to grasp the concept of the lookup table.
I am currently working on a project wherein I am using two tables.
The first table consists of two columns- name(varchar) and value(varchar).
The second table also has two rows- Result(varchar) and value(varchar).
Result is used to store the values which are obtained from a Java code. Whenever the Result of the Java code matches the name in the first table, I need to update the second table with the corresponding value in the first table.
Does using lookup table help in any way? If it does, can it be explained with an example?If not, is there any other way?
Just imagine a table person with a column GenderIsMale BIT. You can set this value to 1 (yes, it is a boy) or to 0 (no, a girl). This was easy in earlier days.
Now we have more categories. According to this link facebook offers more than 50 differing categories...
There the lookup-table comes into play: You create a table which has - as minium - a unique key and a value. In most cases this is an ID INT IDENTITY and a Content VARCHAR(100) NOT NULL. You can add more columns like Abbreviation or any other additional content (e.g. other languages or codes of external code systems read about mapping tables also) directly bound to this value.
The next step is, to take the GenderIsMale-column away and replace it with a
GenderID INT NOT NULL
CONSTRAINT FK_Person_GenderID FOREIGN KEY REFERENCES GenderLookUpTable(GenderID)
The person table will store the GenderID only, the related values are stored in the side table and can be looked up.
The simple lookup table is the basic construct of how to create a relational database model in min. 3.NF or BCNF (which should be a minium reuqirement for professional database design).
Whenever the Result of the Java code matches the name in the first
table, I need to update the second table with the corresponding value
in the first table.
That's a perfect use case for database trigger, which can be used to perform various things when a change (insert, update, delete) happens in a table.
Assuming you're inserting the value of your Java calculations to your (result, value) table (let's call it foo, and the other table is bar), you can write a trigger that replaces the value being written with the value from the other table. Example given for Postgres, if using another db refer to your particular RDBMS manual to see the syntax.
CREATE FUNCTION get_value_from_lookup_table() RETURNS trigger AS $$
BEGIN
IF EXISTS (SELECT 1 FROM bar WHERE name = NEW.result) THEN
RETURN SELECT name, value FROM bar WHERE name = NEW.result;
END IF;
RETURN NEW;
END;
$$ LANGUAGE plpgsql;
CREATE TRIGGER lookup_value
INSTEAD OF INSERT ON foo
FOR EACH ROW
EXECUTE PROCEDURE get_value_from_lookup_table();
Every time an INSERT is done on foo, a check is done to see if a row exists in bar where name=result. If so, that row is inserted, otherwise the insert goes on normally. That's the basic gist of it. The actual solution depends on table constraints, whether you need to handle inserts and updates, etc.
Several months ago I learned from an answer on Stack Overflow how to perform multiple updates at once in MySQL using the following syntax:
INSERT INTO table (id, field, field2) VALUES (1, A, X), (2, B, Y), (3, C, Z)
ON DUPLICATE KEY UPDATE field=VALUES(Col1), field2=VALUES(Col2);
I've now switched over to PostgreSQL and apparently this is not correct. It's referring to all the correct tables so I assume it's a matter of different keywords being used but I'm not sure where in the PostgreSQL documentation this is covered.
To clarify, I want to insert several things and if they already exist to update them.
PostgreSQL since version 9.5 has UPSERT syntax, with ON CONFLICT clause. with the following syntax (similar to MySQL)
INSERT INTO the_table (id, column_1, column_2)
VALUES (1, 'A', 'X'), (2, 'B', 'Y'), (3, 'C', 'Z')
ON CONFLICT (id) DO UPDATE
SET column_1 = excluded.column_1,
column_2 = excluded.column_2;
Searching postgresql's email group archives for "upsert" leads to finding an example of doing what you possibly want to do, in the manual:
Example 38-2. Exceptions with UPDATE/INSERT
This example uses exception handling to perform either UPDATE or INSERT, as appropriate:
CREATE TABLE db (a INT PRIMARY KEY, b TEXT);
CREATE FUNCTION merge_db(key INT, data TEXT) RETURNS VOID AS
$$
BEGIN
LOOP
-- first try to update the key
-- note that "a" must be unique
UPDATE db SET b = data WHERE a = key;
IF found THEN
RETURN;
END IF;
-- not there, so try to insert the key
-- if someone else inserts the same key concurrently,
-- we could get a unique-key failure
BEGIN
INSERT INTO db(a,b) VALUES (key, data);
RETURN;
EXCEPTION WHEN unique_violation THEN
-- do nothing, and loop to try the UPDATE again
END;
END LOOP;
END;
$$
LANGUAGE plpgsql;
SELECT merge_db(1, 'david');
SELECT merge_db(1, 'dennis');
There's possibly an example of how to do this in bulk, using CTEs in 9.1 and above, in the hackers mailing list:
WITH foos AS (SELECT (UNNEST(%foo[])).*)
updated as (UPDATE foo SET foo.a = foos.a ... RETURNING foo.id)
INSERT INTO foo SELECT foos.* FROM foos LEFT JOIN updated USING(id)
WHERE updated.id IS NULL;
See a_horse_with_no_name's answer for a clearer example.
