DIFF TABLE does not support HEAP-organized tables

[Poseidon-fan]

Description

The DIFF TABLE statement fails when executed on a table created with ORGANIZATION = HEAP.

Steps to Reproduce

1. Create a source table with ORGANIZATION = HEAP:

   create table t_heap_src (
     id int,
     name varchar(50),
     score int
   ) ORGANIZATION = HEAP;

2. Attempt to execute a DIFF TABLE statement (the specific fork t... command from the original report is incomplete).
3. The operation fails with an error.

Impact

Users cannot use the DIFF TABLE feature to compare or merge data for tables using the HEAP storage organization.