ElasticSearch 5.x - A practical overview of ES features

mini_deb_conf.txt

GET /

POST /my-index/my-doc/1
{
  "body": "foo"
}


GET /my_index/my_doc/_search
{
  "query": {
    "match": {
      "body": "bar"
    }
  }
}

PUT /library
{
  "settings": {
    "index.number_of_shards": 1,
    "index.number_of_replicas": 0
  }
}

#__________________________
#
# Bulk indexing and Search
#
#__________________________
#
# When you have a lot of docs to index you should
# use bulk API of ES

POST /library/books/_bulk
{"index": {"_id": 1}}
{"title": "The quick brown fox", "price": 5, "colors": ["red", "green", "blue"]}
{"index": {"_id": 2}}
{"title": "The quick brown fox jumps over the lazy dog", "price": 15, "colors": ["blue", "yellow"]}
{"index": {"_id": 3}}
{"title": "The quick brown fox jumps over the lazy dog", "price": 8, "colors": ["red", "blue"]}
{"index": {"_id": 4}}
{"title": "Brown fox brown dog", "price": 2, "colors": ["black", "yellow", "red", "blue"]}
{"index": {"_id": 5}}
{"title": "Lazy dog", "price": 9, "colors": ["red", "blue", "green"]}


GET library/books/_search


GET library/books/_search
{
  "query": {
    "match": {
      "title": "fox"
    }
  }
}


# How about 'quick' and 'dog'?
GET library/books/_search
{
  "query": {
    "match": {
      "title": "quick dog"
    }
  }
}


# let's be more strict when we search
GET library/books/_search
{
  "query": {
    "match_phrase": {
      "title": "quick brown"
    }
  }
}

# Results are ranked based on relevance score (_score)
GET library/books/_search
{
  "query": {
    "match": {
      "title": "quick"
    }
  }
}

#_____________________
# We can also do some boolean query combination
#
# Let's find all docs with "quick" and "lazy dog"


GET /library/books/_search
{
  "query": {
    "bool": {
      "must": [
        {
          "match": {
            "title": "quick"
          }
        },
        {
          "match_phrase": {
            "title": "lazy dog"
          }
        }
      ]
    }
  }
}

#___________________________________________
# or we can negate the query clause

GET /library/books/_search
{
  "query": {
    "bool": {
      "must_not": [
        {
          "match": {
            "title": "lazy"
          }
        },
        {
          "match_phrase": {
            "title": "quick dog"
          }
        }
      ]
    }
  }
}

#___________________________________________________
# Combinations can be boosted for different effects

GET /library/books/_search
{
  "query": {
    "bool": {
      "should": [
        {
          "match": {
            "title": {
              "query": "quick dog"
            }
          }
        },
        {
          "match_phrase": {
            "title": {
              "query": "lazy dog",
              "boost": 3
            }
          }
        }
      ]
    }
  }
}


#__________________________
# Sometimes, for better distinction in the UI side
# we tend to highlight the matched terms

GET /library/books/_search
{
  "query": {
    "bool": {
      "should": [
        {
          "match": {
            "title": {
              "query": "quick dog"
            }
          }
        },
        {
          "match_phrase": {
            "title": {
              "query": "lazy dog",
              "boost": 3
            }
          }
        }
      ]
    }
  },
  "highlight": {
      "fields": {
        "title": {}
      }
    }
}
# More info on: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-highlighting.html



#___________________________________
# We can also perform filtering
# Filtering is faster than quering

GET /library/books/_search
{
  "query": {
    "bool": {
      "must": [
        {
          "match": {
            "title": "dog"
          }
        }
      ],
      "filter": {
        "range": {
          "price": {
            "gte": 5,
            "lte": 10
          }
        }
      }
    }
  }
}

# Filtering can be applied without query clause
GET /library/books/_search
{
  "query": {
    "bool": {
      "filter": {
        "range": {
          "price": {
            "gte": 5
          }
        }
      }
    }
  }
}
# More info on: https://www.elastic.co/guide/en/elasticsearch/reference/current/query-filter-context.html

#_________________________________________________________ 
# How did that work? 
# We need to know and understand how to tune elastic search,
# in order to make it search in a "managed" manner
# _analysis

