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Index settings
Index settings can be of two types: cluster-level settings that affect all indexes in the cluster and index-level settings that affect individual indexes.
To learn more about static and dynamic settings, see Configuring OpenSearch.
Cluster-level index settings
OpenSearch supports the following cluster-level index settings. All settings in this list are dynamic:
-
action.auto_create_index
(Boolean): Automatically creates an index if the index doesn’t already exist. Also applies any index templates that are configured. Default istrue
. -
action.destructive_requires_name
(Boolean): When set totrue
, you must specify the index name to delete an index. You cannot delete all indexes or use wildcards. Default istrue
. -
cluster.default.index.refresh_interval
(Time unit): Sets the refresh interval when theindex.refresh_interval
setting is not provided. This setting can be useful when you want to set a default refresh interval across all indexes in a cluster and support thesearchIdle
setting. You cannot set the interval lower than thecluster.minimum.index.refresh_interval
setting. -
cluster.minimum.index.refresh_interval
(Time unit): Sets the minimum refresh interval and applies it to all indexes in the cluster. Thecluster.default.index.refresh_interval
setting should be higher than this setting’s value. If, during index creation, theindex.refresh_interval
setting is lower than the minimum set, index creation fails. -
cluster.indices.close.enable
(Boolean): Enables closing of open indexes in OpenSearch. Default istrue
. -
indices.recovery.max_bytes_per_sec
(String): Limits the total inbound and outbound recovery traffic for each node. This applies to peer recoveries and snapshot recoveries. Default is40mb
. If you set the recovery traffic value to less than or equal to0mb
, rate limiting will be disabled, which causes recovery data to be transferred at the highest possible rate. -
indices.recovery.max_concurrent_file_chunks
(Integer): The number of file chunks sent in parallel for each recovery operation. Default is2
. -
indices.recovery.max_concurrent_operations
(Integer): The number of operations sent in parallel for each recovery. Default is1
. -
indices.recovery.max_concurrent_remote_store_streams
(Integer): The number of streams to the remote repository that can be opened in parallel when recovering a remote store index. Default is20
. -
indices.fielddata.cache.size
(String): The maximum size of the field data cache. May be specified as an absolute value (for example,8GB
) or a percentage of the node heap (for example,50%
). This value is static so you must specify it in theopensearch.yml
file. If you don’t specify this setting, the maximum size is unlimited. This value should be smaller than theindices.breaker.fielddata.limit
. For more information, see Field data circuit breaker.
Index-level index settings
You can specify index settings at index creation. There are two types of index settings:
- Static index-level index settings are settings that you cannot update while the index is open. To update a static setting, you must close the index, update the setting, and then reopen the index.
- Dynamic index-level index settings are settings that you can update at any time.
Specifying a setting when creating an index
When creating an index, you can specify its static or dynamic settings as follows:
PUT /testindex
{
"settings": {
"index.number_of_shards": 1,
"index.number_of_replicas": 2
}
}
Static index-level index settings
OpenSearch supports the following static index-level index settings:
-
index.number_of_shards
(Integer): The number of primary shards in the index. Default is 1. -
index.number_of_routing_shards
(Integer): The number of routing shards used to split an index. -
index.shard.check_on_startup
(Boolean): Whether the index’s shards should be checked for corruption. Available options arefalse
(do not check for corruption),checksum
(check for physical corruption), andtrue
(check for both physical and logical corruption). Default isfalse
. -
index.codec
(String): Determines how the index’s stored fields are compressed and stored on disk. This setting impacts the size of the index shards and the performance of the index operations.Valid values are:
default
best_compression
zstd
(OpenSearch 2.9 and later)zstd_no_dict
(OpenSearch 2.9 and later)
For
zstd
andzstd_no_dict
, you can specify the compression level in theindex.codec.compression_level
setting. For more information, see Index codec settings. Optional. Default isdefault
. -
index.codec.compression_level
