65 lines
3.1 KiB
Plaintext
65 lines
3.1 KiB
Plaintext
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[[indices-shrink-index]]
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== Shrink Index
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The shrink index API allows to shrink an existing index into a new index with a single shard.
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In order to shrink an index, all its shards must be allocated on a single node in the cluster.
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This is required since the shrink command will copy all shards index files into the target index
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data folder when the primary of the target index is initially allocated.
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When an index is shrunk no write operations should happen to the source index. Elasticsearch will
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enforce the `read-only` property when the shrink command is executed. All operations necessary to shrink the
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source index are executed during initial primary recovery. Once the target index primary shard is started the
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shrink operation has successfully finished. To monitor status and progress use <<cat-recovery>>
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To shrink and index all shards of that index must be allocated on a single node.
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[source,js]
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--------------------------------------------------
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$ curl -XPUT 'http://localhost:9200/logs/_settings' -d '{
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"settings" : {
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"index.routing.allocation.require._name" : "shrink_node_name", <1>
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"index.blocks.write" : true <2>
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}
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}'
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--------------------------------------------------
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<1> Forces the relocation of all of the indices shards to the node `shrink_node_name`
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<2> Prevents write operations to this index while still allowing metadata changes like deleting the index.
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The above second curl example shows how an index called `logs` can be
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forced to allocate at least one copy of each shard on a specific node in the cluster.
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The `_shrink` API is similar to <<indices-create-index>> and accepts `settings` and `aliases` for the target index.
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[source,js]
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--------------------------------------------------
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$ curl -XPUT 'http://localhost:9200/logs/_shrink/logs_single_shard' -d '{
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"settings" : {
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"index.codec" : "best_compression", <1>
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}
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}'
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--------------------------------------------------
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<1> Enables `best_compression` codec on the target index
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The API call above returns immediately once the target index is created but doesn't wait
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for the shrink operation to start. Once the target indices primary shard moves to state `initializing`
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the shrink operation has started.
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[float]
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[[shrink-index-limitations]]
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=== Limitations
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Indices can only be shrunk into a single shard if they fully the following requirements:
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* an instance of all of the indices shards must be allocated on a single node
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* the index must not contain more than `2.14 billion` documents (`2147483519`) in total (sum of all shards)
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This is the maximum shard size elasticsearch can support.
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* the index must have more than one shard
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* the index must be `read-only`, ie. have a cluster block set `index.blocks.write=true`
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* the target index must not exist
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* all `index.analysis.*` and `index.similarity.*` settings passed to the `_shrink` call will be overwritten with the
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source indices settings.
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* if the target index can't be allocated on the shrink node, due to throttling or other allocation deciders,
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its primary shard will stay `unassigned` until it can be allocated on that node
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