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65 lines
2.0 KiB
Plaintext
65 lines
2.0 KiB
Plaintext
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[[mapping-source-field]]
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=== `_source`
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The `_source` field is an automatically generated field that stores the
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actual JSON that was used as the indexed document. It is not indexed
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(searchable), just stored. When executing "fetch" requests, like
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<<docs-get,get>> or
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<<search-search,search>>, the `_source` field is
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returned by default.
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Though very handy to have around, the source field does incur storage
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overhead within the index. For this reason, it can be disabled. For
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example:
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[source,js]
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--------------------------------------------------
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{
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"tweet" : {
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"_source" : {"enabled" : false}
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}
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}
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--------------------------------------------------
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[float]
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==== Compression
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*From version 0.90 onwards, all stored fields (including `_source`) are
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always compressed.*
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For versions before 0.90:
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The source field can be compressed (LZF) when stored in the index. This
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can greatly reduce the index size, as well as possibly improving
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performance (when decompression overhead is better than loading a bigger
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source from disk). The code takes special care to decompress the source
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only when needed, for example decompressing it directly into the REST
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stream of a result.
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In order to enable compression, the `compress` option should be set to
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`true`. By default it is set to `false`. Note, this can be changed on an
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existing index, as a mix of compressed and uncompressed sources is
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supported.
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Moreover, a `compress_threshold` can be set to control when the source
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will be compressed. It accepts a byte size value (for example `100b`,
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`10kb`). Note, `compress` should be set to `true`.
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[float]
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==== Includes / Excludes
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Allow to specify paths in the source that would be included / excluded
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when it's stored, supporting `*` as wildcard annotation. For example:
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[source,js]
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--------------------------------------------------
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{
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"my_type" : {
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"_source" : {
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"includes" : ["path1.*", "path2.*"],
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"excludes" : ["pat3.*"]
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}
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}
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}
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--------------------------------------------------
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