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> Support for Elasticsearch 6.8 was [deprecated](https://gitlab.com/gitlab-org/gitlab/-/issues/350275) in GitLab 14.8 and is scheduled for removal in GitLab 15.0.
When we change Elasticsearch supported versions in GitLab, we announce them in [deprecation notes](https://about.gitlab.com/handbook/marketing/blog/release-posts/#deprecations) in monthly release posts
Memory, CPU, and storage resource amounts vary depending on the amount of data you index into the Elasticsearch cluster. Heavily used Elasticsearch clusters may require more resources. According to
- [CPU](https://www.elastic.co/guide/en/elasticsearch/guide/current/hardware.html#_cpus): Modern processor with multiple cores. GitLab.com has minimal CPU requirements for Elasticsearch. Multiple cores provide extra concurrency, which is more beneficial than faster CPUs.
- [Storage](https://www.elastic.co/guide/en/elasticsearch/guide/current/hardware.html#_disks): Use SSD storage. The total storage size of all Elasticsearch nodes is about 50% of the total size of your Git repositories. It includes one primary and one replica. The [`estimate_cluster_size`](#gitlab-advanced-search-rake-tasks) Rake task ([introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/221177) in GitLab 13.10) uses total repository size to estimate the Advanced Search storage requirements.
source. You must [install it separately](https://www.elastic.co/guide/en/elasticsearch/reference/7.x/install-elasticsearch.html "Elasticsearch 7.x installation documentation") and ensure you select your version. Detailed information on how to install Elasticsearch is out of the scope of this page.
You can install Elasticsearch yourself, or use a cloud hosted offering such as [Elasticsearch Service](https://www.elastic.co/elasticsearch/service) (available on AWS, GCP, or Azure) or the [Amazon OpenSearch](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/gsg.html)
If using the Amazon OpenSearch service, ensure that you select `Elasticsearch 7.10` when configuring Deployment type. As noted in [Versions not supported](#versions-not-supported), Amazon's non-Elasticsearch versions are not yet supported.
You should install Elasticsearch on a separate server. Running Elasticsearch on the same server as GitLab is not recommended and can cause a degradation in GitLab instance performance.
For a single node Elasticsearch cluster, the functional cluster health status is always yellow due to the allocation of the primary shard. Elasticsearch cannot assign replica shards to the same node as primary shards.
Elasticsearch reads and uses indices created in the previous major version. You are not required to change the GitLab configuration when you upgrade Elasticsearch.
If your current index was created before GitLab 13.0, you must reindex from scratch to create an alias to use features such as [zero downtime reindexing](#zero-downtime-reindexing). After you reindex, you can perform zero downtime reindexing and also benefit from future features that use the alias.
To check if your current index was created before GitLab 13.0, use the [Elasticsearch cat aliases API](https://www.elastic.co/guide/en/elasticsearch/reference/7.11/cat-alias.html).
If the returned list of aliases does not contain a `gitlab-production` alias, you must reindex to use features such as zero downtime reindexing.
If the returned list of aliases contains an entry for `gitlab-production` that points to an index
- If you are using GitLab Development Kit, see [GDK Elasticsearch how-to](https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/main/doc/howto/elasticsearch.md).
For GitLab instances with more than 50GB repository data you can follow the instructions for [how to index large instances efficiently](#how-to-index-large-instances-efficiently) below.
