[Bug] Count queries scrolls thru all elasticsearch index

[gfmellado]

Hello everyone! We have an issue: when we filter by native fields (like date, source, severity, etc.) the count query response time takes a normal amount of time (fast), but when we filter by custom fields, we think it scrolls thru all index database (elasticsearch) and two possible scenarios occur:

1. when the count number is greater than the query threshold (query.limitedCountThreshold: 1000) it stops when it reaches that limit.
2. when the count number is lower than the query threshold (query.limitedCountThreshold: 1000) it ends up scrolling thru all index database in order to get the definitive number.

The second scenario takes a lot of time and really stresses the platform.

What can we do to improve this situation? If we do a reindex, does custom fields get reindexed?

Thanks in advance for any help.