mirror of https://github.com/apache/druid.git
112 lines
4.5 KiB
Markdown
112 lines
4.5 KiB
Markdown
---
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id: redis-cache
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title: "Druid Redis Cache"
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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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~ KIND, either express or implied. See the License for the
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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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A cache implementation for Druid based on [Redis](https://github.com/redis/redis).
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Below are guidance and configuration options known to this module.
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## Installation
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Use [pull-deps](../../operations/pull-deps.md) tool shipped with Druid to install this [extension](../../configuration/extensions.md#community-extensions) on broker, historical and middle manager nodes.
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```bash
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java -classpath "druid_dir/lib/*" org.apache.druid.cli.Main tools pull-deps -c org.apache.druid.extensions.contrib:druid-redis-cache:{VERSION}
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```
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## Enabling
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To enable this extension after installation,
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1. [include](../../configuration/extensions.md#loading-extensions) this `druid-redis-cache` extension
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2. to enable cache on broker nodes, follow [broker caching docs](../../configuration/index.md#broker-caching) to set related properties
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3. to enable cache on historical nodes, follow [historical caching docs](../../configuration/index.md#historical-caching) to set related properties
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4. to enable cache on middle manager nodes, follow [peon caching docs](../../configuration/index.md#peon-caching) to set related properties
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5. set `druid.cache.type` to `redis`
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6. add the following properties
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## Configuration
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### Cluster mode
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To utilize a redis cluster, following properties must be set.
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Note: some redis cloud service providers provide redis cluster service via a redis proxy, for these clusters, please follow the [Standalone mode](#standalone-mode) configuration below.
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| Properties |Description|Default|Required|
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|--------------------|-----------|-------|--------|
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|`druid.cache.cluster.nodes`| Redis nodes in a cluster, represented in comma separated string. See example below | None | yes |
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|`druid.cache.cluster.maxRedirection`| Max retry count | 5 | no |
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#### Example
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```properties
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# a typical redis cluster with 6 nodes
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druid.cache.cluster.nodes=127.0.0.1:7001,127.0.0.1:7002,127.0.0.1:7003,127.0.0.1:7004,127.0.0.1:7005,127.0.0.1:7006
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```
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### Standalone mode
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To use a standalone redis, following properties must be set.
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| Properties |Description|Default|Required|
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|--------------------|-----------|-------|--------|
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|`druid.cache.host`|Redis server host|None|yes|
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|`druid.cache.port`|Redis server port|None|yes|
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|`druid.cache.database`|Redis database index|0|no|
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Note: if both `druid.cache.cluster.nodes` and `druid.cache.host` are provided, cluster mode is preferred.
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### Shared Properties
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Except for the properties above, there are some extra properties which can be customized to meet different needs.
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| Properties |Description|Default|Required|
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|--------------------|-----------|-------|--------|
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|`druid.cache.password`| Password to access redis server/cluster | None |no|
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|`druid.cache.expiration`|Expiration for cache entries | P1D |no|
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|`druid.cache.timeout`|Timeout for connecting to Redis and reading entries from Redis|PT2S|no|
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|`druid.cache.maxTotalConnections`|Max total connections to Redis|8|no|
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|`druid.cache.maxIdleConnections`|Max idle connections to Redis|8|no|
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|`druid.cache.minIdleConnections`|Min idle connections to Redis|0|no|
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For `druid.cache.expiration` and `druid.cache.timeout` properties, values can be format of `Period` or a number in milliseconds.
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```properties
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# Period format(recomended)
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# cache expires after 1 hour
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druid.cache.expiration=PT1H
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# or in number(milliseconds) format
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# 1 hour = 3_600_000 milliseconds
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druid.cache.expiration=3600000
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```
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## Metrics
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In addition to the normal cache metrics, the redis cache implementation also reports the following in both `total` and `delta`
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|Metric|Description|Normal value|
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|------|-----------|------------|
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|`query/cache/redis/*/requests`|Count of requests to redis cache|whatever request to redis will increase request count by 1|
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