(Integer): The compression level setting provides a tradeoff between compression ratio and speed. A higher compression level results in a higher compression ratio (smaller storage size) with a tradeoff in speed (slower compression and decompression speeds lead to greater indexing and search latencies). Can only be specified ifindex.codec
is set tozstd
andzstd_no_dict
compression levels in OpenSearch 2.9 and later. Valid values are integers in the [1, 6] range. For more information, see Index codec settings. Optional. Default is 3. -
index.routing_partition_size
(Integer): The number of shards a custom routing value can go to. Routing helps an imbalanced cluster by relocating values to a subset of shards rather than a single shard. To enable routing, set this value to greater than 1 but less thanindex.number_of_shards
. Default is 1. -
index.soft_deletes.retention_lease.period
(Time unit): The maximum amount of time to retain a shard’s history of operations. Default is12h
. -
index.load_fixed_bitset_filters_eagerly
(Boolean): Whether OpenSearch should preload cached filters. Available options aretrue
andfalse
. Default istrue
. -
index.hidden
(Boolean): Whether the index should be hidden. Hidden indexes are not returned as part of queries that have wildcards. Available options aretrue
andfalse
. Default isfalse
. -
index.merge.policy
(String): This setting controls the merge policy for the Lucene segments. The available options aretiered
andlog_byte_size
. The default istiered
, but for time-series data, such as log events, we recommend that you use thelog_byte_size
merge policy, which can improve query performance when conducting range queries on the@timestamp
field. We recommend that you not change the merge policy of an existing index. Instead, configure this setting when creating a new index. -
index.merge_on_flush.enabled
(Boolean): This setting controls Apache Lucene’s merge-on-refresh feature that aims to reduce the number of segments by performing merges on refresh (or in terms of OpenSearch, on flush). Default istrue
. -
index.merge_on_flush.max_full_flush_merge_wait_time
(Time unit): This setting sets the amount of time to wait for merges whenindex.merge_on_flush.enabled
is enabled. Default is10s
. -
index.merge_on_flush.policy
(defaultmerge-on-flush): This setting controls which merge policy should be used when index.merge_on_flush.enabled
is enabled. Default isdefault
. index.check_pending_flush.enabled
(Boolean): This setting controls the Apache LucenecheckPendingFlushOnUpdate
index writer setting, which specifies whether an indexing thread should check for pending flushes on an update in order to flush indexing buffers to disk. Default istrue
.
Updating a static index setting
You can update a static index setting only on a closed index. The following example demonstrates updating the index codec setting.
First, close an index:
POST /testindex/_close
Then update the settings by sending a request to the _settings
endpoint:
PUT /testindex/_settings
{
"index": {
"codec": "zstd_no_dict",
"codec.compression_level": 3
}
}
Last, reopen the index to enable read and write operations:
POST /testindex/_open
For more information about updating settings, including supported query parameters, see Update settings.
Dynamic index-level index settings
OpenSearch supports the following dynamic index-level index settings:
-
index.number_of_replicas
(Integer): The number of replica shards each primary shard should have. For example, if you have 4 primary shards and setindex.number_of_replicas
to 3, the index has 12 replica shards. Default is 1. -
index.auto_expand_replicas
(String): Whether the cluster should automatically add replica shards based on the number of data nodes. Specify a lower bound and upper limit (for example, 0–9) orall
for the upper limit. For example, if you have 5 data nodes and setindex.auto_expand_replicas
to 0–3, then the cluster does not automatically add another replica shard. However, if you set this value to0-all
and add 2 more nodes for a total of 7, the cluster will expand to now have 6 replica shards. Default is disabled. -
index.search.idle.after
(Time unit): The amount of time a shard should wait for a search or get request until it goes idle. Default is30s
. -
index.search.default_pipeline
(String): The name of the search pipeline that is used if no pipeline is explicitly set when searching an index. If a default pipeline is set and the pipeline doesn’t exist, then the index requests fail. Use the pipeline name_none
to specify no default search pipeline. For more information, see Default search pipeline. -
index.refresh_interval
(Time unit): How often the index should refresh, which publishes its most recent changes and makes them available for searching. Can be set to-1
to disable refreshing. Default is1s
. -
index.max_result_window
(Integer): The maximum value offrom
+size
