Elasticsearch & Elasticpress search by math_phrase with & inside query - wordpress

Question

I have problem with my queries when I'm using " or ' - then I expect match_phrase, but I don't know how I can retrieve posts when I'm using match_phrase with &
For example I'm using Something & Something as phrase, and when I'm didn't using ' and " I can see posts with Something & Something but there I'm using multi_match.
Something what I've tried:
{
"from": 0,
"size": 10,
"sort": {
"post_date": {
"order": "desc"
}
},
"query": {
"function_score": {
"query": {
"bool": {
"must": [
{
"match_phrase": {
"query": "Something & Something"
}
}
]
}
},
"exp": {
"post_date_gmt": {
"scale": "270d",
"decay": 0.5,
"offset": "90d"
}
},
"score_mode": "avg",
"boost_mode": "sum"
}
},
"post_filter": {
"bool": {
"must": [
{
"terms": {
"post_type.raw": [
"post"
]
}
},
{
"terms": {
"post_status": [
"publish"
]
}
}
]
}
}
}
But this doesn't return any post, and returning hits total 0. Anyone have any idea, or suggestions, what I'm doing wrong ?

Answer 1

match_phrase is very restrictive and in most of cases is recommended to use it inside a should clause to increase the score instead of a must, because it requires the user to type the value exactly as it is.
Example document
POST test_jakub/_doc
{
"query": "Something & Something",
"post_type": {
"raw": "post"
},
"post_status": "publish",
"post_date_gmt": "2021-01-01T12:10:30Z",
"post_date": "2021-01-01T12:10:30Z"
}
With this document searching for "anotherthing Something & Something" will return no results, that's why is a bad idea to use match_phrase here.
You can take 2 approaches
If you need this kind of tight queries take a look to the slop parameter that adds some flexibility to the match_phrase query allowing omit or transpose words in the phrase
Switch to a regular match query (recommended). In most cases this will work fine, but if you want to do extra score to the phrase matches you can add it as a should clause.
POST test_jakub/_search
{
"from": 0,
"size": 10,
"sort": {
"post_date": {
"order": "desc"
}
},
"query": {
"function_score": {
"query": {
"bool": {
"should": [
{
"match_phrase": {
"query": {
"query": "anotherthing something & something",
"slop": 2
}
}
}
],
"must": [
{
"match": {
"query": "anotherthing something & something"
}
}
]
}
},
"exp": {
"post_date_gmt": {
"scale": "270d",
"decay": 0.5,
"offset": "90d"
}
},
"score_mode": "avg",
"boost_mode": "sum"
}
},
"post_filter": {
"bool": {
"must": [
{
"terms": {
"post_type.raw": [
"post"
]
}
},
{
"terms": {
"post_status": [
"publish"
]
}
}
]
}
}
}
Last advice is to avoid using "query" as field name because leads to confusion and will break Kibana autocomplete on Dev Tools.