| `Elasticsearch indexing` | Enables or disables Elasticsearch indexing and creates an empty index if one does not already exist. You may want to enable indexing but disable search to give the index time to be fully completed, for example. Also, keep in mind that this option doesn't have any impact on existing data, this only enables/disables the background indexer which tracks data changes and ensures new data is indexed. |
| `Pause Elasticsearch indexing` | Enables or disables temporary indexing pause. This is useful for cluster migration/reindexing. All changes are still tracked, but they are not committed to the Elasticsearch index until resumed. |
| `URL` | The URL of your Elasticsearch instance. Use a comma-separated list to support clustering (for example, `http://host1, https://host2:9200`). If your Elasticsearch instance is password-protected, use the `Username` and `Password` fields described below. Alternatively, use inline credentials such as `http://<username>:<password>@<elastic_host>:9200/`. |
| `Username` | The `username` of your Elasticsearch instance. |
| `Password` | The password of your Elasticsearch instance. |
| `Number of Elasticsearch shards` | Elasticsearch indexes are split into multiple shards for performance reasons. In general, you should use at least 5 shards, and indexes with tens of millions of documents need to have more shards ([see below](#guidance-on-choosing-optimal-cluster-configuration)). Changes to this value do not take effect until the index is recreated. You can read more about tradeoffs in the [Elasticsearch documentation](https://www.elastic.co/guide/en/elasticsearch/reference/current/scalability.html). |
| `Number of Elasticsearch replicas` | Each Elasticsearch shard can have a number of replicas. These are a complete copy of the shard, and can provide increased query performance or resilience against hardware failure. Increasing this value increases total disk space required by the index. |
| `Limit namespaces and projects that can be indexed` | Enabling this allows you to select namespaces and projects to index. All other namespaces and projects use database search instead. If you enable this option but do not select any namespaces or projects, none are indexed. [Read more below](#limit-namespaces-and-projects).
| `Using AWS hosted Elasticsearch with IAM credentials` | Sign your Elasticsearch requests using [AWS IAM authorization](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_access-keys.html), [AWS EC2 Instance Profile Credentials](https://docs.aws.amazon.com/codedeploy/latest/userguide/getting-started-create-iam-instance-profile.html#getting-started-create-iam-instance-profile-cli), or [AWS ECS Tasks Credentials](https://docs.aws.amazon.com/AmazonECS/latest/userguide/task-iam-roles.html). Please refer to [Identity and Access Management in Amazon OpenSearch Service](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/ac.html) for details of AWS hosted OpenSearch domain access policy configuration. |
| `AWS Region` | The AWS region in which your OpenSearch Service is located. |
| `Maximum bulk request size (MiB)` | The Maximum Bulk Request size is used by the GitLab Golang-based indexer processes and indicates how much data it ought to collect (and store in memory) in a given indexing process before submitting the payload to Elasticsearch's Bulk API. This setting should be used with the Bulk request concurrency setting (see below) and needs to accommodate the resource constraints of both the Elasticsearch hosts and the hosts running the GitLab Golang-based indexer either from the `gitlab-rake` command or the Sidekiq tasks. |
| `Bulk request concurrency` | The Bulk request concurrency indicates how many of the GitLab Golang-based indexer processes (or threads) can run in parallel to collect data to subsequently submit to Elasticsearch's Bulk API. This increases indexing performance, but fills the Elasticsearch bulk requests queue faster. This setting should be used together with the Maximum bulk request size setting (see above) and needs to accommodate the resource constraints of both the Elasticsearch hosts and the hosts running the GitLab Golang-based indexer either from the `gitlab-rake` command or the Sidekiq tasks. |
| `Client request timeout` | Elasticsearch HTTP client request timeout value in seconds. `0` means using the system default timeout value, which depends on the libraries that GitLab application is built upon. |
Advanced Search only provides cross-group code/commit search (global) if all name-spaces are indexed. In this particular scenario where only a subset of namespaces are indexed, a global search does not provide a code or commit scope. This is possible only in the scope of an indexed namespace. There is no way to code/commit search in multiple indexed namespaces (when only a subset of namespaces has been indexed). For example if two groups are indexed, there is no way to run a single code search on both. You can only run a code search on the first group and then on the second.
You can improve the language support for Chinese and Japanese languages by utilizing [`smartcn`](https://www.elastic.co/guide/en/elasticsearch/plugins/current/analysis-smartcn.html) and/or [`kuromoji`](https://www.elastic.co/guide/en/elasticsearch/plugins/current/analysis-kuromoji.html) analysis plugins from Elastic.
