How to increase index.max_result_window from Liferay

Note: please note that Liferay has renamed its Liferay Experience Could offerings to Liferay SaaS (formerly LXC) and Liferay PaaS (formerly LXC-SM).

Issue

When the number of results is more than the default (10000) the following message appears on the Liferay portal logs:

ERROR [http-nio-8080-exec-99][ElasticsearchIndexSearcher:165] java.lang.RuntimeException: org.elasticsearch.ElasticsearchStatusException: ElasticsearchStatusException[Elasticsearch exception [type=search_phase_execution_exception, reason=all shards failed]]; nested: ElasticsearchException[Elasticsearch exception [type=illegal_argument_exception, reason=Result window is too large, from + size must be less than or equal to: [10000] but was [11000]. See the scroll api for a more efficient way to request large data sets. This limit can be set by changing the [index.max_result_window] index level setting.]]; nested: ElasticsearchException[Elasticsearch exception [type=illegal_argument_exception, reason=Result window is too large, from + size must be less than or equal to: [10000] but was [11000]. See the scroll api for a more efficient way to request large data sets. This limit can be set by changing the [index.max_result_window] index level setting.]];

java.lang.RuntimeException: org.elasticsearch.ElasticsearchStatusException: ElasticsearchStatusException[Elasticsearch exception [type=search_phase_execution_exception, reason=all shards failed]]; nested: ElasticsearchException[Elasticsearch exception [type=illegal_argument_exception, reason=Result window is too large, from + size must be less than or equal to: [10000] but was [11000]. See the scroll api for a more efficient way to request large data sets. This limit can be set by changing the [index.max_result_window] index level setting.]]; nested: ElasticsearchException[Elasticsearch exception [type=illegal_argument_exception, reason=Result window is too large, from + size must be less than or equal to: [10000] but was [11000]. See the scroll api for a more efficient way to request large data sets. This limit can be set by changing the [index.max_result_window] index level setting.]];

Environment

Liferay DXP 7.2 (with Elasticsearch 7 connector installed)
Liferay DXP 7.3
Liferay DXP 7.4

Resolution

Configuring `index.max_result_window` in Liferay DXP can be done by following the below:

Go to Menu --> Control Panel --> System Settings --> Search --> Elasticsearch 7
if you see a "Max Result Window" field, use it to change to the desired value
if you don't see a "Max Result Window" field, use the "Additional Index Configurations" field by entering something like below:
```
{ 

"index.max_result_window" :x

}
```
`x` should be any value based on the portal. In the below image, it is 25000.
Requires full reindex post configurational changes. (note: might not be the case when using the "Max Result Window" field)
Execute re-index the search indexes and spell check indexes from the Index Actions tab of Control Panel → Configuration → Search

Additional Information

In case you need to perform this in a cloud environment, please check Automate scripts for search service in Liferay PaaS
"Result window is too large" error on Elasticsearch 6