54 lines
1.3 KiB
Plaintext
54 lines
1.3 KiB
Plaintext
[[null-value]]
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=== `null_value`
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A `null` value cannot be indexed or searched. When a field is set to `null`,
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(or an empty array or an array of `null` values) it is treated as though that
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field has no values.
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The `null_value` parameter allows you to replace explicit `null` values with
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the specified value so that it can be indexed and searched. For instance:
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[source,console]
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--------------------------------------------------
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PUT my-index-000001
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{
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"mappings": {
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"properties": {
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"status_code": {
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"type": "keyword",
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"null_value": "NULL" <1>
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}
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}
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}
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}
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PUT my-index-000001/_doc/1
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{
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"status_code": null
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}
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PUT my-index-000001/_doc/2
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{
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"status_code": [] <2>
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}
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GET my-index-000001/_search
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{
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"query": {
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"term": {
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"status_code": "NULL" <3>
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}
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}
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}
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--------------------------------------------------
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<1> Replace explicit `null` values with the term `NULL`.
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<2> An empty array does not contain an explicit `null`, and so won't be replaced with the `null_value`.
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<3> A query for `NULL` returns document 1, but not document 2.
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IMPORTANT: The `null_value` needs to be the same data type as the field. For
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instance, a `long` field cannot have a string `null_value`.
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NOTE: The `null_value` only influences how data is indexed, it doesn't modify
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the `_source` document.
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