boosting along with prefix query with all - elasticsearch

Question

I want to be able to prefix query on EACH of search terms found in any field, and I would like to be able to have highlighting. I formulated a query which seems to work. Now, I want to update query so that matches in one of the fields yields a higher score than matches in the other fields.
For example I index the following data (this is just a sample, in my real data there are many more fields than just the two):
PUT /my_index/my_type/abc124
{
"title" : "blah",
"description" : "golf"
}
PUT /my_index/my_type/abc123
{
"title" : "blah golf",
"description" : "course"
}
PUT /my_index/my_type/abc125
{
"title" : "blah golf tee",
"description" : "course"
}
Then I can query as mentioned with a query like:
POST my_index/my_type/_search
{
"query": {
"bool": {
"must": [
{
"prefix": {
"_all" : "gol"
}
},
{
"prefix": {
"_all": "bla"
}
}
]
}
},
"highlight":{
"fields":{
"*":{}
}
}
}
Which produces the result:
{
"took": 11,
"timed_out": false,
"_shards": {
"total": 4,
"successful": 4,
"failed": 0
},
"hits": {
"total": 3,
"max_score": 1.4142135,
"hits": [
{
"_index": "my_index",
"_type": "my_type",
"_id": "abc125",
"_score": 1.4142135,
"_source": {
"title": "blah golf tee",
"description": "course"
},
"highlight": {
"title": [
"<em>blah</em> <em>golf</em> tee"
]
}
},
{
"_index": "my_index",
"_type": "my_type",
"_id": "abc124",
"_score": 1.4142135,
"_source": {
"title": "blah",
"description": "golf"
},
"highlight": {
"description": [
"<em>golf</em>"
],
"title": [
"<em>blah</em>"
]
}
},
{
"_index": "my_index",
"_type": "my_type",
"_id": "abc123",
"_score": 1.4142135,
"_source": {
"title": "blah golf",
"description": "course"
},
"highlight": {
"title": [
"<em>blah</em> <em>golf</em>"
]
}
}
]
}
}
How can I modify the scoring using function_score or other means so that I can score matches on title field higher than other fields? Do I need to change the query to multi-match instead of using _all? Any suggestions would be appreciated.
Regards,
LT

Answer 1

Try adding to your bool query a should section which would give a higher score to the whole query if any of the statements in the should match (and it's not mandatory for those to match for the query to return results).
For example, try this:
POST my_index/my_type/_search
{
"query": {
"bool": {
"must": [
{
"prefix": {
"_all": "gol"
}
},
{
"prefix": {
"_all": "bla"
}
}
],
"should": [
{
"prefix": {
"title": {
"value": "gol",
"boost": 3
}
}
},
{
"prefix": {
"title": {
"value": "bla",
"boost": 3
}
}
}
]
}
},
"highlight": {
"fields": {
"*": {}
}
}
}