Shrinks an existing index into a new index with fewer primary shards.
To make shard allocation easier, we recommend you also remove the index’s replica shards. You can later re-add replica shards as part of the shrink operation.
You can use the following update index settings API request to remove an index’s replica shards, relocates the index’s remaining shards to the same node, and make the index read-only.
Removes replica shards for the index.
Relocates the index’s shards to the
Prevents write operations to this index. Metadata changes, such as deleting the index, are still allowed.
It can take a while to relocate the source index. Progress can be tracked
_cat recovery API, or the
cluster health API can be used to wait until all shards have relocated
The shrink index API allows you to shrink an existing index into a new index
with fewer primary shards. The requested number of primary shards in the target index
must be a factor of the number of shards in the source index. For example an index with
8 primary shards can be shrunk into
1 primary shards or an index
15 primary shards can be shrunk into
1. If the number
of shards in the index is a prime number it can only be shrunk into a single
primary shard. Before shrinking, a (primary or replica) copy of every shard
in the index must be present on the same node.
The current write index on a data stream cannot be shrunk. In order to shrink the current write index, the data stream must first be rolled over so that a new write index is created and then the previous write index can be shrunk.
A shrink operation:
- Creates a new target index with the same definition as the source index, but with a smaller number of primary shards.
- Hard-links segments from the source index into the target index. (If the file system doesn’t support hard-linking, then all segments are copied into the new index, which is a much more time consuming process. Also if using multiple data paths, shards on different data paths require a full copy of segment files if they are not on the same disk since hardlinks don’t work across disks)
- Recovers the target index as though it were a closed index which had just been re-opened.
my_source_index into a new index called
the following request:
Clear the allocation requirement copied from the source index.
Clear the index write block copied from the source index.
The above request returns immediately once the target index has been added to the cluster state — it doesn’t wait for the shrink operation to start.
Indices can only be shrunk if they satisfy the following requirements:
- The target index must not exist.
- The source index must have more primary shards than the target index.
- The number of primary shards in the target index must be a factor of the number of primary shards in the source index. The source index must have more primary shards than the target index.
The index must not contain more than
2,147,483,519documents in total across all shards that will be shrunk into a single shard on the target index as this is the maximum number of docs that can fit into a single shard.
- The node handling the shrink process must have sufficient free disk space to accommodate a second copy of the existing index.
_shrink API is similar to the
create index API
aliases parameters for the target index:
The number of shards in the target index. This must be a factor of the number of shards in the source index.
Best compression will only take affect when new writes are made to the index, such as when force-merging the shard to a single segment.
Mappings may not be specified in the
The shrink process can be monitored with the
API, or the
cluster health API can be used to wait
until all primary shards have been allocated by setting the
_shrink API returns as soon as the target index has been added to the
cluster state, before any shards have been allocated. At this point, all
shards are in the state
unassigned. If, for any reason, the target index
can’t be allocated on the shrink node, its primary shard will remain
unassigned until it can be allocated on that node.
Once the primary shard is allocated, it moves to state
initializing, and the
shrink process begins. When the shrink operation completes, the shard will
active. At that point, Elasticsearch will try to allocate any
replicas and may decide to relocate the primary shard to another node.
- (Required, string) Name of the source index to shrink.
(Required, string) Name of the target index to create.
Index names must meet the following criteria:
- Lowercase only
|, ` ` (space character),
Indices prior to 7.0 could contain a colon (
:), but that’s been deprecated and won’t be supported in 7.0+
Cannot start with
- Cannot be longer than 255 bytes (note it is bytes, so multi-byte characters will count towards the 255 limit faster)
Names starting with
.are deprecated, except for hidden indices and internal indices managed by plugins
(Optional, string) The number of shard copies that must be active before proceeding with the operation. Set to
allor any positive integer up to the total number of shards in the index (
number_of_replicas+1). Default: 1, the primary shard.
See Active shards.
(Optional, time units)
Period to wait for a connection to the master node. If no response is received
before the timeout expires, the request fails and returns an error. Defaults to
(Optional, time units)
Period to wait for a response. If no response is received before the timeout
expires, the request fails and returns an error. Defaults to
- (Optional, alias object) Index aliases which include the target index. Index alias names support date math.
- (Optional, index setting object) Configuration options for the target index. See Index Settings.
(Optional, byte units)
The max primary shard size for the target index. Used to find the optimum number of shards for the target index.
When this parameter is set, each shard’s storage in the target index will not be greater than the parameter.
The shards count of the target index will still be a factor of the source index’s shards count, but if the parameter
is less than the single shard size in the source index, the shards count for the target index will be equal to the source index’s shards count.
For example, when this parameter is set to 50gb, if the source index has 60 primary shards with totaling 100gb, then the
target index will have 2 primary shards, with each shard size of 50gb; if the source index has 60 primary shards
with totaling 1000gb, then the target index will have 20 primary shards; if the source index has 60 primary shards
with totaling 4000gb, then the target index will still have 60 primary shards. This parameter conflicts
settings, only one of them may be set.