73 lines
2.4 KiB
Plaintext
73 lines
2.4 KiB
Plaintext
[[index-modules-store]]
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== Store
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The store module allows you to control how index data is stored and accessed on disk.
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[float]
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[[file-system]]
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=== File system storage types
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There are different file system implementations or _storage types_. The best
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one for the operating environment will be automatically chosen: `mmapfs` on
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Windows 64bit, `simplefs` on Windows 32bit, and `default` (hybrid `niofs` and
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`mmapfs`) for the rest.
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This can be overridden for all indices by adding this to the
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`config/elasticsearch.yml` file:
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[source,yaml]
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---------------------------------
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index.store.type: niofs
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---------------------------------
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It is a _static_ setting that can be set on a per-index basis at index
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creation time:
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[source,json]
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---------------------------------
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PUT /my_index
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{
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"settings": {
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"index.store.type": "niofs"
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}
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}
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---------------------------------
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experimental[This is an expert-only setting and may be removed in the future]
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The following sections lists all the different storage types supported.
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[[simplefs]]`simplefs`::
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The Simple FS type is a straightforward implementation of file system
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storage (maps to Lucene `SimpleFsDirectory`) using a random access file.
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This implementation has poor concurrent performance (multiple threads
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will bottleneck). It is usually better to use the `niofs` when you need
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index persistence.
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[[niofs]]`niofs`::
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The NIO FS type stores the shard index on the file system (maps to
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Lucene `NIOFSDirectory`) using NIO. It allows multiple threads to read
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from the same file concurrently. It is not recommended on Windows
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because of a bug in the SUN Java implementation.
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[[mmapfs]]`mmapfs`::
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The MMap FS type stores the shard index on the file system (maps to
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Lucene `MMapDirectory`) by mapping a file into memory (mmap). Memory
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mapping uses up a portion of the virtual memory address space in your
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process equal to the size of the file being mapped. Before using this
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class, be sure you have allowed plenty of
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<<vm-max-map-count,virtual address space>>.
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[[default_fs]]`default_fs`::
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The `default` type is a hybrid of NIO FS and MMapFS, which chooses the best
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file system for each type of file. Currently only the Lucene term dictionary
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and doc values files are memory mapped to reduce the impact on the operating
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system. All other files are opened using Lucene `NIOFSDirectory`. Address
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space settings (<<vm-max-map-count>>) might also apply if your term
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dictionaries are large.
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