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Regression for nullable metadata with JDBC client between 0.9.1 and 0.9.2 #2586
Description
Description
Between 0.9.1 and 0.9.2, there was a regression around the metadata for nullability in the JDBC driver.
Note that this affects only the JDBC client, not the Java HTTP client
Steps to reproduce
- Create table with nullable column
- Run the sample code
Code Example
I have the following table:
create table
`nullable_key`
(
`key_1` Nullable(Int64),
`key_2` Nullable(Int64),
`value` String NOT NULL
)
ENGINE = MergeTree()
ORDER BY tuple()
;
INSERT INTO
`nullable_key`
VALUES
(1, null, 'value_1_null'),
(1, 1, 'value_1_1'),
(2, 2, 'value_2_2'),
(null, 2, 'value_null_2'),
(null, null, 'value_null_null');
I query said table the following way:
@Test
void testTypes() throws Exception {
String databaseName = "tck_db_v1";
String tableName = "nullable_key";
Client client = CONFIG.getClient();
TableSchema schemaFromHttpClient = client.getTableSchema(tableName);
System.out.println("Schema from ClickHouse HTTP client:" + schemaFromHttpClient);
for (var col : schemaFromHttpClient.getColumns()) {
System.out.println(col.getColumnName() + " is nullable: " + col.isNullable());
}
final var jdbcUrl = "jdbc:clickhouse:"
+ CONFIG.getClient().getEndpoints().iterator().next()
+ "/" + databaseName;
final Properties properties = new Properties();
properties.put("user", "default");
properties.put("password", "");
System.out.println("JDBC URL: " + jdbcUrl);
try (Connection connection = DriverManager.getConnection(jdbcUrl, properties)) {
final ResultSet columns = connection.getMetaData()
.getColumns(
null,
convertToPattern(databaseName),
convertToPattern(tableName),
null);
while (columns.next()) {
final String name = columns.getString("COLUMN_NAME");
final boolean isNullable = columns.getBoolean("NULLABLE");
System.out.println(name + " nullable: " + isNullable);
}
}
}
private static String convertToPattern(String likePattern) {
return likePattern.replace("_", "\\_");
}On 0.9.1, this returns:
Schema from ClickHouse HTTP client:TableSchema{tableName='nullable_key', databaseName='tck_db_v1', columns=[key_1 Nullable(Int64), key_2 Nullable(Int64), value String], colIndex={key_1=0, key_2=1, value=2}, hasDefaults=false}
key_1 is nullable: true
key_2 is nullable: true
value is nullable: false
JDBC URL: jdbc:clickhouse:http://localhost:32859/tck_db_v1
key_1 nullable: true
key_2 nullable: true
value nullable: false
On 0.9.2, this returns:
Schema from ClickHouse HTTP client:TableSchema{tableName='nullable_key', databaseName='tck_db_v1', columns=[key_1 Nullable(Int64), key_2 Nullable(Int64), value String], colIndex={key_1=0, key_2=1, value=2}, hasDefaults=false}
key_1 is nullable: true
key_2 is nullable: true
value is nullable: false
JDBC URL: jdbc:clickhouse:http://localhost:32859/tck_db_v1
key_1 nullable: false
key_2 nullable: false
value nullable: false
On 0.9.2, the value for plain JDBC differs from the HTTP client, and is also a regression vs 0.9.1
Activity
chernser commentedon Sep 16, 2025
@NathanEckert
thank you for the feedback!
This looks like problem in reading int32 values as boolean. We will fix it.