Matching across Multiple documents with ElasticSearch - php

Question

I am relatively new to ElasticSearch. I am using it as a search platform for pdf documents. I break the PDFs into text-pages and enter each one as an elasticSearch record with it's corresponding page ID, parent info, etc.
What I'm finding difficult is matching a given query not only to a single document in ES, but making it match any document with the same parent ID. So if two terms are searched, if the terms existed on page 1 and 7 of the actual PDF document (2 separate entries into ES), I want to match this result.
Essentially my goal is to be able to search through the multiple pages of a single PDF, matching happening on any of the document-pages in the PDF, and to return a list of matching PDF documents for the search result, instead of matching "pages"

Answer 1

You will need to use the "has_child" query on pages. I'm assumed that you're already defined the mapping for parent/child relationship of documents and pages. Then you can write a "has_child" query that search on pages (child type) but return PDF documents (parent type):
{
"query": {
"has_child": {
"type": "your_pages_type",
"score_type": "max", // read document for more
"query": {
"query_string": {
"query": "some text to search",
"fields": [
"your_pages_body"
],
"default_operator": "and" // "and" if you want to search all words, "or" if you want to search any of words in query
}
}
}
}
}

Answer 2

It's somewhat tricky. First of all, you will have to split your query into terms yourself. Having a list of terms (let's say foo, bar and baz, you can create a bool query against type representing PDFs (parent type) that would look like this:
{
"bool" : {
"must" : [{
"has_child" : {
"type": "page",
"query": {
"match": {
"page_body": "foo"
}
}
}
}, {
"has_child" : {
"type": "page",
"query": {
"match": {
"page_body": "bar"
}
}
}
}, {
"has_child" : {
"type": "page",
"query": {
"match": {
"page_body": "baz"
}
}
}
}]
}
}
This query will find you all PDFs that contain at least one page with each term.