NullPointerException when executing a query with a JOIN to PostgreSQL.

[ruslanen]

Hi. I use clickhouse-jdbc-bridge with postgresql driver.
Recently I have tried to execute query with JOIN, but found an error NullPointerException here.

It is easy to repeat a problem:

1. Create tables in PostgreSQL:

create table brands (
    brandname text not null,
    key bigint not null
);
insert into brands values ('Contoso',1), ('Adventure Works', 2), ('Litware', 3);

create table facts (
    salesamount numeric,
    key bigint not null
);
insert into facts values (100,1), (200, 2), (300, 4);

2. Execute query in ClickHouse:

select *
from jdbc(
    'jdbc:postgresql://localhost:5432/postgres?user=postgres&password=postgres',
    'postgres',
    'select brandname, brands.key as "bk", salesamount, facts.key as "fk"
     from brands
     full join facts on brands.key = facts.key;');

3. You will get an error:

May 18, 2023 10:38:33 AM com.clickhouse.jdbcbridge.core.NamedDataSource executeQuery
INFO: Executing query(schema=[postgres]):
select brandname, brands.key as "bk", salesamount, facts.key as "fk"
     from brands
     full join facts on brands.key = facts.key;
May 18, 2023 10:38:33 AM com.clickhouse.jdbcbridge.JdbcBridgeVerticle errorHandler
SEVERE: Failed to respond
java.lang.NullPointerException
	at java.base/java.util.Objects.requireNonNull(Objects.java:208)
	at com.clickhouse.jdbcbridge.core.ByteBuffer.writeString(ByteBuffer.java:644)
	at com.clickhouse.jdbcbridge.impl.JdbcDataSource$ResultSetReader.read(JdbcDataSource.java:258)
	at com.clickhouse.jdbcbridge.core.DataTableReader.process(DataTableReader.java:176)
	at com.clickhouse.jdbcbridge.impl.JdbcDataSource.writeQueryResult(JdbcDataSource.java:720)
	at com.clickhouse.jdbcbridge.core.NamedDataSource.executeQuery(NamedDataSource.java:552)
	at com.clickhouse.jdbcbridge.JdbcBridgeVerticle.handleQuery(JdbcBridgeVerticle.java:488)
	at io.vertx.ext.web.impl.BlockingHandlerDecorator.lambda$handle$0(BlockingHandlerDecorator.java:48)
	at io.vertx.core.impl.ContextImpl.lambda$executeBlocking$2(ContextImpl.java:313)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.base/java.lang.Thread.run(Thread.java:832)

clickhouse-jdbc-bridge relies on the fact that there will be no NULLs, but they are (because of JOIN behavior).

Some info:

• clickhouse-jdbc-bridge: master branch (9ecc9c5)
• postgresql-42.3.4.jar.

[ruslanen]

@zhicwu Hello.
There has been no activity in the repo for a very long time.
Is it still supported?