How can I prevent some columns from fetching by default?

fitech · **Joined:** Wed Jul 30, 2008 8:43 am **Posts:** 32

Hi.

I have a blob column (byte[] field) and using Postgres. I need to avoid the fetch for this column by default and only fetch the field when I need to download the file, which is located there. How can I do this in Hibernate using annotations? I can write all columns in HQL query except for this blob and construct objects manually from fields. But this is not beautiful at all and seems more like a huck. Is there any other rapid and convenient way?

Thanks, Anton

niclasa · **Joined:** Sat Oct 01, 2011 1:16 pm **Posts:** 1

If I understand your problem correctly, you should be able to solve this by using lazy fetching.

For example, annotate your blob property like this:

@Basic(fetch=FetchType.LAZY)
private byte[] myLargeProperty;

(@Basic can be used together with the @Lob annotation if you already use that on the property.)

In this case, the property won't be fetched automatically. When calling the getMyLargeProperty() getter, a new SELECT will be issued that retrieves the field value.

fitech · **Joined:** Wed Jul 30, 2008 8:43 am **Posts:** 32

Niclas, thanks, but this didn't help.

I have the field with following notations:

Code:

    @NotNull 
    @Column(name="contentOid")
    @Basic(fetch=FetchType.LAZY)
    private byte[] content;

And use standard hql fetch:

Code:

em.createQuery("from BinaryDocument").getResultList()

This results in select for all columns, including the contentOid. Adding @Lob didn't help either...