How to detect unused indexes on MongoDB collections?

db.your_collection.aggregate([{$indexStats:{}}]).pretty()

ops displays operations per second on a specific index. If ops is very low compared to other indexes you can drop the index.

#mongodb #mongo #index #unused_indexes

Elasticsearch gives below error:

Config: Error 403 Forbidden: blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];: [cluster_block_exception] blocked by:   [FORBIDDEN/12/index read-only / allow delete (api)];

This error may happen when server storage is totally full and elasticsearch puts your indexes in read only mode. If you have enough
space now and are sure there is no other matter for elasticsearch and it behaves normally, remove read only mode from index block:

curl -XPUT -H "Content-Type: application/json" https://localhost:9200/.monitoring-*/_settings -d '{"index.blocks.                       read_only_allow_delete": null}'

#elasticsearch #read_only #index #cluster_block_exception