for searches of the index.from
is the starting index to search from, andsize
is the number of results to return. Default is 10000. -
index.max_inner_result_window
(Integer): The maximum value offrom
+size
that specifies the number of returned nested search hits and most relevant document aggregated during the query.from
is the starting index to search from, andsize
is the number of top hits to return. Default is 100. -
index.max_rescore_window
(Integer): The maximum value ofwindow_size
for rescore requests to the index. Rescore requests reorder the index’s documents and return a new score, which can be more precise. Default is the same asindex.max_inner_result_window
or 10000 by default. -
index.max_docvalue_fields_search
(Integer): The maximum number ofdocvalue_fields
allowed in a query. Default is 100. -
index.max_script_fields
(Integer): The maximum number ofscript_fields
allowed in a query. Default is 32. -
index.max_ngram_diff
(Integer): The maximum difference betweenmin_gram
andmax_gram
values for theNGramTokenizer
andNGramTokenFilter
. Default is 1. -
index.max_shingle_diff
(Integer): The maximum difference betweenmax_shingle_size
andmin_shingle_size
to feed into theshingle
token filter. Default is 3. -
index.max_refresh_listeners
(Integer): The maximum number of refresh listeners each shard is allowed to have. -
index.analyze.max_token_count
(Integer): The maximum number of tokens that can be returned from the_analyze
API operation. Default is 10000. -
index.highlight.max_analyzed_offset
(Integer): The number of characters a highlight request can analyze. Default is 1000000. -
index.max_terms_count
(Integer): The maximum number of terms a terms query can accept. Default is 65536. -
index.max_regex_length
(Integer): The maximum character length of regex that can be in a regexp query. Default is 1000. -
index.query.default_field
(List): A field or list of fields that OpenSearch uses in queries in case a field isn’t specified in the parameters. -
index.query.max_nested_depth
(Integer): The maximum number of nesting levels fornested
queries. Default isInteger.MAX_VALUE
. Minimum is 1 (singlenested
query). -
index.routing.allocation.enable
(String): Specifies options for the index’s shard allocation. Available options areall
(allow allocation for all shards),primaries
(allow allocation only for primary shards),new_primaries
(allow allocation only for new primary shards), andnone
(do not allow allocation). Default isall
. -
index.routing.rebalance.enable
(String): Enables shard rebalancing for the index. Available options areall
(allow rebalancing for all shards),primaries
(allow rebalancing only for primary shards),replicas
(allow rebalancing only for replicas), andnone
(do not allow rebalancing). Default isall
. -
index.gc_deletes
(Time unit): The amount of time to retain a deleted document’s version number. Default is60s
. -
index.default_pipeline
(String): The default ingest node pipeline for the index. If the default pipeline is set and the pipeline does not exist, then index requests fail. The pipeline name_none
specifies that the index does not have an ingest pipeline. -
index.final_pipeline
(String): The final ingest node pipeline for the index. If the final pipeline is set and the pipeline does not exist, then index requests fail. The pipeline name_none
specifies that the index does not have an ingest pipeline. -
index.optimize_doc_id_lookup.fuzzy_set.enabled
(Boolean): This setting controls whetherfuzzy_set
should be enabled in order to optimize document ID lookups in index or search calls by using an additional data structure, in this case, the Bloom filter data structure. Enabling this setting improves performance for upsert and search operations that rely on document IDs by creating a new data structure (Bloom filter). The Bloom filter allows for the handling of negative cases (that is, IDs being absent in the existing index) through faster off-heap lookups. Note that creating a Bloom filter requires additional heap usage during indexing time. Default isfalse
. -
index.optimize_doc_id_lookup.fuzzy_set.false_positive_probability
(Double): Sets the false-positive probability for the underlyingfuzzy_set
(that is, the Bloom filter). A lower false-positive probability ensures higher throughput for upsert and get operations but results in increased storage and memory use. Allowed values range between0.01
and0.50
. Default is0.20
.
Updating a dynamic index setting
You can update a dynamic index setting at any time through the API. For example, to update the refresh interval, use the following request:
PUT /testindex/_settings
{
"index": {
"refresh_interval": "2s"
}
}
For more information about updating settings, including supported query parameters, see Update settings.