93 lines
3.6 KiB
Plaintext
93 lines
3.6 KiB
Plaintext
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[[reindex-upgrade]]
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=== Reindex to upgrade
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Elasticsearch is able to use indices created in the previous major version
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only. For instance, Elasticsearch 6.x can use indices created in
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Elasticsearch 5.x, but not those created in Elasticsearch 2.x or before.
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NOTE: Elasticsearch 6.x nodes will fail to start in the presence of too old indices.
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If you are running an Elasticsearch 5.x cluster which contains indices that
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were created before 5.x, you will either need to delete those old indices or
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to reindex them before upgrading to 6.x. See <<reindex-upgrade-inplace>>.
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If you are running an Elasticsearch 2.x cluster or older, you have two options:
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* First upgrade to Elasticsearch 5.x, reindex the old indices, then upgrade
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to 6.x. See <<reindex-upgrade-inplace>>.
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* Create a new 6.x cluster and use reindex-from-remote to import indices
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directly from the 2.x cluster. See <<reindex-upgrade-remote>>.
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[[reindex-upgrade-inplace]]
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==== Reindex in place
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If you are running a 5.x cluster which contains indices created in
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Elasticsearch 2.x, you will need to reindex (or delete) those indices before
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upgrading to Elasticsearch 6.x.
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The reindex process works as follows:
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* Create a new index, copying the mappings and settings from the old index.
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Set the `refresh_interval` to `-1` and the `number_of_replicas` to `0` for
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efficient reindexing.
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* Reindex all documents from the old index to the new index using the
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<<docs-reindex,reindex API>>.
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* Reset the `refresh_interval` and `number_of_replicas` to the values
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used in the old index, and wait for the index to become green.
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* In a single <<indices-aliases,update aliases>> request:
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* Delete the old index.
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* Add an alias with the old index name to the new index.
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* Add any aliases that existed on the old index to the new index.
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At the end of this process, you will have a new 5.x index which can be used
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by an Elasticsearch 6.x cluster.
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[[reindex-upgrade-remote]]
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==== Upgrading with reindex-from-remote
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If you are running a 1.x or 2.x cluster and would like to migrate directly to 6.x
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without first migrating to 5.x, you can do so using
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<<reindex-from-remote,reindex-from-remote>>.
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[WARNING]
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=============================================
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Elasticsearch includes backwards compatibility code that allows indices from
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the previous major version to be upgraded to the current major version. By
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moving directly from Elasticsearch 2.x or before to 6.x, you will have to solve any
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backwards compatibility issues yourself.
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=============================================
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You will need to set up a 6.x cluster alongside your existing old cluster.
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The 6.x cluster needs to have access to the REST API of the old cluster.
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For each old index that you want to transfer to the 6.x cluster, you will need
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to:
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* Create a new index in 6.x with the appropriate mappings and settings. Set
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the `refresh_interval` to `-1` and set `number_of_replicas` to `0` for
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faster reindexing.
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* Use <<reindex-from-remote,reindex-from-remote>> to pull documents from the
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old index into the new 6.x index.
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* If you run the reindex job in the background (with `wait_for_completion` set
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to `false`), the reindex request will return a `task_id` which can be used to
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monitor progress of the reindex job in the <<tasks,task API>>:
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`GET _tasks/TASK_ID`.
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* Once reindex has completed, set the `refresh_interval` and
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`number_of_replicas` to the desired values (the defaults are `30s` and `1`
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respectively).
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* Once the new index has finished replication, you can delete the old index.
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The 6.x cluster can start out small, and you can gradually move nodes from the
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old cluster to the 6.x cluster as you migrate indices across.
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