ElasticSearch (cURL REST API request) not giving results expected - elasticsearch

Question

I use this command, which should match all documents:
curl -XGET 'localhost:9200/users/_search?pretty' -H 'Content-Type: application/json' -d'
{
"query": { "match_all": {} }
}
'
I get this response:
{
"took" : 0,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : 0,
"max_score" : null,
"hits" : [ ]
}
}
But I'm 99.9% sure I have documents on that index. If I am right, why isn't it showing the matches? If I am wrong, how can I confirm this?

Answer 1

You should be able to determine what's happening if you know (a) where all your documents are being stored and (b) what the server thinks the 'users' index actually is.
For the first question, you can hit the _cat/indices endpoint to see how many documents you have in each index (the "docs.count" column):
$curl -XGET 'http://localhost:9200/_cat/indices?v'
health status index pri rep docs.count docs.deleted store.size pri.store.size
green open query 1 0 0 0 159b 159b
green open some_index 1 0 54 0 24.7kb 24.7kb
green open autocomplete 1 0 0 0 159b 159b
green open test_index 2 0 10065 4824 7.9mb 7.9mb
For the second question, check the aliases defined on your server. It's possible that "users" has been defined as an alias to an index that doesn't have any documents, or it's possible that a filtered alias has been defined on that index with a filter that is excluding all of your documents (many aliases have date-related filters that will exclude all documents outside of a very specific date range). To check for the presence of aliases you can use
$curl -XGET 'http://localhost:9200/_aliases?pretty=true'