# Analysis = tokenization + token filters

GET /library/_analyze
{
  "tokenizer": "standard",
  "text": "Brown fox brown dog"
}

# Token filters can manipulate these token
GET /library/_analyze
{
  "tokenizer": "standard",
  "filter": ["lowercase"], 
  "text": "Brown fox brown dog"
}

# There is a wide array of toke filters
GET /library/_analyze
{
  "tokenizer": "standard",
  "filter": ["lowercase", "unique"], 
  "text": "Brown fox brown dog"
}

#___________________________________________________
# A tokenizer + 0 or more token filters = Analyzers

GET /library/_analyze
{
  "analyzer": "standard",
  "text": "Brown fox brown dog"
}


#___________________________________________________
# Understanding analysis is very important, because
# the emmitted tokens can significatly change the results
# helps your queries be more relevant

GET /library/_analyze
{
  "tokenizer": "standard",
  "filter": ["lowercase"], 
  "text": "ThE quick.brown_FOx Jumped! $19.95 @ 3.0"
}

GET /library/_analyze
{
  "tokenizer": "letter",
  "filter": ["lowercase"], 
  "text": "ThE quick.brown_FOx Jumped! $19.95 @ 3.0"
}


# Another example is with uax_url_email tokenizer
GET /library/_analyze
{
  "tokenizer": "standard",
  "text": "example@example.com website: https:/elastic.co"
}

GET /library/_analyze
{
  "tokenizer": "uax_url_email",
  "text": "example@example.com website: https://elastic.co"
}

# More info on: https://www.elastic.co/guide/en/elasticsearch/reference/5.6/analysis.html


#_____________________________________
# Aggregations can be used to explore
# and extract insights from your data

GET /library/books/_search
{
  "size": 0,
  "aggs": {
    "popular-colors": {
      "terms": {
        "field": "colors.keyword"
      }
    }
  }
}

# We can use aggs alongside with search
GET /library/books/_search
{
  "query": {
    "match": {
      "title": "dog"
    }
  },
  "aggs": {
    "popular-colors": {
      "terms": {
        "field": "colors.keyword"
      }
    }
  }
}

# Aggregations can be nested, and be used to perform calculations 

GET /library/books/_search
{
  "size": 0,
  "aggs": {
    "popular-colors": {
      "terms": {
        "field": "colors.keyword"
      },
      "aggs": {
        "avg-price-per-color": {
          "avg": {
            "field": "price"
          }
        }
      }
    }
  }
}


# Documents can be updated at any time by re-indexing them

POST /library/books/4
{
  "title": "The Brown fox and a brown dog", 
  "price": 12, 
  "colors": ["black", "red", "blue"]
}

# or by using the _update API, for partial updates

POST /library/books/4/_update
{
  "doc": {
    "price": 6
  }
}

GET /library/books/4



#____________________________________________________
# Elastic search dynamically defines index schema
# when documents are indexed - tries to interfere the data type

GET /library/books/_mapping

# We can define the mapping (schema) when we create the index

PUT /famous-librarians
{
  "settings": {
    "index": {
      "number_of_shards": 2,
      "number_of_replicas": 0,
      "analysis": {
        "analyzer": {
          "my-desc-analyzer": {
            "type": "custom",
            "tokenizer": "uax_url_email",
            "filter": ["lowercase"]
          }
        }
      }
    }
  },
  "mappings": {
    "librarian": {
      "properties": {
        "name":{
          "type": "text"
        },
        "fave-colors": {
          "type": "keyword"
        },
        "birth-date": {
          "type": "date",
          "format": "year_month_day"
        },
        "hometowrn": {
          "type": "geo_point"
        },
        "description": {
          "type": "text",
          "analyzer": "my-desc-analyzer"
        }
      }
    }
  }
}

GET /famous-librarians/_mapping

PUT /famous-librarians/librarian/1
{
  "name": "Filan Fisteku",
  "colors": ["yellow", "black"],
  "birthdate": "1877-11-11",
  "hometown": {
    "lat": 32.456478,
    "lon": -87.421111
  },
  "description": "Pioneered the establishment of libraries in Balkans - filan.fisteku@fiction.com"
}

GET /famous-librarians/librarian/1

# be careful when you do this.

DELETE /library
DELETE /famous-librarians