Warning: this is not safe if executed from multiple sessions at the same time (see caveats below).
Another clever way to do an "UPSERT" in postgresql is to do two sequential UPDATE/INSERT statements that are each designed to succeed or have no effect.
UPDATE table SET field='C', field2='Z' WHERE id=3;
INSERT INTO table (id, field, field2)
SELECT 3, 'C', 'Z'
WHERE NOT EXISTS (SELECT 1 FROM table WHERE id=3);
The UPDATE will succeed if a row with "id=3" already exists, otherwise it has no effect.
The INSERT will succeed only if row with "id=3" does not already exist.
You can combine these two into a single string and run them both with a single SQL statement execute from your application. Running them together in a single transaction is highly recommended.
This works very well when run in isolation or on a locked table, but is subject to race conditions that mean it might still fail with duplicate key error if a row is inserted concurrently, or might terminate with no row inserted when a row is deleted concurrently. A SERIALIZABLE transaction on PostgreSQL 9.1 or higher will handle it reliably at the cost of a very high serialization failure rate, meaning you'll have to retry a lot. See why is upsert so complicated, which discusses this case in more detail.
This approach is also subject to lost updates in read committed isolation unless the application checks the affected row counts and verifies that either the insert or the update affected a row.
With PostgreSQL 9.1 this can be achieved using a writeable CTE (common table expression):
WITH new_values (id, field1, field2) as (
values
(1, 'A', 'X'),
(2, 'B', 'Y'),
(3, 'C', 'Z')
),
upsert as
(
update mytable m
set field1 = nv.field1,
field2 = nv.field2
FROM new_values nv
WHERE m.id = nv.id
RETURNING m.*
)
INSERT INTO mytable (id, field1, field2)
SELECT id, field1, field2
FROM new_values
WHERE NOT EXISTS (SELECT 1
FROM upsert up
WHERE up.id = new_values.id)
See these blog entries:
Upserting via Writeable CTE
WAITING FOR 9.1 – WRITABLE CTE
WHY IS UPSERT SO COMPLICATED?
Note that this solution does not prevent a unique key violation but it is not vulnerable to lost updates.
See the follow up by Craig Ringer on dba.stackexchange.com
In PostgreSQL 9.5 and newer you can use INSERT ... ON CONFLICT UPDATE.
See the documentation.
A MySQL INSERT ... ON DUPLICATE KEY UPDATE can be directly rephrased to a ON CONFLICT UPDATE. Neither is SQL-standard syntax, they're both database-specific extensions. There are good reasons MERGE wasn't used for this, a new syntax wasn't created just for fun. (MySQL's syntax also has issues that mean it wasn't adopted directly).
e.g. given setup:
CREATE TABLE tablename (a integer primary key, b integer, c integer);
INSERT INTO tablename (a, b, c) values (1, 2, 3);
the MySQL query:
INSERT INTO tablename (a,b,c) VALUES (1,2,3)
ON DUPLICATE KEY UPDATE c=c+1;
becomes:
INSERT INTO tablename (a, b, c) values (1, 2, 10)
ON CONFLICT (a) DO UPDATE SET c = tablename.c + 1;
Differences:
You must specify the column name (or unique constraint name) to use for the uniqueness check. That's the ON CONFLICT (columnname) DO
The keyword SET must be used, as if this was a normal UPDATE statement
It has some nice features too:
You can have a WHERE clause on your UPDATE (letting you effectively turn ON CONFLICT UPDATE into ON CONFLICT IGNORE for certain values)
The proposed-for-insertion values are available as the row-variable EXCLUDED, which has the same structure as the target table. You can get the original values in the table by using the table name. So in this case EXCLUDED.c will be 10 (because that's what we tried to insert) and "table".c will be 3 because that's the current value in the table. You can use either or both in the SET expressions and WHERE clause.
