Antalya 26.6: Added support for alter add column with first/after

[subkanthi]

closes: #2091

Changelog category (leave one):

• Bug Fix (user-visible misbehavior in an official stable release)

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Added support for the FIRST and AFTER clauses with ALTER TABLE ADD COLUMN and ALTER TABLE MODIFY COLUMN for Iceberg tables (DataLakeCatalog).

CI/CD Options

Exclude tests:

• Fast test
• Integration Tests
• Stateless tests
• Stateful tests
• Unit tests
• Performance tests
• Aarch64 tests
• All with ASAN
• All with TSAN
• All with MSAN
• All with UBSAN
• All with Coverage
• All Regression
• Disable CI Cache

Regression jobs to run:

• Fast suites (mostly <1h)
• Aggregate Functions (2h)
• Alter (1.5h)
• Benchmark (30m)
• CAS (content-addressed storage; Antalya only)
• ClickHouse Keeper (1h)
• Iceberg (2h)
• LDAP (1h)
• OAuth (5m)
• Parquet (1.5h)
• RBAC (1.5h)
• SSL Server (1h)
• S3 (2h)
• S3 Export (2h)
• Swarms (30m)
• Tiered Storage (2h)

[github-actions]

Workflow [PR], commit [d9e23e0]

[subkanthi]

 set allow_insert_into_iceberg=1;

SET allow_insert_into_iceberg = 1

Query id: a24c0e73-e0cb-4a2b-9f38-a003b769a98e

Ok.

0 rows in set. Elapsed: 0.007 sec. 

Ubuntu-2404-noble-amd64-base :) alter table ice.`flowers.sample` add column value1 Nullable(Int64) first;

ALTER TABLE ice.`flowers.sample`
    (ADD COLUMN `value1` Nullable(Int64) FIRST )

Query id: a83c2a54-6343-4114-a876-655889a30e9e

Ok.

0 rows in set. Elapsed: 0.182 sec. 

Ubuntu-2404-noble-amd64-base :) show create table ice.`flowers.sample`;

SHOW CREATE TABLE ice.`flowers.sample`

Query id: 0e533740-a3f7-435e-bfa8-b0fddfaae688

   ┌─statement─────────────────────────────────────────────────────────┐
1. │ CREATE TABLE ice.`flowers.sample`                                ↴│
   │↳(                                                                ↴│
   │↳    `value1` Nullable(Int64),                                    ↴│
   │↳    `value` Nullable(Int64),                                     ↴│
   │↳    `boolean_col` Nullable(Bool),                                ↴│
   │↳    `dec_col_2` Nullable(Decimal(10, 2)),                        ↴│
   │↳    `value2` Nullable(Int64),                                    ↴│
   │↳    `value3` Nullable(Int64)                                     ↴│
   │↳)                                                                ↴│
   │↳ENGINE = Iceberg('http://localhost:9000/bucket1/flowers/sample/') │
   └───────────────────────────────────────────────────────────────────┘

1 row in set. Elapsed: 0.017 sec. 

[subkanthi]

alter table ice.`flowers.sample` modify column value2 Nullable(Int64) first;

ALTER TABLE ice.`flowers.sample`
    (MODIFY COLUMN `value2` Nullable(Int64) FIRST )

Query id: a96ecd40-d7c7-4e4d-b6b9-1a62453b4418

Connecting to database ice at localhost:9008 as user default.
Connected to ClickHouse server version 26.6.2.

Ok.

0 rows in set. Elapsed: 0.258 sec. 

Ubuntu-2404-noble-amd64-base :) show create table ice.`flowers.sample`;

SHOW CREATE TABLE ice.`flowers.sample`

Query id: 901ee53f-8b02-4b95-b4d7-e2de4a8992f1

   ┌─statement─────────────────────────────────────────────────────────┐
1. │ CREATE TABLE ice.`flowers.sample`                                ↴│
   │↳(                                                                ↴│
   │↳    `value2` Nullable(Int64),                                    ↴│
   │↳    `value1` Nullable(Int64),                                    ↴│
   │↳    `value` Nullable(Int64),                                     ↴│
   │↳    `boolean_col` Nullable(Bool),                                ↴│
   │↳    `dec_col_2` Nullable(Decimal(10, 2)),                        ↴│
   │↳    `value11` Nullable(Int64),                                   ↴│
   │↳    `value3` Nullable(Int64),                                    ↴│
   │↳    `value6` Nullable(Int64)                                     ↴│
   │↳)                                                                ↴│
   │↳ENGINE = Iceberg('http://localhost:9000/bucket1/flowers/sample/') │
   └───────────────────────────────────────────────────────────────────┘

1 row in set. Elapsed: 0.013 sec. 

[DimensionWieldr]

CI triage

Not caused by this PR. Iceberg FIRST/AFTER tests passed (test_writes_modify_column_position.py, Iceberg regression, unit tests). Run 33461281948 / SHA d9e23e0e.

Category	What
This PR	none
Pre-existing flaky	test_concurrent_create_drop_race_condition (timeout; 26 fails / 9 PRs upstream); 00661_optimize_final…, 01055_compact_parts (0 fails on diagnosis); 02265_column_ttl (CAS S3 Code 210)
Infrastructure	asan session-timeout (3/8: 496 passed, 0 failed); Spark iceberg cluster Connection refused (schema_inference); fake GCS UNCERTAIN (test_cas_gcs); tiered_storage docker teardown hang; 5h cancelled CAS jobs; empty 10‑min GitHub placeholders
Unrelated (test suite)	settings snapshot missing export_merge_tree_part_ignore_extra_source_columns / export_merge_tree_part_schema_match_mode after #2220 — will fail every antalya-26.6 PR until the 26.6_antalya snapshot is updated

Approve from a #2289 perspective. Optional: rerun integration 3/8 and 4/8; fix settings snapshots in clickhouse-regression separately.

[DimensionWieldr]

Tests in Altinity/clickhouse-regression@a7fcec8 for FIRST / AFTER are passing on Glue and Ice rest catalogs.

LGTM