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https://github.com/Ecwid/clickhouse-client
Java/Kotlin client for ClickHouse
https://github.com/Ecwid/clickhouse-client
clickhouse clickhouse-client java kotlin
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Java/Kotlin client for ClickHouse
- Host: GitHub
- URL: https://github.com/Ecwid/clickhouse-client
- Owner: Ecwid
- License: apache-2.0
- Created: 2019-01-11T03:24:08.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2024-05-22T11:33:56.000Z (4 months ago)
- Last Synced: 2024-06-17T19:02:01.436Z (3 months ago)
- Topics: clickhouse, clickhouse-client, java, kotlin
- Language: Kotlin
- Homepage:
- Size: 301 KB
- Stars: 25
- Watchers: 20
- Forks: 8
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# clickhouse-client
Java/Kotlin client for ClickHouse (https://clickhouse.com)
## How to use
There are three different clients, from raw low-level client to simple object mapper.
### Mapped client (transparently converts response rows into your POJO)
```java
HttpTransport httpTransport = new ApacheHttpClientTransport();
ClickHouseMappedClient client = new ClickHouseMappedClient(httpTransport);
try (MappedResponse response = client.select("http://localhost:8123", "SELECT * FROM user", User::convert)) {
for (User user : response) {
System.out.println(user);
}
}
```
Class `User` and `convert` function can be something like this
```java
class User {
private final String name;
private final int age;
public User(String name, int age) {
this.name = name;
this.age = age;
}
public static User convert(TypedRow row) {
String name = row.getString("name");
int age = row.getInt8("age");
return new User(name, age);
}
}
```
### Typed client (looks like JDBC ResultSet class)
```java
HttpTransport httpTransport = new ApacheHttpClientTransport();
ClickHouseTypedClient client = new ClickHouseTypedClient(httpTransport);
try (TypedResponse response = client.select("http://localhost:8123", "SELECT * FROM table")) {
for (TypedRow typedRow : response) {
int firstValue = typedRow.getInt32(1);
Date secondValue = typedRow.getDateTime(2);
List thirdValue = typedRow.getInt32Array(3);
System.out.println(firstValue + ":" + secondValue + ":" + thirdValue);
}
}
```
### Raw client (very low level, use if you want to control everything)
```java
HttpTransport httpTransport = new ApacheHttpClientTransport();
ClickHouseRawClient client = new ClickHouseRawClient(httpTransport);
try (RawResponse response = client.select("http://localhost:8123", "SELECT * FROM table")) {
for (RawRow row : response) {
System.out.println(row);
}
}
```
## How to add clickhouse-client into your project
### Gradle
```
compile "com.ecwid.clickhouse:clickhouse-client:0.15.0"
```
### Maven
```
com.ecwid.clickhouse
clickhouse-client
0.15.0
```
## How to enable metrics in clickhouse-client
### Use prometheus metrics
Add prometheus metric dependency to your project
gradle
```
compile "io.prometheus:prometheus-metrics-core:1.2.0"
```
Inject metrics collector on instantiate client
```java
HttpTransport httpTransport = new ApacheHttpClientTransport();
ClickHouseMappedClient client = new ClickHouseMappedClient(httpTransport, DefaultMetrics.INSTANCE.getPROMETHEUS());
```
### Use custom metrics collector
Add implementation of `com.ecwid.clickhouse.metrics.Metrics` interface
```java
import com.ecwid.clickhouse.metrics.Metrics;
import org.jetbrains.annotations.NotNull;
public class DummyMetrics implements Metrics {
@Override
public void measureRequest(@NotNull String host, int statusCode) {
// Measure request to host with received http status code
}
@NotNull
@Override
public AutoCloseable startRequestTimer(@NotNull String host) {
// start measuring request
final long startedAt = System.currentTimeMillis();
return new AutoCloseable() {
@Override
public void close() throws Exception {
final long completedAt = System.currentTimeMillis();
// measure request time to host
}
};
}
}
```
And use it on instantiate client:
```java
HttpTransport httpTransport = new ApacheHttpClientTransport();
ClickHouseMappedClient client = new ClickHouseMappedClient(httpTransport, new DummyMetrics());
```