# Highlighting API **URL:** \ **Category:** Elasticsearch\ **Created:** [July 21, 2010, 2:37pm UTC](https://discuss.elastic.co/t/highlighting-api/3134 "2010-07-21T14:37:13Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Lukas\_Vlcek1](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/lukas_vlcek1/32/819_2.png) [@Lukas\_Vlcek1](https://discuss.elastic.co/u/Lukas_Vlcek1)\ **Post date:** [July 21, 2010, 2:37pm UTC](https://discuss.elastic.co/t/highlighting-api/3134/1 "2010-07-21T14:37:13Z")
Hi, how are PRE and POST tags supposed to work in highlighting? Assume I use: pre\_Tags : ["tag1", "tag2"], post\_tags : ["tag1", "tag2"], The documentation[http://www.elasticsearch.com/docs/elasticsearch/rest\_api/search/#Highlighting](http://www.elasticsearch.com/docs/elasticsearch/rest_api/search/#Highlighting)says: There can be a single tag or more, and the “importance” is ordered. What does it mean? I did not find any unit test for that in ES code. Also I think there might be an issue in the code because if I use "styled" schema then all of my highlighted fragments used only the first tag from the internal array: i.e. _So the question is when can I expect the other tags being used? (hlt2, hlt3, ...)_ Two issues to be fixed: 1. the internal STYLED\_PRE\_TAG array contains two entries for hlt2 (copy&paste?). See [http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L53](http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L53) and this issue propagated into doc as well: [http://www.elasticsearch.com/docs/elasticsearch/rest\_api/search/#Highlighting](http://www.elasticsearch.com/docs/elasticsearch/rest_api/search/#Highlighting) 2. the doc [http://www.elasticsearch.com/docs/elasticsearch/rest\_api/search/#Highlighting](http://www.elasticsearch.com/docs/elasticsearch/rest_api/search/#Highlighting) uses "tag\_schema" but the code [http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L90](http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L90) uses "tags\_schema" Which one is correct? (I assume the code is right, thus "tags\_schema") Regards, Lukas ---
**Author:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\ **Post date:** [July 21, 2010, 5:40pm UTC](https://discuss.elastic.co/t/highlighting-api/3134/2 "2010-07-21T17:40:46Z")
On Wed, Jul 21, 2010 at 5:37 PM, Lukáš Vlček [lukas.vlcek@gmail.com](mailto:lukas.vlcek@gmail.com) wrote: > Hi, > > how are PRE and POST tags supposed to work in highlighting? > > Assume I use: > pre\_Tags : ["tag1", "tag2"], > post\_tags : ["tag1", "tag2"], > > The documentation[http://www.elasticsearch.com/docs/elasticsearch/rest\_api/search/#Highlighting](http://www.elasticsearch.com/docs/elasticsearch/rest_api/search/#Highlighting)says: > There can be a single tag or more, and the “importance” is ordered. > > What does it mean? The Lucene vector highlighter tries to "score" a highlighted hit and that score is how important it is. > I did not find any unit test for that in ES code. > Also I think there might be an issue in the code because if I use "styled" > schema then all of my highlighted fragments used only the first tag from the > internal array: i.e. > _So the question is when can I expect the other tags being used? > (hlt2, hlt3, ...)_ _Depends on your text and your search query._ _> Two issues to be fixed: > > 1. the internal STYLED\_PRE\_TAG array contains two entries for hlt2 > (copy&paste?). See > [http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L53](http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L53) > and this issue propagated into doc as well: > [http://www.elasticsearch.com/docs/elasticsearch/rest\_api/search/#Highlighting](http://www.elasticsearch.com/docs/elasticsearch/rest_api/search/#Highlighting)_ _Yea, i fixed it in the code, can you fix the docs?_ _> 1. the doc > [http://www.elasticsearch.com/docs/elasticsearch/rest\_api/search/#Highlighting](http://www.elasticsearch.com/docs/elasticsearch/rest_api/search/#Highlighting) > uses > "tag\_schema" > but the code > [http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L90](http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L90) > uses > "tags\_schema" > > Which one is correct? (I assume the code is right, thus "tags\_schema")_ _The code is always right ;), its tags\_schema, can you fix that in the docs as well?_ _> Regards, > Lukas_ ---
**Author:** ![Lukas\_Vlcek1](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/lukas_vlcek1/32/819_2.png) [@Lukas\_Vlcek1](https://discuss.elastic.co/u/Lukas_Vlcek1)\ **Post date:** [July 21, 2010, 5:55pm UTC](https://discuss.elastic.co/t/highlighting-api/3134/3 "2010-07-21T17:55:33Z")
Fixed the docs. On Wed, Jul 21, 2010 at 7:40 PM, Shay Banon [shay.banon@elasticsearch.com](mailto:shay.banon@elasticsearch.com)wrote: > On Wed, Jul 21, 2010 at 5:37 PM, Lukáš Vlček [lukas.vlcek@gmail.com](mailto:lukas.vlcek@gmail.com)wrote: > > > Hi, > > > > how are PRE and POST tags supposed to work in highlighting? > > > > Assume I use: > > pre\_Tags : ["tag1", "tag2"], > > post\_tags : ["tag1", "tag2"], > > > > The documentation[http://www.elasticsearch.com/docs/elasticsearch/rest\_api/search/#Highlighting](http://www.elasticsearch.com/docs/elasticsearch/rest_api/search/#Highlighting)says: > > There can be a single tag or more, and the “importance” is ordered. > > > > What does it mean? > > The Lucene vector highlighter tries to "score" a highlighted hit and that > score is how important it is. Let's say I have two pre\_tags, then the first one is used if the score is \> 0.5 and the second tag is used if score \< 0.5 ? Something like that? > > I did not find any unit test for that in ES code. > > Also I think there might be an issue in the code because if I use "styled" > > schema then all of my highlighted fragments used only the first tag from the > > internal array: i.e. > > _So the question is when can I expect the other tags being used? > > (hlt2, hlt3, ...)