Iceberg DataLakeCatalog: ALTER DELETE fails with Metadata is not initialized (LOGICAL_ERROR)

Describe the bug

ALTER TABLE … DELETE against an Iceberg table accessed through DataLakeCatalog fails with:

Code: 49. DB::Exception: Metadata is not initialized. (LOGICAL_ERROR)

The same delete works against a path-based ENGINE = Iceberg(...) table. INSERT into the same DataLakeCatalog table works when allow_insert_into_iceberg = 1.

How to reproduce

Requires a REST Iceberg catalog (e.g. ice-rest-catalog) with an existing merge-on-read table, then:

SET allow_experimental_database_iceberg = 1;
SET allow_insert_into_iceberg = 1;

CREATE DATABASE datalake_db
ENGINE = DataLakeCatalog('http://ice-rest-catalog:5000', 'minio_key', 'minio_secret')
SETTINGS
    catalog_type = 'rest',
    storage_endpoint = 'http://minio:9000/warehouse',
    warehouse = 's3://bucket1/',
    auth_header = 'Authorization: Bearer foo';

-- Assume catalog table `ns.t` already exists (format-version 2, write.delete.mode = merge-on-read)
-- and has been seeded with rows (id, data).

-- SELECT / INSERT via catalog work; DELETE does not:
ALTER TABLE datalake_db.`ns.t` DELETE WHERE id <= 2;

Observed error:

Code: 49. DB::Exception: Metadata is not initialized. (LOGICAL_ERROR)

By contrast, the path-based engine succeeds:

CREATE TABLE iceberg_path
ENGINE = Iceberg('http://minio:9000/warehouse/data/ns/t', 'minio_key', 'minio_secret');

SET allow_insert_into_iceberg = 1;
ALTER TABLE iceberg_path DELETE WHERE id <= 2;  -- OK, writes position deletes

Observed on 26.3.13.20001.altinityantalya.

Expected behavior

With allow_insert_into_iceberg = 1, ALTER TABLE <datalake_db>.'ns.t' DELETE WHERE … should write Iceberg position deletes and commit through the catalog, same as ENGINE = Iceberg.

Same bug was already reported and fixed upstream:

supportsDelete in DataLakeConfiguration throws LOGICAL_ERROR on freshly-attached data lake table with uninitialized metadata ClickHouse/ClickHouse#104891 — `supportsDelete` throws `Metadata is not initialized` (fixed by Fix Metadata is not initialized on DELETE FROM for data lakes ClickHouse/ClickHouse#104917; merged into `26.6.1.286`, backported to `26.5.3.12`, `26.4.5.13`)
Related: Logical error: 'Metadata is not initialized' ClickHouse/ClickHouse#96806, DataLakeCatalog: Logical Error in ALTER TABLE query ClickHouse/ClickHouse#86024

26.3.13.20001.altinityantalya still hits the bug on DataLakeCatalog ALTER DELETE (upstream fix is on 26.4+).

@DimensionWieldr

@DimensionWieldr tried this on #2157

select * from ice.`flowers.sample`;

SELECT *
FROM ice.`flowers.sample`

Query id: fb087678-c4db-44d3-9434-9d223d2f762d

    ┌─value─┐
 1. │     1 │
 2. │     2 │
 3. │     3 │
 4. │     4 │
 5. │     5 │
 6. │     6 │
 7. │     7 │
 8. │     8 │
 9. │     9 │
10. │    10 │
    └───────┘

alter table ice.`flowers.sample` delete where value=1;

ALTER TABLE ice.`flowers.sample`
    (DELETE WHERE value = 1)

Query id: 6b5adcf9-574f-4fe6-9983-a9b4ab01da55

Ok.

0 rows in set. Elapsed: 0.401 sec.

select * from ice.`flowers.sample`;

SELECT *
FROM ice.`flowers.sample`

Query id: 8d10dad9-f1fc-4ab0-b6d2-e7492b75ac5e

   ┌─value─┐
1. │     2 │
2. │     3 │
3. │     4 │
4. │     5 │
5. │     6 │
6. │     7 │
7. │     8 │
8. │     9 │
9. │    10 │
   └───────┘

9 rows in set. Elapsed: 0.042 sec.

Fixed by #2157 , version 26.6, no need to backport to older versions.

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Iceberg DataLakeCatalog: ALTER DELETE fails with Metadata is not initialized (LOGICAL_ERROR) #2136

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Iceberg DataLakeCatalog: ALTER DELETE fails with Metadata is not initialized (LOGICAL_ERROR) #2136

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DimensionWieldr commented on Jul 31, 2026

subkanthi commented on Aug 7, 2026

DimensionWieldr commented on Aug 21, 2026

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