For background on upsert see How to UPSERT (MERGE, INSERT ... ON DUPLICATE UPDATE) in PostgreSQL?
I was looking for the same thing when I came here, but the lack of a generic "upsert" function botherd me a bit so I thought you could just pass the update and insert sql as arguments on that function form the manual
that would look like this:
CREATE FUNCTION upsert (sql_update TEXT, sql_insert TEXT)
RETURNS VOID
LANGUAGE plpgsql
AS $$
BEGIN
LOOP
-- first try to update
EXECUTE sql_update;
-- check if the row is found
IF FOUND THEN
RETURN;
END IF;
-- not found so insert the row
BEGIN
EXECUTE sql_insert;
RETURN;
EXCEPTION WHEN unique_violation THEN
-- do nothing and loop
END;
END LOOP;
END;
$$;
and perhaps to do what you initially wanted to do, batch "upsert", you could use Tcl to split the sql_update and loop the individual updates, the preformance hit will be very small see http://archives.postgresql.org/pgsql-performance/2006-04/msg00557.php
the highest cost is executing the query from your code, on the database side the execution cost is much smaller
There is no simple command to do it.
The most correct approach is to use function, like the one from docs.
Another solution (although not that safe) is to do update with returning, check which rows were updates, and insert the rest of them
Something along the lines of:
update table
set column = x.column
from (values (1,'aa'),(2,'bb'),(3,'cc')) as x (id, column)
where table.id = x.id
returning id;
assuming id:2 was returned:
insert into table (id, column) values (1, 'aa'), (3, 'cc');
Of course it will bail out sooner or later (in concurrent environment), as there is clear race condition in here, but usually it will work.
Here's a longer and more comprehensive article on the topic.
I use this function merge
CREATE OR REPLACE FUNCTION merge_tabla(key INT, data TEXT)
RETURNS void AS
$BODY$
BEGIN
IF EXISTS(SELECT a FROM tabla WHERE a = key)
THEN
UPDATE tabla SET b = data WHERE a = key;
RETURN;
ELSE
INSERT INTO tabla(a,b) VALUES (key, data);
RETURN;
END IF;
END;
$BODY$
LANGUAGE plpgsql
Personally, I've set up a "rule" attached to the insert statement. Say you had a "dns" table that recorded dns hits per customer on a per-time basis:
CREATE TABLE dns (
"time" timestamp without time zone NOT NULL,
customer_id integer NOT NULL,
hits integer
);
You wanted to be able to re-insert rows with updated values, or create them if they didn't exist already. Keyed on the customer_id and the time. Something like this:
CREATE RULE replace_dns AS
ON INSERT TO dns
WHERE (EXISTS (SELECT 1 FROM dns WHERE ((dns."time" = new."time")
AND (dns.customer_id = new.customer_id))))
DO INSTEAD UPDATE dns
SET hits = new.hits
WHERE ((dns."time" = new."time") AND (dns.customer_id = new.customer_id));
Update: This has the potential to fail if simultaneous inserts are happening, as it will generate unique_violation exceptions. However, the non-terminated transaction will continue and succeed, and you just need to repeat the terminated transaction.
However, if there are tons of inserts happening all the time, you will want to put a table lock around the insert statements: SHARE ROW EXCLUSIVE locking will prevent any operations that could insert, delete or update rows in your target table. However, updates that do not update the unique key are safe, so if you no operation will do this, use advisory locks instead.
Also, the COPY command does not use RULES, so if you're inserting with COPY, you'll need to use triggers instead.
Similar to most-liked answer, but works slightly faster:
WITH upsert AS (UPDATE spider_count SET tally=1 WHERE date='today' RETURNING *)
INSERT INTO spider_count (spider, tally) SELECT 'Googlebot', 1 WHERE NOT EXISTS (SELECT * FROM upsert)
(source: http://www.the-art-of-web.com/sql/upsert/)
I custom "upsert" function above, if you want to INSERT AND REPLACE :
`
CREATE OR REPLACE FUNCTION upsert(sql_insert text, sql_update text)
RETURNS void AS
$BODY$
BEGIN
-- first try to insert and after to update. Note : insert has pk and update not...
