158 lines
5.4 KiB
Markdown
158 lines
5.4 KiB
Markdown
---
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id: human-readable-byte
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title: "Human-readable Byte Configuration Reference"
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---
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<!--
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~ Licensed to the Apache Software Foundation (ASF) under one
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~ or more contributor license agreements. See the NOTICE file
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~ distributed with this work for additional information
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~ regarding copyright ownership. The ASF licenses this file
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~ to you under the Apache License, Version 2.0 (the
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~ "License"); you may not use this file except in compliance
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~ with the License. You may obtain a copy of the License at
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~
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~ http://www.apache.org/licenses/LICENSE-2.0
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~
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~ Unless required by applicable law or agreed to in writing,
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~ software distributed under the License is distributed on an
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~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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~ specific language governing permissions and limitations
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~ under the License.
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-->
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This page documents configuration properties related to bytes.
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These properties can be configured through 2 ways:
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1. a simple number in bytes
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2. a number with a unit suffix
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## A number in bytes
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Given that cache size is 3G, there's a configuration as below
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```properties
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# 3G bytes = 3_000_000_000 bytes
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druid.cache.sizeInBytes=3000000000
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```
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## A number with a unit suffix
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When you have to put a large number for some configuration as above, it is easy to make a mistake such as extra or missing 0s. Druid supports a better way, a number with a unit suffix.
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Given a disk of 1T, the configuration can be
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```properties
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druid.segmentCache.locations=[{"path":"/segment-cache-00","maxSize":"1t"},{"path":"/segment-cache-01","maxSize":"1200g"}]
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```
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Note: in above example, both `1t` and `1T` are acceptable since it's case-insensitive.
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Also, only integers are valid as the number part. For example, you can't replace `1200g` with `1.2t`.
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### Supported Units
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In the world of computer, a unit like `K` is ambiguous. It means 1000 or 1024 in different contexts, for more information please see [Here](https://en.wikipedia.org/wiki/Binary_prefix).
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To make it clear, the base of units are defined in Druid as below
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| Unit | Description | Base |
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|---|---|---|
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| K | Kilo Decimal Byte | 1_000 |
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| M | Mega Decimal Byte | 1_000_000 |
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| G | Giga Decimal Byte | 1_000_000_000 |
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| T | Tera Decimal Byte | 1_000_000_000_000 |
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| P | Peta Decimal Byte | 1_000_000_000_000_000 |
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| KiB | Kilo Binary Byte | 1024 |
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| MiB | Mega Binary Byte | 1024 * 1024 |
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| GiB | Giga Binary Byte | 1024 * 1024 * 1024 |
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| TiB | Tera Binary Byte | 1024 * 1024 * 1024 * 1024 |
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| PiB | Peta Binary Byte | 1024 * 1024 * 1024 * 1024 * 1024 |
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Unit is case-insensitive. `k`, `kib`, `KiB`, `kiB` are all acceptable.
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Here are two examples
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```properties
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# 1G bytes = 1_000_000_000 bytes
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druid.cache.sizeInBytes=1g
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```
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```properties
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# 256MiB bytes = 256 * 1024 * 1024 bytes
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druid.cache.sizeInBytes=256MiB
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```
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## 配置文档
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本部分内容列出来了每一种Druid服务的所有配置项
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### 推荐的配置文件组织方式
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对于Druid的配置文件，一种推荐的结构组织方式为将配置文件放置在Druid根目录的`conf`目录下，如以下所示：
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```json
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$ ls -R conf
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druid
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conf/druid:
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_common broker coordinator historical middleManager overlord
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conf/druid/_common:
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common.runtime.properties log4j2.xml
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conf/druid/broker:
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jvm.config runtime.properties
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conf/druid/coordinator:
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jvm.config runtime.properties
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conf/druid/historical:
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jvm.config runtime.properties
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conf/druid/middleManager:
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jvm.config runtime.properties
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conf/druid/overlord:
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jvm.config runtime.properties
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```
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每一个目录下都有一个 `runtime.properties` 文件，该文件中包含了特定的Druid进程相关的配置项，例如 `historical`
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`jvm.config` 文件包含了每一个服务的JVM参数，例如堆内存属性等
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所有进程共享的通用属性位于 `_common/common.runtime.properties` 中。
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### 通用配置
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本节下的属性是应该在集群中的所有Druid服务之间共享的公共配置。
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#### JVM配置最佳实践
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在我们的所有进程中有四个需要配置的JVM参数
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1. `-Duser.timezone=UTC` 该参数将JVM的默认时区设置为UTC。我们总是这样设置，不使用其他默认时区进行测试，因此本地时区可能会工作，但它们也可能会发现奇怪和有趣的错误。要在非UTC时区中发出查询，请参阅 [查询粒度](../querying/granularity.md)
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2. `-Dfile.encoding=UTF-8` 这类似于时区，我们假设UTF-8进行测试。本地编码可能有效，但也可能导致奇怪和有趣的错误。
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3. `-Djava.io.tmpdir=<a path>` 系统中与文件系统交互的各个部分都是通过临时文件完成的，这些文件可能会变得有些大。许多生产系统都被设置为具有小的（但是很快的）`/tmp`目录，这对于Druid来说可能是个问题，因此我们建议将JVM的tmp目录指向一些有更多内容的目录。此目录不应为volatile tmpfs。这个目录还应该具有良好的读写速度，因此应该强烈避免NFS挂载。
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4. `-Djava.util.logging.manager=org.apache.logging.log4j.jul.LogManager` 这允许log4j2处理使用标准java日志的非log4j2组件（如jetty）的日志。
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#### 扩展
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#### 请求日志
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#### SQL兼容的空值处理
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### Master
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#### Coordinator
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#### Overlord
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### Data
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#### MiddleManager and Peons
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##### SegmentWriteOutMediumFactory
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#### Indexer
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#### Historical
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### Query
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#### Broker
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#### Router |