ElasticSearch 6.8 doesn't order by exact matches first - elasticsearch

Question

I've been searching for this kind of issue for some days and I didn't make it work. I followed steps like this and this but no success.
So basically, I have the following data on ElasticSearch:
{ title: "Black Dust" },
{ title: "Dust In The Wind" },
{ title: "Gold Dust Woman" },
{ title: "Another One Bites The Dust" }
and the problem is that I want to search by "Dust" word and I want the results be ordered like:
{ title: "Dust In The Wind" },
{ title: "Black Dust" },
{ title: "Gold Dust Woman" },
{ title: "Another One Bites The Dust" }
where "Dust" must appear at the top of the result instead.
Posting the mappings and query would be better than continue explaining the issue itself.
settings: {
analysis: {
normalizer: {
lowercase: {
type: 'custom',
filter: ['lowercase']
}
}
}
},
mappings: {
_doc: {
properties: {
title: {
type: 'text',
analyzer: 'standard',
fields: {
raw: {
type: 'keyword',
normalizer: 'lowercase'
},
fuzzy: {
type: 'text',
},
},
}
}
}
}
and my query is:
"query": {
"bool": {
"must": {
"query_string": {
"fields": [
"title"
],
"default_operator": "AND",
"query": "dust"
}
},
"should": {
"prefix": {
"title.raw": "dust"
}
}
}
}
Can anyone please help me in this?
Thank you!
SOLUTION!
I figured it out and I solved by performing the following query:
"query": {
"bool": {
"must": {
"bool": {
"should": [
{
"prefix": {
"title.raw": {
"value": "dust",
"boost": 1000000
}
}
},
{
"match": {
"title": {
"query": "dust",
"boost": 50000
}
}
},
{
"match": {
"title": {
"query": "dust",
"boost": 10,
"fuzziness": 1
}
}
}
]
}
}
}
}
However, while writing tests, I found a little issue.
So, I'm generating a random uuid and adding to database the following:
{ title: `${uuid} A` }
{ title: `${uuid} W` }
{ title: `${uuid} Z` }
{ title: `A ${uuid}` }
{ title: `z ${uuid}` }
{ title: `Z ${uuid}` }
When I perform the query above looking for the uuid, I get:
uuid Z
uuid A
uuid W
Z uuid
I achieved my first goal that was having the uuid on first position, but why Z is before A? (first and second result)

Answer 1

When everything else fails you can use a trivial substring position sort like so:
{
"query": {
"bool": {
"must": {
...
},
"should": {
...
}
}
},
"sort": [
{
"_script": {
"script": "return doc['title.raw'].value.indexOf('dust')",
"type": "number",
"order": "asc" <--
}
}
]
}
I've set the order to asc because the lower the substring index, the higher the 'score'.
EDIT
We've gotta account for index == -1 so replace the script above with:
"script": "def pos = doc['title.raw'].value.indexOf('dust'); return pos == -1 ? Integer.MAX_VALUE : pos"