EXECUTE sql_insert;
RETURN;
EXCEPTION WHEN unique_violation THEN
EXECUTE sql_update;
IF FOUND THEN
RETURN;
END IF;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
ALTER FUNCTION upsert(text, text)
OWNER TO postgres;`
And after to execute, do something like this :
SELECT upsert($$INSERT INTO ...$$,$$UPDATE... $$)
Is important to put double dollar-comma to avoid compiler errors
check the speed...
According the PostgreSQL documentation of the INSERT statement, handling the ON DUPLICATE KEY case is not supported. That part of the syntax is a proprietary MySQL extension.
I have the same issue for managing account settings as name value pairs.
The design criteria is that different clients could have different settings sets.
My solution, similar to JWP is to bulk erase and replace, generating the merge record within your application.
This is pretty bulletproof, platform independent and since there are never more than about 20 settings per client, this is only 3 fairly low load db calls - probably the fastest method.
The alternative of updating individual rows - checking for exceptions then inserting - or some combination of is hideous code, slow and often breaks because (as mentioned above) non standard SQL exception handling changing from db to db - or even release to release.
#This is pseudo-code - within the application:
BEGIN TRANSACTION - get transaction lock
SELECT all current name value pairs where id = $id into a hash record
create a merge record from the current and update record
(set intersection where shared keys in new win, and empty values in new are deleted).
DELETE all name value pairs where id = $id
COPY/INSERT merged records
END TRANSACTION
CREATE OR REPLACE FUNCTION save_user(_id integer, _name character varying)
RETURNS boolean AS
$BODY$
BEGIN
UPDATE users SET name = _name WHERE id = _id;
IF FOUND THEN
RETURN true;
END IF;
BEGIN
INSERT INTO users (id, name) VALUES (_id, _name);
EXCEPTION WHEN OTHERS THEN
UPDATE users SET name = _name WHERE id = _id;
END;
RETURN TRUE;
END;
$BODY$
LANGUAGE plpgsql VOLATILE STRICT
For merging small sets, using the above function is fine. However, if you are merging large amounts of data, I'd suggest looking into http://mbk.projects.postgresql.org
The current best practice that I'm aware of is:
COPY new/updated data into temp table (sure, or you can do INSERT if the cost is ok)
Acquire Lock [optional] (advisory is preferable to table locks, IMO)
Merge. (the fun part)
UPDATE will return the number of modified rows. If you use JDBC (Java), you can then check this value against 0 and, if no rows have been affected, fire INSERT instead. If you use some other programming language, maybe the number of the modified rows still can be obtained, check documentation.
This may not be as elegant but you have much simpler SQL that is more trivial to use from the calling code. Differently, if you write the ten line script in PL/PSQL, you probably should have a unit test of one or another kind just for it alone.
Edit: This does not work as expected. Unlike the accepted answer, this produces unique key violations when two processes repeatedly call upsert_foo concurrently.
Eureka! I figured out a way to do it in one query: use UPDATE ... RETURNING to test if any rows were affected:
CREATE TABLE foo (k INT PRIMARY KEY, v TEXT);
CREATE FUNCTION update_foo(k INT, v TEXT)
RETURNS SETOF INT AS $$
UPDATE foo SET v = $2 WHERE k = $1 RETURNING $1
$$ LANGUAGE sql;
CREATE FUNCTION upsert_foo(k INT, v TEXT)
RETURNS VOID AS $$
INSERT INTO foo
SELECT $1, $2
WHERE NOT EXISTS (SELECT update_foo($1, $2))
$$ LANGUAGE sql;
The UPDATE has to be done in a separate procedure because, unfortunately, this is a syntax error:
... WHERE NOT EXISTS (UPDATE ...)
Now it works as desired:
SELECT upsert_foo(1, 'hi');
SELECT upsert_foo(1, 'bye');
SELECT upsert_foo(3, 'hi');
SELECT upsert_foo(3, 'bye');
PostgreSQL >= v15
Big news on this topic as in PostgreSQL v15, it is possible to use MERGE command. In fact, this long awaited feature was listed the first of the improvements of the v15 release.
