从 DB2 仓库中的列组织表中获取生成的密钥

Question

I am not able to get generated key from column organized table from an INSERT SQL statement run against IBM DB2 warehouse. I am using Java and JDBC driver. Everything works fine - I am able to connect to DB, create tables, insert data, I am just not able to get a generated key if it is generated in column organized table. Note that row organized tables work fine and return the key properly.

Consider a table:

CREATE TABLE users (
   id       INTEGER not null GENERATED ALWAYS AS IDENTITY (START WITH 1 INCREMENT BY 1),
   username VARCHAR(16),
   PRIMARY KEY (id)
);

If this is row organized table I am able to get the generated key fine by using:

PreparedStatement pr = connection.prepareStatement("INSERT INTO users(username) VALUES(?)", PreparedStatement.RETURN_GENERATED_KEYS);

However, If this is column organized table the PreparedStatemnt creation fails with an error:

com.ibm.db2.jcc.am.SqlSyntaxErrorException: DB2 SQL Error: SQLCODE=-1667, SQLSTATE=42858, SQLERRMC=BLUADMIN.USERS;ORGANIZE BY COLUMN;FINAL|NEW|OLD TABLE, DRIVER=4.25.13

Even if I specify columns I want to get returned like so:

PreparedStatement pr = connection.prepareStatement("INSERT INTO users(username) VALUES(?)", new String[]{"id","username"});

pr.setString(1, "test");
pr.executeUpdate();   

I get

com.ibm.db2.jcc.am.SqlSyntaxErrorException: DB2 SQL Error: SQLCODE=-1667, SQLSTATE=42858, SQLERRMC=BLUADMIN.USERS;ORGANIZE BY COLUMN;FINAL|NEW|OLD TABLE, DRIVER=4.25.13

on line pr.executeUpdate(); .

Does this mean that it is not possible to get generated key from column organized table from the INSERT statement in DB2 Warehouse?

Answer 1

Have you tried actually selecting the generated ID? Try something like this:

SELECT ID FROM FINAL TABLE
    (INSERT INTO users(username) VALUES(?))

See " Retrieval of result sets from an SQL data change statement " in the IBM Db2 documentation.

Answer 2

Currently shipping versions v11.1.x and V11.5.x will throw SQL1667N when the query sent to Db2 uses 'FINAL TABLE' or 'OLD TABLE', or 'NEW TABLE' clauses for a column organized table.

When you use the jdbc syntax PreparedStatement.RETURN_GENERATED_KEYS , this syntax may be used under the covers.

Currently those clauses are not supported (ie will cause the exception to be thrown) for ORGANIZE BY COLUMN tables. There are other restrictions on column organized tables that you should be aware of before using them.

You can workaround this by creating your tables explicitly with the ORGANIZE BY ROW clause.