64 lines
1.8 KiB
Plaintext
64 lines
1.8 KiB
Plaintext
[[ignore-above]]
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=== `ignore_above`
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Strings longer than the `ignore_above` setting will not be indexed or stored.
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For arrays of strings, `ignore_above` will be applied for each array element separately and string elements longer than `ignore_above` will not be indexed or stored.
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NOTE: All strings/array elements will still be present in the `_source` field, if the latter is enabled which is the default in Elasticsearch.
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[source,js]
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--------------------------------------------------
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PUT my_index
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{
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"mappings": {
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"_doc": {
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"properties": {
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"message": {
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"type": "keyword",
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"ignore_above": 20 <1>
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}
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}
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}
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}
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}
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PUT my_index/_doc/1 <2>
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{
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"message": "Syntax error"
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}
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PUT my_index/_doc/2 <3>
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{
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"message": "Syntax error with some long stacktrace"
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}
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GET _search <4>
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{
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"aggs": {
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"messages": {
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"terms": {
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"field": "message"
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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<1> This field will ignore any string longer than 20 characters.
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<2> This document is indexed successfully.
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<3> This document will be indexed, but without indexing the `message` field.
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<4> Search returns both documents, but only the first is present in the terms aggregation.
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TIP: The `ignore_above` setting is allowed to have different settings for
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fields of the same name in the same index. Its value can be updated on
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existing fields using the <<indices-put-mapping,PUT mapping API>>.
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This option is also useful for protecting against Lucene's term byte-length
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limit of `32766`.
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NOTE: The value for `ignore_above` is the _character count_, but Lucene counts
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bytes. If you use UTF-8 text with many non-ASCII characters, you may want to
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set the limit to `32766 / 4 = 8191` since UTF-8 characters may occupy at most
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4 bytes.
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