1. Install the desired plugins, please refer to [Elasticsearch documentation](https://www.elastic.co/guide/en/elasticsearch/plugins/7.9/installation.html) for plugins installation instructions. The plugins must be installed on every node in the cluster, and each node must be restarted after installation. For a list of plugins, see the table later in this section.
| `Enable Chinese (smartcn) custom analyzer: Indexing` | Enables or disables Chinese language support using [`smartcn`](https://www.elastic.co/guide/en/elasticsearch/plugins/current/analysis-smartcn.html) custom analyzer for newly created indices.|
| `Enable Chinese (smartcn) custom analyzer: Search` | Enables or disables using [`smartcn`](https://www.elastic.co/guide/en/elasticsearch/plugins/current/analysis-smartcn.html) fields for Advanced Search. Please only enable this after [installing the plugin](https://www.elastic.co/guide/en/elasticsearch/plugins/current/analysis-smartcn.html), enabling custom analyzer indexing and recreating the index.|
| `Enable Japanese (kuromoji) custom analyzer: Indexing` | Enables or disables Japanese language support using [`kuromoji`](https://www.elastic.co/guide/en/elasticsearch/plugins/current/analysis-kuromoji.html) custom analyzer for newly created indices.|
| `Enable Japanese (kuromoji) custom analyzer: Search` | Enables or disables using [`kuromoji`](https://www.elastic.co/guide/en/elasticsearch/plugins/current/analysis-kuromoji.html) fields for Advanced Search. Please only enable this after [installing the plugin](https://www.elastic.co/guide/en/elasticsearch/plugins/current/analysis-kuromoji.html), enabling custom analyzer indexing and recreating the index.|
The idea behind this reindexing method is to leverage the [Elasticsearch reindex API](https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-reindex.html)
and Elasticsearch index alias feature to perform the operation. We set up an index alias which connects to a
`primary` index which is used by GitLab for reads/writes. When reindexing process starts, we temporarily pause
the writes to the `primary` index. Then, we create another index and invoke the Reindex API which migrates the
> - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/34069) in GitLab 13.2.
> - A scheduled index deletion and the ability to cancel it was [introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/38914) in GitLab 13.3.
The slice multiplier calculates the [number of slices during reindexing](https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-reindex.html#docs-reindex-slice).
| [`sudo gitlab-rake gitlab:elastic:index_projects`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/tasks/gitlab/elastic.rake) | Iterates over all projects, and queues Sidekiq jobs to index them in the background. It can only be used after the index is created. |
| [`sudo gitlab-rake gitlab:elastic:index_projects_status`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/tasks/gitlab/elastic.rake) | Determines the overall status of the indexing. It is done by counting the total number of indexed projects, dividing by a count of the total number of projects, then multiplying by 100. |
| [`sudo gitlab-rake gitlab:elastic:clear_index_status`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/tasks/gitlab/elastic.rake) | Deletes all instances of IndexStatus for all projects. Note that this command results in a complete wipe of the index, and it should be used with caution. |
| [`sudo gitlab-rake gitlab:elastic:create_empty_index`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/tasks/gitlab/elastic.rake) | Generates empty indexes (the default index and a separate issues index) and assigns an alias for each on the Elasticsearch side only if it doesn't already exist. |
| [`sudo gitlab-rake gitlab:elastic:delete_index`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/tasks/gitlab/elastic.rake) | Removes the GitLab indexes and aliases (if they exist) on the Elasticsearch instance. |
| [`sudo gitlab-rake gitlab:elastic:recreate_index`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/tasks/gitlab/elastic.rake) | Wrapper task for `gitlab:elastic:delete_index` and `gitlab:elastic:create_empty_index`. |
| [`sudo gitlab-rake gitlab:elastic:index_snippets`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/tasks/gitlab/elastic.rake) | Performs an Elasticsearch import that indexes the snippets data. |
| [`sudo gitlab-rake gitlab:elastic:projects_not_indexed`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/tasks/gitlab/elastic.rake) | Displays which projects are not indexed. |
| [`sudo gitlab-rake gitlab:elastic:reindex_cluster`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/tasks/gitlab/elastic.rake) | Schedules a zero-downtime cluster reindexing task. This feature should be used with an index that was created after GitLab 13.0. |
