115 lines
4.0 KiB
Plaintext
115 lines
4.0 KiB
Plaintext
[[indices-segments]]
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== Indices Segments
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Provide low level segments information that a Lucene index (shard level)
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is built with. Allows to be used to provide more information on the
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state of a shard and an index, possibly optimization information, data
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"wasted" on deletes, and so on.
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Endpoints include segments for a specific index, several indices, or
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all:
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[source,js]
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--------------------------------------------------
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curl -XGET 'http://localhost:9200/test/_segments'
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curl -XGET 'http://localhost:9200/test1,test2/_segments'
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curl -XGET 'http://localhost:9200/_segments'
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--------------------------------------------------
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Response:
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[source,js]
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--------------------------------------------------
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{
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...
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"_3": {
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"generation": 3,
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"num_docs": 1121,
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"deleted_docs": 53,
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"size_in_bytes": 228288,
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"memory_in_bytes": 3211,
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"committed": true,
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"search": true,
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"version": "4.6",
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"compound": true
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}
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...
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}
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--------------------------------------------------
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_0:: The key of the JSON document is the name of the segment. This name
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is used to generate file names: all files starting with this
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segment name in the directory of the shard belong to this segment.
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generation:: A generation number that is basically incremented when needing to
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write a new segment. The segment name is derived from this
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generation number.
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num_docs:: The number of non-deleted documents that are stored in this segment.
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deleted_docs:: The number of deleted documents that are stored in this segment.
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It is perfectly fine if this number is greater than 0, space is
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going to be reclaimed when this segment gets merged.
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size_in_bytes:: The amount of disk space that this segment uses, in bytes.
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memory_in_bytes:: Segments need to store some data into memory in order to be
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searchable efficiently. This number returns the number of bytes
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that are used for that purpose. A value of -1 indicates that
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Elasticsearch was not able to compute this number.
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committed:: Whether the segment has been sync'ed on disk. Segments that are
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committed would survive a hard reboot. No need to worry in case
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of false, the data from uncommitted segments is also stored in
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the transaction log so that Elasticsearch is able to replay
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changes on the next start.
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search:: Whether the segment is searchable. A value of false would most
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likely mean that the segment has been written to disk but no
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refresh occurred since then to make it searchable.
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version:: The version of Lucene that has been used to write this segment.
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compound:: Whether the segment is stored in a compound file. When true, this
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means that Lucene merged all files from the segment in a single
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one in order to save file descriptors.
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=== Verbose mode
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To add additional information that can be used for debugging, use the `verbose` flag.
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NOTE: The format of additional verbose information is experimental and can change at any time.
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[source,js]
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--------------------------------------------------
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curl -XGET 'http://localhost:9200/test/_segments?verbose=true'
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--------------------------------------------------
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Response:
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[source,js]
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--------------------------------------------------
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{
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...
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"_3": {
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...
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"ram_tree": [
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{
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"description": "postings [PerFieldPostings(format=1)]",
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"size_in_bytes": 2696,
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"children": [
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{
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"description": "format 'Lucene50_0' ...",
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"size_in_bytes": 2608,
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"children" :[ ... ]
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},
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...
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]
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},
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...
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]
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}
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...
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}
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-------------------------------------------------- |