Number of documents in an index


I'm doing some load testing and I found something strange on ElasticSearch (2.2.0).

I feed a single index with 104.690.000 documents. This index has only 2 shards.

When I check the output of /_cat/indices, I get this:

green open customer-data-100m-v1 2 1 104690000 0 171.2gb 88.3gb

But when I do a GET /customer-data-100m-v1/customer/_count, I get half number of documents:

{ "count": 52345000, "_shards": { "total": 2, "successful": 2, "failed": 0 } }

Is this somehow related to the number of shards? Shouldn't I get the same count?

What happens if you GET /customer-data-100m-v1/_count instead of GET /customer-data-100m-v1/customer/_count

I get the same output.

So, it looks like it's not related to the number of shards, because I loaded another index with +100mi docs, but now with 4 shards, and I also get half count.

green open customer-data-100m-4shards-v1 4 1 107180000 0 171gb 85.5gb

{ "count": 53590000, "_shards": { "total": 4, "successful": 4, "failed": 0 } }

How about

GET /customer-data-100m-v1/_stats

I deleted a few docs to try something else, so here are the updated results, including the part of the output of /_stats

green open customer-data-100m-v1         2 1 104677426 12574 170.9gb    88gb 
   "count": 52338713,
   "_shards": {
      "total": 2,
      "successful": 2,
      "failed": 0

The the output of /customer-data-100m-v1/_stats is at

_stats gave you the number you expected

"indices": {
      "customer-data-100m-v1": {
         "primaries": {
            "docs": {
               "count": 104677426,
               "deleted": 12574

but it's strange that _count did not give you the same number. I checked many of my indices, and all gave the same number for both _count and _stats

Yes, but what is count then?

   "count": 52338713,

You previous _count showed a total of two shards while the _stats showed 4 shards. Could you try

GET _cat/count/customer-data-100m-v1

At an educated guess, _cat include replica documents while _stats doesn't.



GET /_cat/count/customer-data-100m-v1

1458576068 17:01:08 52338713