53 lines
1.5 KiB
Plaintext
53 lines
1.5 KiB
Plaintext
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[[mapping-id-field]]
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=== `_id`
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Each document indexed is associated with an id and a type. The `_id`
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field can be used to index just the id, and possible also store it. By
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default it is not indexed and not stored (thus, not created).
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Note, even though the `_id` is not indexed, all the APIs still work
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(since they work with the `_uid` field), as well as fetching by ids
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using `term`, `terms` or `prefix` queries/filters (including the
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specific `ids` query/filter).
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The `_id` field can be enabled to be indexed, and possibly stored,
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using:
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[source,js]
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--------------------------------------------------
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{
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"tweet" : {
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"_id" : {"index": "not_analyzed", "store" : "yes"}
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}
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}
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--------------------------------------------------
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The `_id` mapping can also be associated with a `path` that will be used
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to extract the id from a different location in the source document. For
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example, having the following mapping:
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[source,js]
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--------------------------------------------------
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{
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"tweet" : {
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"_id" : {
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"path" : "post_id"
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}
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}
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}
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--------------------------------------------------
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Will cause `1` to be used as the id for:
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[source,js]
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--------------------------------------------------
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{
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"message" : "You know, for Search",
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"post_id" : "1"
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}
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--------------------------------------------------
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This does require an additional lightweight parsing step while indexing,
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in order to extract the id to decide which shard the index operation
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will be executed on.
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