_ > > > > _Depends on your text and your search query._ > > > > _> Two issues to be fixed: > > > > 1. the internal STYLED\_PRE\_TAG array contains two entries for hlt2 > > (copy&paste?). See > > [http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L53](http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L53) > > and this issue propagated into doc as well: > > [http://www.elasticsearch.com/docs/elasticsearch/rest\_api/search/#Highlighting](http://www.elasticsearch.com/docs/elasticsearch/rest_api/search/#Highlighting)_ > > > > _Yea, i fixed it in the code, can you fix the docs?_ > > > > _> 1. the doc > > [http://www.elasticsearch.com/docs/elasticsearch/rest\_api/search/#Highlighting](http://www.elasticsearch.com/docs/elasticsearch/rest_api/search/#Highlighting) > > uses > > "tag\_schema" > > but the code > > [http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L90](http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L90) > > uses > > "tags\_schema" > > > > Which one is correct? (I assume the code is right, thus "tags\_schema")_ > > > > _The code is always right ;), its tags\_schema, can you fix that in the docs > as well?_ > > > > _> Regards, > > Lukas_ ---
**Author:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\ **Post date:** [July 21, 2010, 6:18pm UTC](https://discuss.elastic.co/t/highlighting-api/3134/4 "2010-07-21T18:18:46Z")
On Wed, Jul 21, 2010 at 8:55 PM, Lukáš Vlček [lukas.vlcek@gmail.com](mailto:lukas.vlcek@gmail.com) wrote: > Fixed the docs. thanks! > On Wed, Jul 21, 2010 at 7:40 PM, Shay Banon [shay.banon@elasticsearch.com](mailto:shay.banon@elasticsearch.com)wrote: > > > On Wed, Jul 21, 2010 at 5:37 PM, Lukáš Vlček [lukas.vlcek@gmail.com](mailto:lukas.vlcek@gmail.com)wrote: > > > > > Hi, > > > > > > how are PRE and POST tags supposed to work in highlighting? > > > > > > Assume I use: > > > pre\_Tags : ["tag1", "tag2"], > > > post\_tags : ["tag1", "tag2"], > > > > > > The documentation[http://www.elasticsearch.com/docs/elasticsearch/rest\_api/search/#Highlighting](http://www.elasticsearch.com/docs/elasticsearch/rest_api/search/#Highlighting)says: > > > There can be a single tag or more, and the “importance” is ordered. > > > > > > What does it mean? > > > > The Lucene vector highlighter tries to "score" a highlighted hit and that > > score is how important it is. > > Let's say I have two pre\_tags, then the first one is used if the score is \> > 0.5 and the second tag is used if score \< 0.5 ? > Something like that? yes, though don't confuse it with search hits scoring. > > > I did not find any unit test for that in ES code. > > > Also I think there might be an issue in the code because if I use > > > "styled" schema then all of my highlighted fragments used only the first tag > > > from the internal array: i.e. > > > _So the question is when can I expect the other tags being used? > > > (hlt2, hlt3, ...)_ > > > > > > > > _Depends on your text and your search query._ > > > > > > > > _> Two issues to be fixed: > > > > > > 1. the internal STYLED\_PRE\_TAG array contains two entries for hlt2 > > > (copy&paste?). See > > > [http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L53](http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L53) > > > and this issue propagated into doc as well: > > > [http://www.elasticsearch.com/docs/elasticsearch/rest\_api/search/#Highlighting](http://www.elasticsearch.com/docs/elasticsearch/rest_api/search/#Highlighting)_ > > > > > > > > _Yea, i fixed it in the code, can you fix the docs?_ > > > > > > > > _> 1. the doc > > > [http://www.elasticsearch.com/docs/elasticsearch/rest\_api/search/#Highlighting](http://www.elasticsearch.com/docs/elasticsearch/rest_api/search/#Highlighting) > > > uses > > > "tag\_schema" > > > but the code > > > [http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L90](http://github.com/elasticsearch/elasticsearch/blob/master/modules/elasticsearch/src/main/java/org/elasticsearch/search/highlight/HighlighterParseElement.java#L90) > > > uses > > > "tags\_schema" > > > > > > Which one is correct? (I assume the code is right, thus "tags\_schema")_ > > > > > > > > _The code is always right ;), its tags\_schema, can you fix that in the docs > > as well?_ > > > > > > > > _> Regards, > > > Lukas_ ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 4:21am UTC](https://discuss.elastic.co/t/highlighting-api/3134/5 "2017-07-06T04:21:51Z")