59 lines
2.8 KiB
Markdown
59 lines
2.8 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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~ 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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~ 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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To use this Apache Druid extension, make sure to [include](../../development/extensions.md#loading-extensions) `druid-redis-cache` extension.
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A cache implementation for Druid based on [Redis](https://github.com/antirez/redis).
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Below are the configuration options known to this module.
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Note that just adding these properties does not enable the cache. You still need to add the `druid.<process-type>.cache.useCache` and `druid.<process-type>.cache.populateCache` properties for the processes you want to enable the cache on as described in the [cache configuration docs](../../configuration/index.html#cache-configuration).
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A possible configuration would be to keep the properties below in your `common.runtime.properties` file (present on all processes) and then add `druid.<nodetype>.cache.useCache` and `druid.<nodetype>.cache.populateCache` in the `runtime.properties` file of the process types you want to enable caching on.
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## Configuration
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|`common.runtime.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.expiration`|Expiration(in milliseconds) for cache entries|24 * 3600 * 1000|no|
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|`druid.cache.timeout`|Timeout(in milliseconds) for get cache entries from Redis|2000|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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## Enabling
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To enable the redis cache, include this module on the loadList and set `druid.cache.type` to `redis` in your properties.
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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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