# Why are children of the and-filter cached?
**URL:** https://discuss.elastic.co/t/why-are-children-of-the-and-filter-cached/19645
**Category:** Elasticsearch
**Created:** [September 5, 2014, 1:46pm UTC](https://discuss.elastic.co/t/why-are-children-of-the-and-filter-cached/19645 "2014-09-05T13:46:58Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Andre\_Hansel](https://discuss.elastic.co/u/Andre_Hansel)
#### Post date: [September 5, 2014, 1:46pm UTC](https://discuss.elastic.co/t/why-are-children-of-the-and-filter-cached/19645/1 "2014-09-05T13:46:58Z")
According to
> **[All About Elasticsearch Filter BitSets
| Elastic](https://www.elastic.co/blog/all-about-elasticsearch-filter-bitsets)**
>
> WARNING: This article contains outdated information. We no longer recommend taking its advice. When building queries in Elasticsearch, you’ll often find yourself composing sets of filters. Say you nee...
filters inside an and-filter don't use a BitSet but only check the
conditions inside the iterated documents.
When I look at the explanation of
GET megacorp/employee/\_search?explain=1
{
"query": {
"filtered": {
"filter": {
"and": [
{ "term": { "age": "25" } },
{ "term": { "last\_name": "smith" } }
]
}
}
}
}
it says:
"\_explanation": {
"value": 1,
"description": "ConstantScore(+cache(age:[25 TO 25])
+cache(last\_name:smith)), product of:",
"details": [
{ "value": 1, "description": "boost" }, { "value": 1, "description":
"queryNorm" }
]
}
What does that "cache()" actually mean and how is it beneficial to check
conditions in each document?
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---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 6, 2017, 1:04am UTC](https://discuss.elastic.co/t/why-are-children-of-the-and-filter-cached/19645/2 "2017-07-06T01:04:07Z")