# Understanding bool/must behavior (intersection? )
**URL:** https://discuss.elastic.co/t/understanding-bool-must-behavior-intersection/39286
**Category:** Elasticsearch
**Created:** [January 14, 2016, 11:03pm UTC](https://discuss.elastic.co/t/understanding-bool-must-behavior-intersection/39286 "2016-01-14T23:03:54Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@frankd](https://discuss.elastic.co/u/frankd)
#### Post date: [January 14, 2016, 11:03pm UTC](https://discuss.elastic.co/t/understanding-bool-must-behavior-intersection/39286/1 "2016-01-14T23:03:55Z")
I am having trouble getting a bool : must filter to return what I think it should. (I have a gist at [http://pastebin.com/e4Mbgq48](http://pastebin.com/e4Mbgq48) )
Given that this returns all 3 records:
Bool:{
must
[
conditionA = true
]
}
and this also Returns all 3 records:
Bool:{
must
[
conditionB = true
]
}
why does this Return NO records:
Bool:{
must
[
conditionA = true
,
conditionB = true
]
}
What am I misunderstanding about bool/must? (elasticsearch 1.6)
thanks
Frank
My Conditions are actually nested key value[] properties that I want to use for aggregation.
---
### Author:  [@msimos](https://discuss.elastic.co/u/msimos)
#### Post date: [January 15, 2016, 12:59am UTC](https://discuss.elastic.co/t/understanding-bool-must-behavior-intersection/39286/2 "2016-01-15T00:59:39Z")
A bool filter with a must clause, will only return documents that have **both** conditionA = true and conditionB = true. See this example:
[https://www.elastic.co/guide/en/elasticsearch/guide/master/combining-filters.html#\_nesting\_boolean\_filters](https://www.elastic.co/guide/en/elasticsearch/guide/master/combining-filters.html#_nesting_boolean_filters)
So in your above example, if no documents are returned then there is no document that has **both** conditionA = true and conditionB = true.
---
### Author:  [@frankd](https://discuss.elastic.co/u/frankd)
#### Post date: [January 15, 2016, 5:00pm UTC](https://discuss.elastic.co/t/understanding-bool-must-behavior-intersection/39286/4 "2016-01-15T17:00:27Z")
Mike,
thanks for answering.
But I am confused because I believe my document satisfies both conditions.
I made a new gist ( [http://pastebin.com/G8P0LbLP](http://pastebin.com/G8P0LbLP) )
that
- creates an index
- adds one doc
-contains 3 queries:
- the first filters on must[condition A] (and the one doc is returned)
-the second filters on must[condition B] (the same doc is returned)
-the third filters on condition must[A,B] (no hits)
I have no trouble making this work with non-nested properties, but with the nested
properties in my example I get this unexpected result.
Frank
---
### Author:  [@msimos](https://discuss.elastic.co/u/msimos)
#### Post date: [January 15, 2016, 9:15pm UTC](https://discuss.elastic.co/t/understanding-bool-must-behavior-intersection/39286/5 "2016-01-15T21:15:55Z")
Try using something like this:
```auto
GET test_attribs/_search
{
"query": {
"nested": {
"path": "attributes",
"query": {
"filtered": {
"filter": {
"bool": {
"must": [
{
"term": {
"attributes.key": "Color"
}
},
{
"term": {
"attributes.value": "Blue"
}
}
]
}
}
}
}
}
}
}
```
---
### Author:  [@frankd](https://discuss.elastic.co/u/frankd)
#### Post date: [January 15, 2016, 10:20pm UTC](https://discuss.elastic.co/t/understanding-bool-must-behavior-intersection/39286/6 "2016-01-15T22:20:52Z")
That works for color, but I would like to add a second set of must's to your example with
key='Type' and value='Autoclavable'. (Since there could be blue things with a type of 'somethingElse' and I need to select only blue, autoclavable types )
since the document contains:
nested attributes:[
{u'key': u'Color', u'value': [u'Black', u'Blue', u'Teal']},
{u'key': u'Type', u'value': [u'Autoclavable']}
]
-would that not also eval to true? It doesn't, and I am not sure why not.
Could it be that only one "key/value" element is examined in a pass - so that if I add to your example a term clause
of "term": { "attributes.key": "Type" } it becomes false because key is already "Color" and can't also be "Type"?
Maybe I need a different index structure to do something like
"select a doc from elasticsearch having an attribute where
( key = color and value= 'Blue')
and also having an attribute where
(key = Type and value= 'Autoclavable'
I am ultimately trying to have dynamic filterable attributes.
---
### Author:  [@msimos](https://discuss.elastic.co/u/msimos)
#### Post date: [January 15, 2016, 11:08pm UTC](https://discuss.elastic.co/t/understanding-bool-must-behavior-intersection/39286/7 "2016-01-15T23:08:49Z")
Hi,
I believe the issue is when using nested documents there is no nested document which has key = color, value= 'Blue, key = Type and value= 'Autoclavable'. What you have is two nested documents one with ( key = color and value= 'Blue') and a second with (key = Type and value= 'Autoclavable'). So this is why the search fails. See this example:
[https://www.elastic.co/guide/en/elasticsearch/guide/current/nested-objects.html](https://www.elastic.co/guide/en/elasticsearch/guide/current/nested-objects.html)
---
### Author:  [@frankd](https://discuss.elastic.co/u/frankd)
#### Post date: [January 15, 2016, 11:15pm UTC](https://discuss.elastic.co/t/understanding-bool-must-behavior-intersection/39286/8 "2016-01-15T23:15:34Z")
That's my problem, thank you.
I guess I'll have to come up with a different index/mapping or look into dynamic mappings.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 5, 2017, 11:23pm UTC](https://discuss.elastic.co/t/understanding-bool-must-behavior-intersection/39286/9 "2017-07-05T23:23:57Z")