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Select from map with LowCardinality keys returns ClickHouseUnknownException: ClickHouse exception, message: Parse exception: ByteFragment

See original GitHub issue

Hello,

My setup Clickhouse server version 21.9.4 revision 54449 Clickhouse client version 21.9.4.35 JDBC version 0.3.1

Native client works

CREATE TABLE lcmap (m Map(LowCardinality(String), Int32)) ENGINE=Memory;
//...
INSERT INTO lcmap(m) VALUES ({'key1':1});

//...
select * from lcmap;
//...
┌─m──────────┐
│ {'key1':1} │
└────────────

But when I try to execute select * from lcmap; in Datagrip I get

<failed to load>
ru.yandex.clickhouse.except.ClickHouseUnknownException: ClickHouse exception, message: Parse exception: ByteFragment{[{'key1':1}], start=0, len=10}; null
	at ru.yandex.clickhouse.response.ClickHouseResultSet.getObject(ClickHouseResultSet.java:648)
	in JdbcHelperImpl.getObject(JdbcHelperImpl.java:321)
Caused by: java.lang.NullPointerException
	at java.base/java.util.Objects.requireNonNull(Objects.java:221)
	at ru.yandex.clickhouse.response.parser.ClickHouseMapParser.parse(ClickHouseMapParser.java:119)
	at ru.yandex.clickhouse.response.parser.ClickHouseMapParser.parse(ClickHouseMapParser.java:17)
	at ru.yandex.clickhouse.response.ClickHouseResultSet.getObject(ClickHouseResultSet.java:749)
	at ru.yandex.clickhouse.response.ClickHouseResultSet.getObject(ClickHouseResultSet.java:642)
	... 21 more

Issue Analytics

State:
Created 2 years ago
Comments:5

Top GitHub Comments

1reaction

zhicwucommented, Oct 5, 2021

Sorry I’m in the middle of merging new gRPC client into develop branch. After which, I’ll create another pull request by updating JDBC driver, clickhouse-jdbc module to be more specific, to use the new client in order to support more data types.

If you’re familiar with Java, you may play with the new client in these two days to explore what’s coming next.

1reaction

zhicwucommented, Oct 5, 2021

Thanks for reporting the issue. The driver does not support nested data types very well at this point. It understands Map(String, Int32) but not Map(LowCardinality(String), Int32), Map(String, Nullable(Int32)), or Map<String, Tuple(Int32, Array())>. Actually these cases work in an in-development version, so I believe this will be addressed in next release.

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