How delete document works?

Elastic Stack Elasticsearch
1

I heard when we delete a document it remains on disks and next queries will filter deleted documents, is it true?

2

Segments are immutables so yes technically they are still on the disk until the next merge.

3

Yes its true, when you issue this command : "GET /_cat/indices?v " on sense , you will see the doc.deleted increases.

4

So the search performance decreases? Until next merge?

5

You should not really notice.

6

See https://www.elastic.co/blog/lucenes-handling-of-deleted-documents for more details.