Does elasticsearch support conditional queries?

Question

I know that solr supports if conditions in the query (e.g., fl=if(min(2,myField),2,myField)). I am not able to find similar functionality in elasticsearch. The closest I can find is script fields.

Does elasticsearch support nested function queries like min(max(myField,0),1)?
If so, does it support such queries for sorting as well, like sort=min(max(myField,0),1)?

javanna · Accepted Answer · 2013-07-21 10:42:38Z

5

Scripting is what you're looking for. The default scripting language is mvel, but you can easily install plugins that support other languages, like javascript, groovy, python. You can also write your own native script in Java.

You can use scripts in different apis, here are some examples:

script fields as you mentioned, to get back fields that are not in your documents but created on-the-fly
script based sorting, to sort your documents based on the result of a script
script filter, to filter based on a script
boosting using custom score query and custom filters score query
making facets

It's possible to preload scripts placing them on file system, from the documentation page:

Scripts can always be provided as part of the relevant API, but they can also be preloaded by placing them under config/scripts and then referencing them by the script name (instead of providing the full script). This helps reduce the amount of data passed between the client and the nodes.

The name of the script is derived from the hierarchy of directories it exists under, and the file name without the lang extension. For example, a script placed under config/scripts/group1/group2/test.py will be named group1_group2_test.

Only native scripts written in java have to implement an interface. In case of either mvel, javascript python or groovy, you can just write the script that you need on file instead of passing it together with the relevant api and refer to it using its name.

edited Jul 21, 2013 at 10:42

answered Jul 19, 2013 at 8:23

javanna

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2 Comments

Karthick Over a year ago

@javana Great. In most of the examples, I see simple scripts like script" : "doc['field_name'].value * factor" . Have you come across something that talks about how to plugin an myPython.py file and goes into details like where the .py/.js file should be put, what methods & signatures it needs to implement etc.?

javanna Over a year ago

It's hard for me to follow here but I saw you posted on the elasticsearch google group a specific question with more details. I would consider this question answered given its title and content, but you are free to create a new one with a detailed description whenever you feel like you need more help.

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