Percolate queries (reverse search) in Elasticsearch - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a percolate query in Elasticsearch?

A percolate query lets you register queries and then check if a document matches any of those stored queries. It's like reverse searching: instead of searching documents with a query, you search queries with a document.

intermediate

How do you register a query for percolation in Elasticsearch?

You index a document into a special index with a percolator field type, where the document contains the query you want to register. This stored query can later be matched against incoming documents.

beginner

What is the main difference between a normal search and a percolate query?

Normal search finds documents matching a query. Percolate query finds queries matching a document. It's like flipping the search direction.

beginner

Which Elasticsearch field type is required to use percolate queries?

The 'percolator' field type is required. It stores queries as documents so they can be matched against incoming documents.

intermediate

Can percolate queries be used for real-time alerting? Why or why not?

Yes, because you can register queries representing conditions to watch for, then percolate incoming documents to see if they match any condition, triggering alerts quickly.

What does a percolate query in Elasticsearch do?

A Finds stored queries that match a given document

B Finds documents that match a given query

C Indexes documents faster

D Deletes stored queries

A percolate query finds stored queries that match a document, reversing the usual search direction.

Which field type must be used to store queries for percolation?

A keyword

B percolator

C text

D nested

The 'percolator' field type is designed to store queries for percolate queries.

What is the main use case of percolate queries?

A Index mapping

B Full text search

C Aggregations

D Reverse search to find matching queries for a document

Percolate queries are used to find which stored queries match a given document.

How do you perform a percolate query in Elasticsearch?

A By deleting documents

B By sending a query to match stored documents

C By sending a document in the query to match stored queries

D By updating the index mapping

You send a document in the percolate query to find stored queries that match it.

Can percolate queries be used for alerting on new data?

A Yes, they can match new documents against stored queries

B No, they are only for indexing

C No, they only work on old data

D Yes, but only for deleting documents

Percolate queries can match new documents against stored queries, useful for alerting.

Explain how percolate queries work in Elasticsearch and give a simple example use case.

Think about searching queries instead of documents.

Describe the steps to register a query for percolation and then use a percolate query to find matches.

Focus on how queries are stored and how documents are matched.