Db2: Eclipselink creates table with Db2 data type DOUBLE instead of REAL for a Java float

[mswatosh]

For an entity with Java float attributes, using jakarta.persistence.schema-generation.database.action results in columns being created as Double (64-bit precision) instead of Real (32-bit precision). This is due to Eclipselink attempting to create the column as Float instead of Real: CREATE TABLE Packages (ID INTEGER NOT NULL, DESCRIPTION VARCHAR(255), HEIGHT FLOAT, LENGTH FLOAT, WIDTH FLOAT, PRIMARY KEY (ID))

This results in the following:

                                Data type                     Column
Column name                     schema    Data type name      Length     Scale Nulls
------------------------------- --------- ------------------- ---------- ----- ------
ID                              SYSIBM    INTEGER                      4     0 No    
DESCRIPTION                     SYSIBM    VARCHAR                    255     0 Yes   
HEIGHT                          SYSIBM    DOUBLE                       8     0 Yes   
LENGTH                          SYSIBM    DOUBLE                       8     0 Yes   
WIDTH                           SYSIBM    DOUBLE                       8     0 Yes   

persistence.xml

<property name="jakarta.persistence.schema-generation.database.action" value="drop-and-create"/>

Package.java

@Entity
@Table(name = "Packages")
public class Package {

    public String description;

    @Id
    public int id;

    public float height;

    public float length;

    public float width;

The end result of this is the first time an entity is persisted on a db2 connection, the float values can be slightly off due to the precision change from 32 bit to 64 bit. This can result in incorrect sorting like this issue: https://github.com/eclipse-ee4j/eclipselink/issues/2194

[mswatosh]

I'm not sure if this is the only place, but essentially:

https://github.com/eclipse-ee4j/eclipselink/blob/ec0c9cdda67c6e88813a78ce4b2b3e3968fef15c/foundation/org.eclipse.persistence.core/src/main/java/org/eclipse/persistence/platform/database/DB2Platform.java#L314C10-L314C84

        fieldTypeMapping.put(Float.class, new FieldTypeDefinition("FLOAT", false));
        fieldTypeMapping.put(Double.class, new FieldTypeDefinition("FLOAT", false));

should be

        fieldTypeMapping.put(Float.class, new FieldTypeDefinition("REAL", false));
        fieldTypeMapping.put(Double.class, new FieldTypeDefinition("FLOAT", false));

[ajaypaul-ibm]

Hi @mswatosh Can you please close this issue ? Thanks !