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Exists Query
editExists Query
editReturns documents that have at least one non-null
value in the original field:
{ "exists" : { "field" : "user" } }
For instance, these documents would all match the above query:
An empty string is a non- |
|
Even though the |
|
At least one non- |
These documents would not match the above query:
This field has no values. |
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At least one non- |
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The |
null_value
mapping
editIf the field mapping includes the null_value
setting
then explicit null
values are replaced with the specified null_value
. For
instance, if the user
field were mapped as follows:
"user": { "type": "string", "null_value": "_null_" }
then explicit null
values would be indexed as the string _null_
, and the
following docs would match the exists
filter:
{ "user": null } { "user": [null] }
However, these docs—without explicit null
values—would still have
no values in the user
field and thus would not match the exists
filter:
{ "user": [] } { "foo": "bar" }
missing
query
editThe exists query can advantageously replace the missing
query when used inside a must_not clause as follows:
"bool": { "must_not": { "exists": { "field": "user" } } }
This query returns documents that have no value in the user field.