Background

v0.3.2 was a minor release scheduled to be released months ago, but now it's a complete rewrite mainly for two reasons:

1. decoupling(see Proposal of restructuring code (RFC) #570 for details)

   • Java client is async and lightweight
   • JDBC driver is built on top of Java client

2. switching data format to RowBinary to fix issues and improve performance
   Benchmark results...

   0.3.2-test1...

   • clickhouse-grpc-jdbc and clickhouse-http-jdbc are new JDBC driver(0.3.2) using RowBinary data format
   • clickhouse-jdbc is the old JDBC driver(0.3.1-patch) based on TabSeparated
   • clickhouse-native-jdbc is ClickHouse-Native-JDBC 2.6.0
     Benchmark settings: thread=1, sampleSize=100000, fetchSize=10000, mode=throughput(ops/s).
     
   0.3.2-test3...

   Unlike previous round of testing, ClickHouse container is re-created a few minutes before benchmarking each driver.

   • Single thread
     • Comparison
       
       Note: HttpClient is async(uses more than one thread in runtime); gRPC uses gzip(why?) which is slower than lz4.
     • VM utilization
       
       Note: on client side, the new driver consumes less memory and CPU than others, BUT higher CPU on server side(due to overhead of http protocol?).
   • 4 threads

     • Comparison
       

     • VM utilization
       

   0.3.2...

   

   Query performance is similar as shown in 0.3.2-test3 so this time we only focus on insertion.
   
   Note: gRPC does not support LZ4 compression so we use GZIP in the test.

   • Single thread
     
   • 4 threads
     

0.3.2-test1, 0.3.2-test2, and 0.3.2-test3 are pre-release for public testing.

Downloads

Maven dependency:

<dependency>
    <!-- will stop using group id "ru.yandex.clickhouse" starting from 0.4.0  -->
    <groupId>com.clickhouse</groupId>
    <!-- or clickhouse-grpc-client to use gRPC client  -->
    <artifactId>clickhouse-http-client</artifactId>
    <version>0.3.2-test3</version>
</dependency>

To download JDBC drivers:

Note: the first two are recommended. grpc is experimental so you'd better use http.

Known Issues

• new driver(com.clickhouse.jdbc.ClickHouseDriver) does not work with version before 21.3
• java.io.IOException: HTTP/1.1 header parser received no bytes when using JDK 11+ and http_connection_provider is set to HTTP_CLIENT
• RESOURCE_EXHAUSTED: Compressed gRPC message exceeds maximum size - increase max_inbound_message_size to resolve
• select 1 format JSON works in http but not grpc, because grpc client is not aware of response format
• insert into table values(?, ?) is slow in batch mode - try insert into table select c2,c3 from input('c1 String, c2 UInt8, c3 Nullable(UInt32)') instead
• use_time_zone and use_server_time_zone_for_dates properties do not work
• no table/index show up under jdbc(*) database
• roaringbitmap is not included in the shaded jar

Key Changes

• Java client and JDBC driver are now in different modules, along with JPMS support
• Replaced data format from TabSeparated to RowBinary
• Support more data types including Date32, Geo types, and mixed use of nested types
• JDBC connection URL now supports abbrebation, protocol and optional port
  • jdbc:ch://localhost is same as jdbc:clickhouse:http://localhost:8123
  • jdbc:ch:grpc://localhost/db is same as jdbc:clickhouse:grpc://localhost:9100/db
• New JDBC driver class is com.clickhouse.jdbc.ClickHouseDriver(will remove ru.yandex.clickhouse.ClickHouseDriver starting from 0.4.0)
• JDBC connection properties are simplified
  • use custom_http_headers and custom_http_params for customization - won't work for grpc client
  • jdbcCompliant(defaults to true) to support fake transaction and standard synchronous UPDATE and DELETE statements
  • typeMappings to customize type mapping(e.g. DateTime=java.lang.String,DateTime32=java.lang.String)

Some more details can be found at #736, #747, #769, and #777.