60_cardinality.json

# Find count of distinct colors
GET /cars/transactions/_search
{
    "size" : 0,
    "aggs" : {
        "distinct_colors" : {
            "cardinality" : {
              "field" : "color"
            }
        }
    }
}

# How many colors were sold each month
GET /cars/transactions/_search
{
  "size" : 0,
  "aggs" : {
      "months" : {
        "date_histogram": {
          "field": "sold",
          "interval": "month"
        },
        "aggs": {
          "distinct_colors" : {
              "cardinality" : {
                "field" : "color"
              }
          }
        }
      }
  }
}

# Changing the precision 
GET /cars/transactions/_search
{
    "size" : 0,
    "aggs" : {
        "distinct_colors" : {
            "cardinality" : {
              "field" : "color",
              "precision_threshold" : 100
            }
        }
    }
}

# Precomputing hashes - delete the index
DELETE /cars/

# Precomputing hashes - Add a new mapping which precomputes the hash
PUT /cars/
{
  "mappings": {
    "color": {
      "type": "string",
      "fields": {
          "hash": {
              "type": "murmur3"
          }
      }
    }
  }
}

# Precomputing hashes - Reindex all the data
POST /cars/transactions/_bulk
{ "index": {}}
{ "price" : 10000, "color" : "red", "make" : "honda", "sold" : "2014-10-28" }
{ "index": {}}
{ "price" : 20000, "color" : "red", "make" : "honda", "sold" : "2014-11-05" }
{ "index": {}}
{ "price" : 30000, "color" : "green", "make" : "ford", "sold" : "2014-05-18" }
{ "index": {}}
{ "price" : 15000, "color" : "blue", "make" : "toyota", "sold" : "2014-07-02" }
{ "index": {}}
{ "price" : 12000, "color" : "green", "make" : "toyota", "sold" : "2014-08-19" }
{ "index": {}}
{ "price" : 20000, "color" : "red", "make" : "honda", "sold" : "2014-11-05" }
{ "index": {}}
{ "price" : 80000, "color" : "red", "make" : "bmw", "sold" : "2014-01-01" }
{ "index": {}}
{ "price" : 25000, "color" : "blue", "make" : "ford", "sold" : "2014-02-12" }

# Now the cardinality agg can use `color.hash` for a speed boost
GET /cars/transactions/_search
{
    "size" : 0,
    "aggs" : {
        "distinct_colors" : {
            "cardinality" : {
              "field" : "color.hash"
            }
        }
    }
}