This is similar to INSERT ... ON CONFLICT but more batch-oriented. It has a powerful WHEN MATCHED vs WHEN NOT MATCHED structure that gives the ability to INSERT, UPDATE or DELETE on such conditions.
It not only eases bulk changes, but it even adds more control that tradition UPSERT and INSERT ... ON CONFLICT
Take a look at this very complete sample from official page:
MERGE INTO wines w
USING wine_stock_changes s
ON s.winename = w.winename
WHEN NOT MATCHED AND s.stock_delta > 0 THEN
INSERT VALUES(s.winename, s.stock_delta)
WHEN MATCHED AND w.stock + s.stock_delta > 0 THEN
UPDATE SET stock = w.stock + s.stock_delta
WHEN MATCHED THEN
DELETE;
PostgreSQL v9, v10, v11, v12, v13, v14
If version is under v15 and over v9.5 , probably best choice is to use UPSERT syntax, with ON CONFLICT clause
Here is the example how to do upsert with params and without special sql constructions
if you have special condition (sometimes you can't use 'on conflict' because you can't create constraint)
WITH upd AS
(
update view_layer set metadata=:metadata where layer_id = :layer_id and view_id = :view_id returning id
)
insert into view_layer (layer_id, view_id, metadata)
(select :layer_id layer_id, :view_id view_id, :metadata metadata FROM view_layer l
where NOT EXISTS(select id FROM upd WHERE id IS NOT NULL) limit 1)
returning id
maybe it will be helpful
I'm trying to insert a new record using UpdatableRecords in jOOQ 3.4.2. The pattern is extremely concise and pleasant to use, except that the INSERT reads null values as no value and ignores default values or a generated index. How can I use the UpdatableRecord to do an insert that respects default values and generated indexes?
Here's my table:
CREATE TABLE aragorn_sys.org_person (
org_person_id SERIAL NOT NULL,
first_name CHARACTER VARYING(128) NOT NULL,
last_name CHARACTER VARYING(128) NOT NULL,
created_time TIMESTAMP WITH TIME ZONE DEFAULT current_timestamp NOT NULL,
created_by_user_id INTEGER,
last_modified_time TIMESTAMP WITH TIME ZONE,
last_modified_by_user_id INTEGER,
org_id INTEGER NOT NULL,
CONSTRAINT PK_org_person PRIMARY KEY (org_person_id)
);
Note my primary key and default values. Now here's my jOOQ code:
// orgPerson represents a POJO filled with my values to be inserted and null for everything else
// Note that orgPerson.orgPersonId is null
OrgPersonRecord orgPersonRecord = create.newRecord( ORG_PERSON, orgPerson );
Integer orgPersonId = create.executeInsert( orgPersonRecord );
But when I run this, I get the error null value in column "org_person_id" violates not-null constraint.
I noticed the jOOQ docs say that calling newRecord automatically sets all the internal "changed" flags to true on the UpdatableRecord. So then I tried this:
// orgPerson represents a POJO filled with my values to be inserted and null for everything else
// Note that orgPerson.orgPersonId is null
OrgPersonRecord orgPersonRecord = create.newRecord( ORG_PERSON, orgPerson );
orgPersonRecord.changed( ORG_PERSON.ORG_PERSON_ID, false );
orgPersonRecord.changed( ORG_PERSON.CREATED_TIME, false );
orgPersonRecord.insert()
Integer orgPersonId = orgPersonRecord.getOrgPersonId();
But that gives me the error ERROR: duplicate key value violates unique constraint "pk_org_person". And when I do this repeatedly, the values seem to keep increasing by 1. This doesn't really make sense to me, but my greater question is: Is there a good way I can do an INSERT based on my object values, or better yet, simply include only the non-null columns?
I saw JOOQ ignoring database columns with default values, but that doesn't seem to resolve this. Any recommendations on the most concise way to handle this?
By the way, jOOQ has been fantastic to work with so far. Lukas, thank you for this awesome tool!
UPDATE #1:
The "not null issue" is addressed by Lukas's answer below, and that's an easy fix.
For the duplicate primary keys, I am definitely not confusing INSERT with UPDATE. When I run the above code (slight update since original post), jOOQ seems to arbitrarily pick a "starting" primary key value for OrgPersonId. For example, when I first load up my environment, jOOQ might start with "11" for OrgPersonId.
