JDBC Driver marks Nullable Column as non-nullable

Hello,

This is my first question here, so apologies in advance if I missed any information and pls let me know if more info is needed.

We have a table with a column defined as such

 `my_custom_column`                       SimpleAggregateFunction(anyLast, Nullable(DateTime64(3, 'UTC'))),

However, when we attempt to write a row with the column set to a null value, we are getting errors and on debugging it seems like the ClickhouseColumn is set as nullable=false.

Caused by: java.sql.SQLException: Cannot set null to non-nullable column #1 [my_custom_column SimpleAggregateFunction(anyLast, Nullable(DateTime64(3, 'UTC')))]
	at com.clickhouse.jdbc.SqlExceptionUtils.clientError(SqlExceptionUtils.java:73)
	at com.clickhouse.jdbc.internal.InputBasedPreparedStatement.addBatch(InputBasedPreparedStatement.java:328)
	at com.clickhouse.jdbc.internal.InputBasedPreparedStatement.executeAny(InputBasedPreparedStatement.java:110)
	at com.clickhouse.jdbc.internal.InputBasedPreparedStatement.executeLargeUpdate(InputBasedPreparedStatement.java:185)
	at com.clickhouse.jdbc.internal.AbstractPreparedStatement.executeUpdate(AbstractPreparedStatement.java:135)
	at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeUpdate(ProxyPreparedStatement.java:61)
	at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeUpdate(HikariProxyPreparedStatement.java)
	at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:197)

I am able to insert a NULL value for the column via the clickhouse client CLI - so this seems like an issue with the Java driver. More specifically - an error parsing the column definition from the Database.

Can you please help? Thanks!

[zhicwu]

Good point but LowCardinality is simply ignored(because the column only keeps one single value?):

-- [NULL]	LowCardinality(Nullable(String))
select null::LowCardinality(Nullable(String)) v , toTypeName(v) t

-- [NULL]	Nullable(SimpleAggregateFunction(anyLast, String))
select anyLastSimpleState(v) x, toTypeName(x) y
from (select null::LowCardinality(Nullable(String)) v , toTypeName(v) t)

Having said that, I’ve just verified the local changes and it works well 😃

[zhicwu]

Hi @nym3r0s, thanks for the bug report. For SimpleAggregateFunction, we should use the inner type, so it’s actually nullable column in this case.