org.apache.hudi.org.apache.hadoop.hbase.io.hfile.package-info Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Provides implementations of {@link org.apache.hadoop.hbase.io.hfile.HFile} and HFile
* {@link org.apache.hadoop.hbase.io.hfile.BlockCache}. Caches are configured (and instantiated)
* by {@link org.apache.hadoop.hbase.io.hfile.CacheConfig}. See head of the
* {@link org.apache.hadoop.hbase.io.hfile.CacheConfig} class for constants that define
* cache options and configuration keys to use setting cache options. Cache implementations
* include the default, native on-heap {@link org.apache.hadoop.hbase.io.hfile.LruBlockCache} and a
* {@link org.apache.hadoop.hbase.io.hfile.bucket.BucketCache} that has a bunch of deploy formats
* including acting as a L2 for LruBlockCache -- when a block is evicted from LruBlockCache, it
* goes to the BucketCache and when we search a block, we look in both places -- or, the
* most common deploy type,
* using {@link org.apache.hadoop.hbase.io.hfile.CombinedBlockCache}, BucketCache is used as
* a host for data blocks with meta blocks in an instance of LruBlockCache. BucketCache
* can also be onheap, offheap, and file-backed.
*
* Which BlockCache should I use?
* By default LruBlockCache is on. If you would like to cache more, and offheap (offheap
* usually means less GC headache), try enabling * BucketCache. Fetching will always
* be slower when fetching from BucketCache but latencies tend to be less erratic over time
* (roughly because GC is less). See Nick Dimiduk's
* BlockCache 101 for some numbers.
*
* Enabling {@link org.apache.hadoop.hbase.io.hfile.bucket.BucketCache}
* See the HBase Reference Guide Enable BucketCache.
*
*/
package org.apache.hadoop.hbase.io.hfile;