Bogus SqlParser warning for valid ALTER TABLE .. ALTER COLUMN syntax

[lukaseder]

Steps to reproduce

try (Statement s = connection.createStatement()) {
    try {
        s.executeUpdate("create table t (i int, j int, primary key (i)) engine = MergeTree()");
        s.executeUpdate("alter table t alter column j default 1");
    }
    finally {
        s.executeUpdate("drop table if exists t");
    }
}

The syntax is perfectly fine:

• https://clickhouse.com/docs/sql-reference/statements/alter/column#modify-column

Error Log or Exception StackTrace

12:35:58,252  WARN [SqlParser                     ] - SQL syntax error at line: 1, pos: 14, mismatched input 'alter' expecting {ADD, ATTACH, CLEAR, COMMENT, DELETE, DETACH, DROP, FREEZE, MATERIALIZE, MODIFY, MOVE, ON, REMOVE, RENAME, REPLACE, UPDATE}

Expected Behaviour

No log entries

Configuration

Environment

• Client version: com.clickhouse:clickhouse-jdbc:0.9.2
• Language version: OpenJDK Runtime Environment Temurin-21.0.7+6 (build 21.0.7+6-LTS)
• OS: Microsoft Windows [Version 10.0.26100.4946]

ClickHouse Server

• ClickHouse Server version: 25.4.4.25

[larshelge]

I am seeing the same for create table statements.

• WARN 2025-09-24T15:26:14,873 SQL syntax error at line: 1, pos: 72, mismatched input 'not' expecting {',', ')'} (SqlParser [pool-4-thread-1]) UID:qgoKKOXuRSh

It certainly appears to not indicate a real issue, but is somewhat confusing and noisy.

[chernser]

Good day, @lukaseder !

While working on this issue I've found that this form of SQL is not supported by ClickHouse at least it causes error with clickhouse-client:

DESCRIBE TABLE t2

Query id: 2c20faae-2e16-449f-83e2-a7f4a2366ca6

   ┌─name─┬─type────┬─default_type─┬─default_expression─┬─comment─┬─codec_expression─┬─ttl_expression─┐
1. │ v    │ Float32 │              │                    │         │                  │                │
   └──────┴─────────┴──────────────┴────────────────────┴─────────┴──────────────────┴────────────────┘

1 row in set. Elapsed: 0.001 sec. 

0d7376d76759 :) alter table t2 alter column v Int32

Syntax error: failed at position 31 (Int32):

alter table t2 alter column v Int32

Expected one of: token sequence, Dot, token, REMOVE, MODIFY SETTING, RESET SETTING, DEFAULT, MATERIALIZED, EPHEMERAL, ALIAS, AUTO_INCREMENT, PRIMARY KEY, COMMENT, CODEC, TYPE

However another form with MODIFY COLUMN works.

0d7376d76759 :) alter table t2 modify column v Int32

ALTER TABLE t2
    (MODIFY COLUMN `v` Int32)

Query id: e794f4a2-2a0f-44ec-801b-05c131ef8716

Ok.

Syntax is described in documentation https://clickhouse.com/docs/sql-reference/statements/alter/column#modify-column. Will this specifics be handled by JOOQ ?

Thanks!

[lukaseder]

Thanks for your message, @chernser. jOOQ actually does generate MODIFY COLUMN. I'm not sure anymore why I reported ALTER COLUMN instead. It's documented as an alternative:

https://clickhouse.com/docs/sql-reference/statements/alter/column#modify-column

Though, the TYPE keyword seems mandatory according to the docs. But it does seem to work also without the TYPE keyword in Dbeaver:

In any case, the specific error reported by the JDBC driver doesn't seem correct. There is some set of ALTER TABLE .. ALTER COLUMN syntax that should be accepted, according to the docs.

[chernser]

Verified in com.clickhouse.jdbc.internal.BaseSqlParserFacadeTest#testStatementsForResultSet