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* [docs] Migrate docs from AsciiDoc to Markdown (#123507) * delete asciidoc files * add migrated files * fix errors * Disable docs tests * Clarify release notes page titles * Revert "Clarify release notes page titles" This reverts commit8be688648d. * Comment out edternal URI images * Clean up query languages landing pages, link to conceptual docs * Add .md to url * Fixes inference processor nesting. --------- Co-authored-by: Liam Thompson <32779855+leemthompo@users.noreply.github.com> Co-authored-by: Liam Thompson <leemthompo@gmail.com> Co-authored-by: Martijn Laarman <Mpdreamz@gmail.com> Co-authored-by: István Zoltán Szabó <szabosteve@gmail.com> (cherry picked from commitb7e3a1e14b) # Conflicts: # docs/build.gradle # docs/reference/migration/index.asciidoc # docs/reference/migration/migrate_9_0.asciidoc # docs/reference/release-notes.asciidoc # docs/reference/release-notes/9.0.0.asciidoc # docs/reference/release-notes/highlights.asciidoc * Fix build file * Really fix build file --------- Co-authored-by: Colleen McGinnis <colleen.j.mcginnis@gmail.com>
58 lines
1.5 KiB
Markdown
58 lines
1.5 KiB
Markdown
---
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mapped_pages:
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- https://www.elastic.co/guide/en/elasticsearch/plugins/current/mapper-murmur3-usage.html
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---
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# Using the murmur3 field [mapper-murmur3-usage]
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The `murmur3` is typically used within a multi-field, so that both the original value and its hash are stored in the index:
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```console
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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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"my_field": {
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"type": "keyword",
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"fields": {
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"hash": {
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"type": "murmur3"
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}
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}
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}
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}
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}
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}
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```
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Such a mapping would allow to refer to `my_field.hash` in order to get hashes of the values of the `my_field` field. This is only useful in order to run `cardinality` aggregations:
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```console
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# Example documents
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PUT my-index-000001/_doc/1
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{
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"my_field": "This is a document"
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}
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PUT my-index-000001/_doc/2
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{
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"my_field": "This is another document"
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}
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GET my-index-000001/_search
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{
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"aggs": {
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"my_field_cardinality": {
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"cardinality": {
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"field": "my_field.hash" <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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1. Counting unique values on the `my_field.hash` field
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Running a `cardinality` aggregation on the `my_field` field directly would yield the same result, however using `my_field.hash` instead might result in a speed-up if the field has a high-cardinality. On the other hand, it is discouraged to use the `murmur3` field on numeric fields and string fields that are not almost unique as the use of a `murmur3` field is unlikely to bring significant speed-ups, while increasing the amount of disk space required to store the index.
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