Then, when I do an INSERT, jOOQ will attempt to supply a value of "11" for OrgPersonId, I'll get the ERROR: duplicate key value and the INSERT will fail. If I then repeat the INSERT, jOOQ uses "12", then "13". It succeeds or fails based on whether that ID is available, but it's not "starting" with the right ID.
The manual (http://www.jooq.org/doc/3.4/manual/sql-execution/crud-with-updatablerecords/identity-values/) says that If you're using jOOQ's code generator, the above table will generate a org.jooq.UpdatableRecord with an IDENTITY column. This information is used by jOOQ internally, to update IDs after calling store().
UPDATE #2:
Ok, I just tried the generated query directly in Postgres and it fails there, too, with the same issue. So, clearly this is a Postgres issue and not a jOOQ issue. I'll post the final resolution on that when I find it in case anyone else runs into this.
UPDATE #3:
Issue has been resolved. We use FlywayDB (another awesome tool) to automate our database schema migration, and we had a bunch of INSERT statements in our Flyway scripts that manually INSERTED the id number. This was convenient because we wanted to create a bunch of dummy data and wanted to guarantee the right foreign key relationships.
But manually specifying the primary key increment does not advance the Postgres sequence! Hence, we had to cycle through the Postgres sequence before (correctly operating) jOOQ would get the right sequence value.
Solution is to remove all our manual inserts of the primary keys in our demo data migration scripts.
violates not-null constraint
The first part that you're describing is a flaw (#3582), which is related to a previous issue (#2700), which enforced storing null values loaded from POJOs into jOOQ Records for database columns that are NOT NULL. The fix will be in jOOQ 3.5.0, 3.4.3, 3.3.4, and 3.2.7
duplicate key value violates unique constraint "pk_org_person"
The second part probably is caused by the fact that you are really loading an existing record and then calling executeInsert() on it (observe the INSERT, which will always execute an INSERT statement). You might want to call executeUpdate(), instead
I have a table "groups" with four columns. The database is postgres and the group_id column is a Serial. So in reality it is an Integer with a default to get the next value.
I have a use case where I need to use #SQLInsert (using the normal persist method is not an option), but I can't get it to work with the default. Here is what I have:
#SQLInsert(sql="INSERT INTO groups (group_id, parent_id, group_name, version) VALUES (DEFAULT,?,?,?)")
I set the entity attributes to values where group_id and version are null, and the other two are correctly populated. group_id is not nullable in the DB, version can be null.
I get this exception:
WARNING: SQL Error: 0, SQLState: 22023
SEVERE: The column index is out of range: 4, number of columns: 3.
SEVERE: Could not synchronize database state with session
If I enter the following DML directly on the database, it works:
INSERT INTO groups (group_id, parent_id, group_name, version) VALUES (DEFAULT, 3, 'abcd', null);
Is there some way to make the same thing happen using #SQLInsert.
If the class members which you want to save are not reference types they can not hold a null value. It may be the cause of failure in synchronization with database records. Try to use reference types like Integer and Double, etc. And get sure that default values are assumed with a direct insert query.
Another thing in your error messages. It may the default value is out of boundary of the type you are using in Java for that column. Check the default value to be in range. If a value out of range is set for your class member, it can't be synced.
EDIT: Sorry, the second part is not true in this case.
So the short answer is "it can't be done this way". Despite quite a few places I've seen this asked, the Hibernate people have not provided for this use case.
My solution was to decouple the Postgres sequence from the table. That is, I removed the default constraint that selects the nextval from the sequence and populates one of the two primary key fields.
I then manually grab the nextval using a native query (yep, forced to un-abstract the database), and use that value to manually populate the primary key field. It works. It's kludgy, but I might use it more often. It certainly is a lot more understandable as to what is happening than using the pure ORM methods. This can be debugged without a wizards hat. :)
public class...
#PersistenceContext(unitName = "persistence_unit")
private EntityManager em;
...
mymethod(){
...
Query q = em.createNativeQuery("SELECT nextval('groups_group_id_seq')");
BigInteger groupId = (BigInteger)q.getSingleResult();
BigInteger parentId = methodToGetParentId();
GroupsPK gpk = new GroupsPK(groupId, parentId);
Groups grps = new Groups(gpk, "other parameters");
...
}