Re: FOR PORTION OF does not recompute GENERATED STORED columns that depend on the range column

On Mon, Apr 20, 2026 at 4:10 AM Paul A Jungwirth
<pj(at)illuminatedcomputing(dot)com> wrote:
>
> v5 attached.
>
v5 will cause a segfault.

+ /*
+ * For UPDATE ... FOR PORTION OF, the range column is being modified
+ * (narrowed via intersection), but it is not included in updatedCols
+ * because the user does not need UPDATE permission on it. Now manualy
+ * add it to updatedCols. Since ri_forPortionOf->fp_rangeAttno is already
+ * mapped for the child partition, we have to add it after the mapping just
+ * above. Also that makes it unsafe to mutate perminfo. XXX: Always add the
+ * unmapped attno instead (before mapping), and mutate perminfo, to avoid
+ * repeated allocations?
+ */
+ if (relinfo->ri_forPortionOf)
+ {
+ AttrNumber rangeAttno = relinfo->ri_forPortionOf->fp_rangeAttno;
+
+ if (!bms_is_member(rangeAttno - FirstLowInvalidHeapAttributeNumber,
+ updatedCols))
+ {
+ MemoryContext oldContext;
+
+ oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
+
+ updatedCols =
+ bms_add_member(updatedCols,
+ rangeAttno - FirstLowInvalidHeapAttributeNumber);
+
+ MemoryContextSwitchTo(oldContext);
+ }
+ }
+
+ return updatedCols;

+ updatedCols =
+ bms_add_member(updatedCols,
+ rangeAttno - FirstLowInvalidHeapAttributeNumber);

Here, use "perminfo->updatedCols" not "updatedCols", otherwise segfault.
The attached diff based on v5, fixes this issue.

+ALTER TABLE temporal_partitioned_3 ADD COLUMN range_len int GENERATED
ALWAYS AS (upper(valid_at) - lower(valid_at)) STORED;
Slightly refactoring the tests will allow for easier comparison of
range_len values.

--
jian
https://www.enterprisedb.com/