SQL error not occurs again after refresh

Hello,

I have one SQL statement like following:

       SELECT DISTINCT

         a~objkey AS guid_parent

         b~objkey AS guid_child

       INTO CORRESPONDING FIELDS OF TABLE et_parent_object

       FROM srrelroles AS a

       INNER JOIN crmd_binrel AS r ON a~roleid = r~role_a

       INNER JOIN srrelroles  AS b ON b~roleid = r~role_b

       WHERE a~objkey IS NOT NULL

         AND b~objkey IS NOT NULL

         AND a~objkey IN lt_parents_range.

The parameter lt_parents_range has more than 1000 lines.

First time, when I run this SQL, dump occurs. Like following:

Category                   Installation Errors

Runtime Errors          DBIF_RSQL_SQL_ERROR

Except.                    CX_SY_OPEN_SQL_DB

Date and Time          14.01.2014 10:17:29

Short text                  SQL error "-1114" when accessing table "SRRELROLES".

What happened?       Error Text of the Database: "POS(1) Communication packet too small"

But after refresh UI and execute this SQL again, the dump not happens again.

After one day, everything looks appear again.

Is there anybody knows why?

My environment:

OS: Linux  x86_64

DB: MaxDB 7.8.02.033

NW: 720

Thanks & BR,

Tony