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Docs for snapshots as simple archives (elastic#86261)
Adds documentation for the new snapshots as archive feature. Relates elastic#81210
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docs/reference/snapshot-restore/cluster-index-compat.asciidoc
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| |==== | ||
| | 4+^h| Cluster version | ||
| h| Index creation version | 6.8 | 7.0–7.1 | 7.2–{prev-major-last} | 8.0–{minor-version} | ||
| | 5.0–5.6 | {yes-icon} | {no-icon} | {no-icon} | {no-icon} | ||
| | 6.0–6.7 | {yes-icon} | {yes-icon} | {yes-icon} | {no-icon} | ||
| | 6.8 | {yes-icon} | {no-icon} | {yes-icon} | {no-icon} | ||
| | 7.0–7.1 | {no-icon} | {yes-icon} | {yes-icon} | {yes-icon} | ||
| | 7.2–{prev-major-last} | {no-icon} | {no-icon} | {yes-icon} | {yes-icon} | ||
| | 8.0–{minor-version} | {no-icon} | {no-icon} | {no-icon} | {yes-icon} | ||
| | 5+^h| Cluster version | ||
| h| Index creation version | 6.8 | 7.0–7.1 | 7.2–{prev-major-last} | 8.0–8.2 | 8.3-{minor-version} | ||
| | 5.0–5.6 | {yes-icon} | {no-icon} | {no-icon} | {no-icon} | {yes-icon}footnote:archive[Using <<archive-indices,archive>> functionality] | ||
| | 6.0–6.7 | {yes-icon} | {yes-icon} | {yes-icon} | {no-icon} | {yes-icon}footnote:archive[] | ||
| | 6.8 | {yes-icon} | {no-icon} | {yes-icon} | {no-icon} | {yes-icon}footnote:archive[] | ||
| | 7.0–7.1 | {no-icon} | {yes-icon} | {yes-icon} | {yes-icon} | {yes-icon} | ||
| | 7.2–{prev-major-last} | {no-icon} | {no-icon} | {yes-icon} | {yes-icon} | {yes-icon} | ||
| | 8.0–8.2 | {no-icon} | {no-icon} | {no-icon} | {yes-icon} | {yes-icon} | ||
| | 8.3–{minor-version} | {no-icon} | {no-icon} | {no-icon} | {yes-icon} | {yes-icon} | ||
| |==== |
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| [[archive-indices]] | ||
| == Reading indices from older {es} versions | ||
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| {es} has full query and write support for indices created in the previous major | ||
| version. If you have indices created in {es} versions 5 or 6, you can now use | ||
| the archive functionality to import them into newer {es} versions as well. | ||
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| The archive functionality provides slower read-only access to older {es} data, | ||
| for compliance or regulatory reasons, the occasional lookback or investigation, | ||
| or to rehydrate parts of it. Access to the data is expected to be infrequent, | ||
| and can therefore happen with limited performance and query capabilities. | ||
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| For this, {es} has the ability to access older snapshot repositories | ||
| (going back to version 5). The legacy indices in the <<snapshot-restore,snapshot repository>> | ||
| can either be <<restore-snapshot-api,restored>>, or can be directly accessed | ||
| via <<searchable-snapshots,searchable snapshots>> so that the archived data | ||
| won't even need to fully reside on local disks for access. | ||
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| [discrete] | ||
| [[archive-indices-supported-field-types]] | ||
| === Supported field types | ||
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| Old mappings are imported as much "as-is" as possible into {es} 8, but only | ||
| provide regular query capabilities on a select subset of fields: | ||
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| - <<number,Numeric types>> | ||
| - <<boolean,`boolean` type>> | ||
| - <<ip,`ip` type>> | ||
| - <<geo-point,`geo_point` type>> | ||
| - <<date,`date` types>>: the date `format` setting on date fields is supported | ||
| as long as it behaves similarly across these versions. In case it is not, | ||
| for example {ref-7x}/migrate-to-java-time.html[when using custom date formats], | ||
| this field can be updated on legacy indices so that it can be changed by a | ||
| user if need be. | ||
| - <<keyword-field-type,`keyword` type>>: the `normalizer` setting on keyword | ||
| fields is supported as long as it behaves similarly across these versions. | ||
| In case it is not, this field can be updated on legacy indices if need be. | ||
| - <<text-field-type,`text` type>>: scoring capabilities are limited, and all | ||
| queries return constant scores that are equal to 1.0. The `analyzer` | ||
| settings on text fields are supported as long as they behave similarly | ||
| across these versions. In case they do not, they can be updated on legacy | ||
| indices if need be. | ||
| - <<multi-fields,Multi-fields>> | ||
| - <<field-alias,Field aliases>> | ||
| - <<object,`object`>> fields | ||
| - some basic metadata fields, e.g. `_type` for querying {es} 5 indices | ||
| - <<runtime-mapping-fields,runtime fields>> | ||
| - <<mapping-source-field,`_source` field>> | ||
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| {es} 5 indices with mappings that have {ref-7x}/removal-of-types.html[multiple mapping types] | ||
| are collapsed together on a best-effort basis before they are imported. | ||
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| In case the auto-import of mappings does not work, or the new {es} version | ||
| can't make sense of the mapping, it falls back to importing the index without | ||
| the mapping, but stores the original mapping in the <<mapping-meta-field,_meta>> | ||
| section of the imported index. The legacy mapping can then be introspected | ||
| using the <<indices-get-mapping,GET mapping>> API and an updated mapping can | ||
| be manually put in place using the <<indices-put-mapping,update mapping>> API, | ||
| copying and adapting relevant sections of the legacy mapping to work with the | ||
| current {es} version. While auto-import is expected to work in most cases, | ||
| failures of doing so should be https://github.com/elastic/elasticsearch/issues/new/choose[raised] | ||
| with the Elastic team for future improvements. | ||
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| [discrete] | ||
| === Supported APIs | ||
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| Archive indices are read-only, and provide data access via the | ||
| <<search-search,search>> and <<search-field-caps,field capabilities>> APIs. | ||
| They do not support the <<docs-get,Get API>> nor any write APIs. | ||
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| Archive indices allow running queries as well as aggregations in so far as | ||
| they are <<archive-indices-supported-field-types,supported by the given field type>>. | ||
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| Due to `_source` access the data can also be <<docs-reindex,reindexed>> | ||
| to a new index that has full compatibility with the current {es} version. | ||
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| [discrete] | ||
| === How to upgrade older {es} 5 or 6 clusters? | ||
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| Take a snapshot of the indices in the old cluster, delete indices that are not | ||
| directly supported by ES 8 (i.e. indices older than 7.0), upgrade the cluster | ||
| without the old indices, and then <<restore-snapshot-api,restore>> the legacy | ||
| indices from the snapshot or <<searchable-snapshots-api-mount-snapshot,mount>> | ||
| them via searchable snapshots. | ||
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| In the future, we plan on streamlining the upgrade process going forward, | ||
| making it easier to take legacy indices along when going to future major | ||
| {es} versions. |