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.
NOTE: **Note:**
This step is optional but may help significantly speed up large indexing operations.
```shell
curl --request PUT localhost:9200/gitlab-production/_settings --header'Content-Type: application/json'--data'{
1. Enable replication and refreshing again after indexing (only if you previously disabled it):
```shell
curl --request PUT localhost:9200/gitlab-production/_settings --header'Content-Type: application/json'--data'{
"index" : {
"number_of_replicas" : 1,
"refresh_interval" : "1s"
} }'
```
A force merge should be called after enabling the refreshing above.
For Elasticsearch 6.x, the index should be in read-only mode before proceeding with the force merge:
```shell
curl --request PUT localhost:9200/gitlab-production/_settings --header'Content-Type: application/json'--data'{
"settings": {
"index.blocks.write": true
} }'
```
Then, initiate the force merge:
```shell
curl --request POST 'localhost:9200/gitlab-production/_forcemerge?max_num_segments=5'
```
After this, if your index is in read-only mode, switch back to read-write:
```shell
curl --request PUT localhost:9200/gitlab-production/_settings --header'Content-Type: application/json'--data'{
"settings": {
"index.blocks.write": false
} }'
```
1. After the indexing has completed, enable [**Search with Elasticsearch**](#enabling-elasticsearch).
## Zero downtime reindexing
The idea behind this reindexing method is to leverage Elasticsearch index alias
...
...
@@ -661,6 +503,168 @@ For basic guidance on choosing a cluster configuration you may refer to [Elastic
- 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 will benefit from having at least 3*4=12 shards in the cluster. Please note, 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 will have 1 replica). Using `0` is not recommended, because losing one node will corrupt the index.
### Indexing large instances
This section may be helpful in the event that the other
[basic instructions](#enabling-elasticsearch) cause problems
due to large volumes of data being indexed.
CAUTION: **Warning:**
Indexing a large instance will generate a lot of Sidekiq jobs.
Make sure to prepare for this task by having a [Scalable and Highly Available
Setup](../administration/reference_architectures/index.md) or creating [extra
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.
NOTE: **Note:**
This step is optional but may help significantly speed up large indexing operations.
```shell
curl --request PUT localhost:9200/gitlab-production/_settings --header'Content-Type: application/json'--data'{
1. Enable replication and refreshing again after indexing (only if you previously disabled it):
```shell
curl --request PUT localhost:9200/gitlab-production/_settings --header'Content-Type: application/json'--data'{
"index" : {
"number_of_replicas" : 1,
"refresh_interval" : "1s"
} }'
```
A force merge should be called after enabling the refreshing above.
For Elasticsearch 6.x, the index should be in read-only mode before proceeding with the force merge:
```shell
curl --request PUT localhost:9200/gitlab-production/_settings --header'Content-Type: application/json'--data'{
"settings": {
"index.blocks.write": true
} }'
```
Then, initiate the force merge:
```shell
curl --request POST 'localhost:9200/gitlab-production/_forcemerge?max_num_segments=5'
```
After this, if your index is in read-only mode, switch back to read-write:
```shell
curl --request PUT localhost:9200/gitlab-production/_settings --header'Content-Type: application/json'--data'{
"settings": {
"index.blocks.write": false
} }'
```
1. After the indexing has completed, enable [**Search with Elasticsearch**](#enabling-elasticsearch).
### Deleted documents
Whenever a change or deletion is made to an indexed GitLab object (a merge request description is changed, a file is deleted from the master 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.
