Обсуждение: NULL Blob column error

My code has a table with an OID that's allowed to be NULL.  When I went to
retrieve the blob using a ResultSet.getBlob() call, I got an exception.  It
appears that a NULL OID value is not being handled correctly since it should
set the state within ResultSet so that I can call ResultSet.wasNull() to see
if the object was retrieved or not.

I received the following exception on 7.2.2:

FastPath call returned ERROR:  inv_open: large object 0 not found

        at org.postgresql.fastpath.Fastpath.fastpath(Fastpath.java:131)
        at org.postgresql.fastpath.Fastpath.fastpath(Fastpath.java:181)
        at org.postgresql.fastpath.Fastpath.getInteger(Fastpath.java:193)
        at
org.postgresql.largeobject.LargeObject.<init>(LargeObject.java:89)
        at
org.postgresql.largeobject.LargeObjectManager.open(LargeObjectManager.java:1
33)
        at org.postgresql.largeobject.PGblob.<init>(PGblob.java:37)
        at org.postgresql.jdbc2.ResultSet.getBlob(ResultSet.java:934)

Thanks,
David

Originally I thought this was going to be worse than I thought since I'm not
familiar with the fastpath code at all. However, a check of ResultSet.java
shows that the null check simply was not being done for getBlob().
Therefore, this patch for 7.2.2 will resolve the "FastPath call returned
ERROR:  inv_open: large object 0 not found" exception when retrieving
Blob/OID that is NULL.  I noted that this bug remains in the latest CVS as
well.

[postgresql@dev1 jdbc2]$ diff -c ResultSet.orig ResultSet.java
*** ResultSet.orig      Sat Jan  5 14:26:22 2002
--- ResultSet.java      Tue Sep 10 11:03:11 2002
***************
*** 931,936 ****
--- 931,940 ----

        public Blob getBlob(int i) throws SQLException
        {
+               wasNullFlag = (this_row[i - 1] == null);
+               if (wasNullFlag)
+                       return null;
+
                return new org.postgresql.largeobject.PGblob(connection,
getInt(i));
        }


David

Patch applied.

--Barry

David Wall wrote:
> Originally I thought this was going to be worse than I thought since I'm not
> familiar with the fastpath code at all. However, a check of ResultSet.java
> shows that the null check simply was not being done for getBlob().
> Therefore, this patch for 7.2.2 will resolve the "FastPath call returned
> ERROR:  inv_open: large object 0 not found" exception when retrieving
> Blob/OID that is NULL.  I noted that this bug remains in the latest CVS as
> well.
>
> [postgresql@dev1 jdbc2]$ diff -c ResultSet.orig ResultSet.java
> *** ResultSet.orig      Sat Jan  5 14:26:22 2002
> --- ResultSet.java      Tue Sep 10 11:03:11 2002
> ***************
> *** 931,936 ****
> --- 931,940 ----
>
>         public Blob getBlob(int i) throws SQLException
>         {
> +               wasNullFlag = (this_row[i - 1] == null);
> +               if (wasNullFlag)
> +                       return null;
> +
>                 return new org.postgresql.largeobject.PGblob(connection,
> getInt(i));
>         }
>
>
> David
>
>
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