| [`sudo gitlab-rake gitlab:elastic:mark_reindex_failed`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/tasks/gitlab/elastic.rake) | Mark the most recent re-index job as failed. |
| [`sudo gitlab-rake gitlab:elastic:list_pending_migrations`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/tasks/gitlab/elastic.rake) | List pending migrations. Pending migrations include those that have not yet started, have started but not finished, and those that are halted. |
| [`sudo gitlab-rake gitlab:elastic:estimate_cluster_size`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/tasks/gitlab/elastic.rake) | Get an estimate of cluster size based on the total repository size. |
| `UPDATE_INDEX` | Boolean | Tells the indexer to overwrite any existing index data (true/false). |
| `ID_TO` | Integer | Tells the indexer to only index projects less than or equal to the value. |
| `ID_FROM` | Integer | Tells the indexer to only index projects greater than or equal to the value. |
### Indexing a specific project
Because the `ID_TO` and `ID_FROM` environment variables use the `or equal to` comparison, you can index only one project by using both these variables with the same project ID number:
### Guidance on choosing optimal cluster configuration
For basic guidance on choosing a cluster configuration you may refer to [Elastic Cloud Calculator](https://cloud.elastic.co/pricing). You can find more information below.
- Generally, you want to use at least a 2-node cluster configuration with one replica, which allows you to have resilience. If your storage usage is growing quickly, you may want to plan horizontal scaling (adding more nodes) beforehand.
- It's not recommended to use HDD storage with the search cluster, because it takes a hit on performance. It's better to use SSD storage (NVMe or SATA SSD drives for example).
- You can use the [GitLab Performance Tool](https://gitlab.com/gitlab-org/quality/performance) to benchmark search performance with different search cluster sizes and configurations.
-`Heap size` should be set to no more than 50% of your physical RAM. Additionally, it shouldn't be set to more than the threshold for zero-based compressed oops. The exact threshold varies, but 26 GB is safe on most systems, but can also be as large as 30 GB on some systems. See [Heap size settings](https://www.elastic.co/guide/en/elasticsearch/reference/current/important-settings.html#heap-size-settings) and [Setting JVM options](https://www.elastic.co/guide/en/elasticsearch/reference/current/jvm-options.html) for more details.
- A good guideline is to ensure you keep the number of shards per node below 20 per GB heap it has configured. A node with a 30GB heap should therefore have a maximum of 600 shards, but the further below this limit you can keep it the better. This generally helps the cluster stay in good health.
- Another consideration is the number of documents. To determine the number of shards to use, sum the numbers in the **Menu > Admin > Dashboard > Statistics** pane (the number of documents to be indexed), divide by 5 million, and add 5. For example:
-`refresh_interval` is a per index setting. You may want to adjust that from default `1s` to a bigger value if you don't need data in real-time. This changes how soon you see fresh results. If that's important for you, you should leave it as close as possible to the default value.
- You might want to raise [`indices.memory.index_buffer_size`](https://www.elastic.co/guide/en/elasticsearch/reference/current/indexing-buffer.html) to 30% or 40% if you have a lot of heavy indexing operations.
- The `Number of Elasticsearch shards` setting usually corresponds with the number of CPUs available in your cluster. For example, if you have a 3-node cluster with 4 cores each, this means you benefit from having at least 3*4=12 shards in the cluster. It's only possible to change the shards number by using [Split index API](https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-split-index.html) or by reindexing to a different index with a changed number of shards.
- The `Number of Elasticsearch replicas` setting should most of the time be equal to `1` (each shard has 1 replica). Using `0` is not recommended, because losing one node corrupts the index.
1. Indexing large Git repositories can take a while. To speed up the process, you can [tune for indexing speed](https://www.elastic.co/guide/en/elasticsearch/reference/current/tune-for-indexing-speed.html#tune-for-indexing-speed):
- You can temporarily disable [`refresh`](https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-refresh.html), the operation responsible for making changes to an index available to search.
