Preserve explicitly enforced zonemaps when partition keys are changed or dropped.

Detail name	Value
Changelog Number	30918
Type	Bug
Status	Resolved
Affected Versions	Exasol 8.18.0, Exasol 8.29.0, Exasol 2025.1.0, Exasol 2026.1.0
Fix Versions	Exasol 2026.1.1, Exasol 2025.1.14
Resolution Date	2026-08-06

Description

Dropping or changing the partition keys of a table could remove zonemaps that were explicitly created using ENFORCE ZONEMAP.

This happened when all the following criteria were met:

• The table was partitioned.
• One or more zonemaps had been explicitly created using ENFORCE ZONEMAP.
• The partition keys were changed or dropped using ALTER TABLE.

Example

CREATE OR REPLACE TABLE T1 AS
SELECT
    range_value AS i,
    4 * range_value AS j,
    100000 - 2 * range_value AS k
FROM VALUES BETWEEN 1 AND 10000;

ALTER TABLE T1 PARTITION BY i, j;

ENFORCE ZONEMAP ON T1(k);

SELECT COLUMN_NAME, COLUMN_IS_ZONEMAPPED
FROM SYS.EXA_ALL_COLUMNS
WHERE COLUMN_SCHEMA = CURRENT_SCHEMA
  AND COLUMN_TABLE = 'T1';

-- Observed before ALTER TABLE:
-- K: TRUE

ALTER TABLE T1 DROP PARTITION KEYS;

SELECT COLUMN_NAME, COLUMN_IS_ZONEMAPPED
FROM SYS.EXA_ALL_COLUMNS
WHERE COLUMN_SCHEMA = CURRENT_SCHEMA
  AND COLUMN_TABLE = 'T1';

-- Expected: K remains TRUE.
-- Observed before the fix: K becomes FALSE.

Workaround

Recreate the required zonemaps after changing or dropping partition keys using ENFORCE ZONEMAP.

ALTER TABLE T1 DROP PARTITION KEYS;

ENFORCE ZONEMAP ON T1(k);

Fix

Explicitly enforced zonemaps are now preserved when partition keys are changed or dropped. Only zonemaps associated with partition columns are updated automatically.