Painless query very slowly

Elastic Stack Elasticsearch
1

I'm a beginner, when I use painless script to search ,very slowly ,but use date_histogram very quickly.

`POST /productinfo/_search
{
"aggs": {
"groupbyyear":{
"terms": {
"script": {
"lang": "painless",
"source":"doc['mdate'].value.year"
}
}
}

}
}`

the took is 2494

{ "took": 2494, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 23139644, "max_score": 1,

when I use datehist like this, the took only 438,can somebody tell me why,please!

`POST /productinfo/_search
{
"aggs": {
"groupbyyear":{
"date_histogram": {
"field": "mdate",
"interval": "year"
}
}

}
}`

the result:

{ "took": 438, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 23139644, "max_score": 1, "hits": [

like below also slowly........

POST /productinfo/_search { "aggs": { "groupbydep":{ "terms": { "script": { "lang": "painless", "source":"doc['pdep'].value.substring(0,4)" }

2

Because executing a script on every single document (here 23139644 documents) takes a lot of time.

Why not just using the date_histogram aggregation?

3

In our case, the date group only one, most like below, need substring some string fields to aggs,so ,have other idea to excute below search quickly, worry ,please :joy:
"groupbydep":{ "terms": { "script": { "lang": "painless", "source":"doc['pdep'].value.substring(0,4)"

4

I would recommend parsing it out at index time and storing it in a separate field if it is something you want to aggregate efficiently on at scale. That way you do the parsing once per document rather than once per document per query.

5

ok, thanks,I'll try reindex my document.