# Exact match using sentinel token technique (elasticsearch 7.x)
**URL:** https://discuss.elastic.co/t/exact-match-using-sentinel-token-technique-elasticsearch-7-x/369460
**Category:** Elastic Search
**Tags:** painless, elastic-app-search
**Created:** [October 25, 2024, 10:05pm UTC](https://discuss.elastic.co/t/exact-match-using-sentinel-token-technique-elasticsearch-7-x/369460 "2024-10-25T22:05:27Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@stonebanks](https://discuss.elastic.co/u/stonebanks)
#### Post date: [October 25, 2024, 10:05pm UTC](https://discuss.elastic.co/t/exact-match-using-sentinel-token-technique-elasticsearch-7-x/369460/1 "2024-10-25T22:05:27Z")
Hello,
I was reading the Relevant Search book and particularly the sentinel token technique, also described [here](https://discuss.elastic.co/t/exact-match-on-fields-of-type-text-beginning-and-end-anchored/238435/2).
Following the book recipe, the easiest way I could achieve an exact match is by creating a new field in my document so that:
```json
{
"name": "big blue rental car",
"nameWithSentinels": "sentinel_begin big blue rental car sentinel_end"
}
```
and use a `match_phrase` query against the `nameWithSentinels` field with `sentinel_begin sentinel_end` as a value.
However, I do wonder if there's a way a can achieve this without having to create the `nameWithSentinels` field but leveraging the creation of token filters.
I'm thinking of creating a filters that given the following tokens `["big", "blue", "rental", "car"]` would be capable of returning `["sentinel_begin", "big", "blue", "rental", "car", "sentinel_end"]` or `["sentinel_begin big", "blue", "rental", "car sentinel_end"]`(I believe the same `match_phrase` query presented above would still work )
So far my settings looks like this :
```json
{
"idx_0001": {
"settings": {
// stuff removed for brevety
"analysis": {
"filter": {
"sentinel_border_condition_end": {
"filter": [
"sentinel_border_end"
],
"type": "condition",
"script": {
"source": "token.getPosition() === [NO IDEA HOW I CAN GET THE NUMBER OF TOKENS]"
}
},
"sentinel_border_begin": {
"pattern": "^",
"type": "pattern_replace",
"replacement": "SENTINEL_BEGIN"
},
{
"sentinel_border_end": {
"pattern": "$",
"type": "pattern_replace",
"replacement": "SENTINEL_END"
},
"sentinel_border_condition_begin": {
"filter": [
"sentinel_border_begin"
],
"type": "condition",
"script": {
"source": "token.getPosition() === 0"
}
}
},
"analyzer": {
"my-analyzer": {
"filter": [
"sentinel_border_condition_begin",
"sentinel_border_condition_end",
"lowercase",
"stop"
],
"type": "custom",
"tokenizer": "standard"
}
}
}
}
}
}
```
But as you can see I'm not sure of what would be the painless sciript for the `sentinel_border_condition_end` token filter.
Last resort would be creating a plugin but the documentation about token filters plugin is not large from what I can see.
Thank you in advance,
A.
---
### Author:  [@stonebanks](https://discuss.elastic.co/u/stonebanks)
#### Post date: [October 26, 2024, 2:35pm UTC](https://discuss.elastic.co/t/exact-match-using-sentinel-token-technique-elasticsearch-7-x/369460/2 "2024-10-26T14:35:18Z")
I just realized I can achieve what I need using an ingest pipeline actually
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [November 23, 2024, 2:35pm UTC](https://discuss.elastic.co/t/exact-match-using-sentinel-token-technique-elasticsearch-7-x/369460/3 "2024-11-23T14:35:59Z")
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