- You can set the number of replicas to 0. This setting controls the number of copies each primary shard of an index will have. Thus, having 0 replicas effectively disables the replication of shards across nodes, which should increase the indexing performance. This is an important trade-off in terms of reliability and query performance. It is important to remember to set the replicas to a considered value after the initial indexing is complete.
In our experience, you can expect a 20% decrease in indexing time. After completing indexing in a later step, you can return `refresh` and `number_of_replicas` to their desired settings.
Whenever a change or deletion is made to an indexed GitLab object (a merge request description is changed, a file is deleted from the default branch in a repository, a project is deleted, etc), a document in the index is deleted. However, since these are "soft" deletes, the overall number of "deleted documents", and therefore wasted space, increases. Elasticsearch does intelligent merging of segments in order to remove these deleted documents. However, depending on the amount and type of activity in your GitLab installation, it's possible to see as much as 50% wasted space in the index.
In general, we recommend letting Elasticsearch merge and reclaim space automatically, with the default settings. From [Lucene's Handling of Deleted Documents](https://www.elastic.co/blog/lucenes-handling-of-deleted-documents "Lucene's Handling of Deleted Documents"), _"Overall, besides perhaps decreasing the maximum segment size, it is best to leave Lucene's defaults as-is and not fret too much about when deletes are reclaimed."_
- Consider reducing the `index.merge.policy.max_merged_segment` size from the default 5 GB to maybe 2 GB or 3 GB. Merging only happens when a segment has at least 50% deletions. Smaller segment sizes will allow merging to happen more frequently.
- You can also adjust `index.merge.policy.reclaim_deletes_weight`, which controls how aggressively deletions are targeted. But this can lead to costly merge decisions, so we recommend not changing this unless you understand the tradeoffs.
- Do not do a [force merge](https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-forcemerge.html "Force Merge") to remove deleted documents. A warning in the [documentation](https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-forcemerge.html "Force Merge") states that this can lead to very large segments that may never get reclaimed, and can also cause significant performance or availability issues.
## Index large instances with dedicated Sidekiq nodes or processes
Indexing a large instance can be a lengthy and resource-intensive process that has the potential
of overwhelming Sidekiq nodes and processes. This negatively affects the GitLab performance and
availability.
As GitLab allows you to start multiple Sidekiq processes, you can create an
additional process dedicated to indexing a set of queues (or queue group). This way, you can
ensure that indexing queues always have a dedicated worker, while the rest of the queues have
another dedicated worker to avoid contention.
For this purpose, use the [queue selector](../administration/operations/extra_sidekiq_processes.md#queue-selector)
option that allows a more general selection of queue groups using a [worker matching query](../administration/operations/extra_sidekiq_routing.md#worker-matching-query).
To handle these two queue groups, we generally recommend one of the following two options. You can either:
- [Use two queue groups on one single node](#single-node-two-processes).
- [Use two queue groups, one on each node](#two-nodes-one-process-for-each).
For the steps below, consider:
-`feature_category=global_search` as an indexing queue group with its own Sidekiq process.
-`feature_category!=global_search` as a non-indexing queue group that has its own Sidekiq process.
### Single node, two processes
To create both an indexing and a non-indexing Sidekiq process in one node:
1. On your Sidekiq node, change the `/etc/gitlab/gitlab.rb` file to:
```ruby
sidekiq['enable'] = true
sidekiq['queue_selector'] = true
sidekiq['queue_groups'] = [
"feature_category=global_search",
"feature_category!=global_search"
]
```
1. Save the file and [reconfigure GitLab](../administration/restart_gitlab.md)
for the changes to take effect.
WARNING:
When starting multiple processes, the number of processes cannot exceed the number of CPU
cores you want to dedicate to Sidekiq. Each Sidekiq process can use only one CPU core, subject
to the available workload and concurrency settings. For more details, see how to
Beyond that, check via the [Elasticsearch Search API](https://www.elastic.co/guide/en/elasticsearch/reference/current/search-search.html) to see if the data shows up on the Elasticsearch side:
It is important to understand at which level the problem is manifesting (UI, Rails code, Elasticsearch side) to be able to [troubleshoot further](../administration/troubleshooting/elasticsearch.md#search-results-workflow).
