ElasticSearch Part 3 [Categories of Queries]

In elasticsearch there are two main categories in queries which are :

1. Leaf: It looks for particular value in particular fields like "dell" in the product name. This queries can be used by themselves without being part of the compound queries. And the best thing is it can be used as a part of compound query too for the most advanced queries.

2. Compound: This queries wrap the leaf queries and can wrap other compound queries. It combine multiple queries in logical fashion which means as a Boolean logic. Using this we can also alter the behavior of the queries.

3. Full Text: It is used for running full text search query i.e. looking for every fields in the document. Here values are analyzed when adding and updating the document. It is analyzed like by using the stop words like "the".

4. Term Value: Used to match exact matching values. Usually used for the numbers and date rather then the text. E.g. Finding peoples who are born between 2001 and 2010. Here search queries are not analyzed before executing.

5. Joining Queries: As we know that it is very expensive to perform joining in the distributed system so elasticsearch offers two forms of joins that are designed to scale horizontally they are:

I. Nested Queries
Lets go back, where we had defined a propertise called category in the product document which contains the array of the categories. This nested queries are used in such situation where each object can be queried as a nested query as a indepedent query. 

II. has_child and has_parent queries
has_child returns the parent document which child document match the query similarly has_parent returns the child document which parent document match the query.

6. Geo Queries
I. geo_point:: it is used for latitute/longitude pairs

II. geo_shape:: it is used for the shapes like triangle, polygons etc.