This was [fixed](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/35936) in GitLab 13.2 and the Rake task is not available for versions greater than that.
When performing the initial indexing of blobs, we lock all projects until the project finishes indexing. It could happen that an error during the process causes one or multiple projects to remain locked. To unlock them, run:
If you have this exception (just like in the case above but the actual message is different) please check if you have the correct Elasticsearch version and you met the other [requirements](#system-requirements).
There is also an easy way to check it automatically with `sudo gitlab-rake gitlab:check` command.
This exception is seen when your Elasticsearch cluster is configured to reject requests above a certain size (10MiB in this case). This corresponds to the `http.max_content_length` setting in `elasticsearch.yml`. Increase it to a larger size and restart your Elasticsearch cluster.
AWS has [fixed limits](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/limits.html#network-limits) for this setting ("Maximum size of HTTP request payloads"), based on the size of the underlying instance.
**For a single node Elasticsearch cluster the functional cluster health status is yellow** (never green) because the primary shard is allocated but replicas cannot be as there is no other node to which Elasticsearch can assign a replica. This also applies if you are using the [Amazon OpenSearch](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/aes-handling-errors.html#aes-handling-errors-yellow-cluster-status) service.
Setting the number of replicas to `0` is discouraged (this is not allowed in the GitLab Elasticsearch Integration menu). If you are planning to add more Elasticsearch nodes (for a total of more than 1 Elasticsearch) the number of replicas needs to be set to an integer value larger than `0`. Failure to do so results in lack of redundancy (losing one node corrupts the index).
If you have a **hard requirement to have a green status for your single node Elasticsearch cluster**, please make sure you understand the risks outlined in the previous paragraph and then run the following query to set the number of replicas to `0`(the cluster no longer tries to create any shard replicas):
You probably have not used either `http://` or `https://` as part of your value in the **"URL"** field of the Elasticsearch Integration Menu. Please make sure you are using either `http://` or `https://` in this field as the [Elasticsearch client for Go](https://github.com/olivere/elastic) that we are using [needs the prefix for the URL to be accepted as valid](https://github.com/olivere/elastic/commit/a80af35aa41856dc2c986204e2b64eab81ccac3a).
After you have corrected the formatting of the URL, delete the index (via the [dedicated Rake task](#gitlab-advanced-search-rake-tasks)) and [reindex the content of your instance](#enable-advanced-search).
There is a [more structured, lower-level troubleshooting document](../administration/troubleshooting/elasticsearch.md) for when you experience other issues, including poor performance.
The `code_analyzer` pattern and filter configuration is being evaluated for improvement. We have fixed [most edge cases](https://gitlab.com/groups/gitlab-org/-/epics/3621#note_363429094) that were not returning expected search results due to our pattern and filter configuration.
In GitLab 13.9, a change was made where [binary file names are being indexed](https://gitlab.com/gitlab-org/gitlab/-/issues/301083). However, without indexing all projects' data from scratch, only binary files that are added or updated after the GitLab 13.9 release are searchable.
### Indexing fails with `error: elastic: Error 429 (Too Many Requests)`
If `ElasticCommitIndexerWorker` Sidekiq workers are failing with this error during indexing, it usually means that Elasticsearch is unable to keep up with the concurrency of indexing request. To address change the following settings:
- To decrease the indexing throughput you can decrease `Bulk request concurrency` (see [Advanced Search settings](#advanced-search-configuration)). This is set to `10` by default, but you change it to as low as 1 to reduce the number of concurrent indexing operations.
- If changing `Bulk request concurrency` didn't help, you can use the [queue selector](../administration/operations/extra_sidekiq_processes.md#queue-selector) option to [limit indexing jobs only to specific Sidekiq nodes](#index-large-instances-with-dedicated-sidekiq-nodes-or-processes), which should reduce the number of indexing requests.
See [Identity and Access Management in Amazon OpenSearch Service](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/ac.html) for details.
