# Is it possible to use transform scripts in mappings to alter document \_id? **URL:** \ **Category:** Elasticsearch\ **Created:** [November 29, 2014, 3:20am UTC](https://discuss.elastic.co/t/is-it-possible-to-use-transform-scripts-in-mappings-to-alter-document--id/20984 "2014-11-29T03:20:39Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Reason](https://avatars.discourse-cdn.com/v4/letter/r/e56c9b/32.png) [@Reason](https://discuss.elastic.co/u/Reason)\ **Post date:** [November 29, 2014, 3:20am UTC](https://discuss.elastic.co/t/is-it-possible-to-use-transform-scripts-in-mappings-to-alter-document--id/20984/1 "2014-11-29T03:20:39Z")
The Elasticsearch documentation is always frustratingly silent on the things I seem to need to accomplish to make life easier. Is it possible to use a transform script in a mapping to alter the document \_id? This would be a convenient way to de-dup incoming data I have too little control over if so. After digging around online and not finding much of use, I naively tried this in Elasticsearch 1.4, which alas did nothing: "typename": { "transform": { "script": "ctx.\_source['useAsId'] = ctx.\_source['a'] + ctx.\_source['b']" , "lang": "groovy" }, "\_id" { "path": "useAsId" }, "properties": { "a": { "type": "string" }, "b": { "type": "string" }, "useAsId": { "type": "string" } } } It seems that the ordering of operations isn't what I'd like it to be under the hood; I don't get the \_id I'd want out of this, but rather get the standard auto-assigned \_id value. So is there a way to process an incoming document to alter the \_id value in this sort of way? Or there another more generally accepted route to de-duping? -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/0d2fbf40-619e-4af6-b991-4c4cfa4133c0%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/0d2fbf40-619e-4af6-b991-4c4cfa4133c0%40googlegroups.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![nik9000](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/nik9000/32/44947_2.png) [@nik9000](https://discuss.elastic.co/u/nik9000)\ **Post date:** [November 29, 2014, 4:24am UTC](https://discuss.elastic.co/t/is-it-possible-to-use-transform-scripts-in-mappings-to-alter-document--id/20984/2 "2014-11-29T04:24:12Z")
On Nov 28, 2014 10:20 PM, "Reason" [reason@bazaarvoice.com](mailto:reason@bazaarvoice.com) wrote: > The Elasticsearch documentation is always frustratingly silent on the > things I seem to need to accomplish to make life easier. Sorry you feel that way. If you are willing to fix the documentation those pull requests are typically merged quickly and don't need to be attached to an issue. > Is it possible to use a transform script in a mapping to alter the > document \_id? This would be a convenient way to de-dup incoming data I have > too little control over if so. I wrote the transform script feature and I have no idea. It wasn't for that but that doesn't mean it couldn't work. > After digging around online and not finding much of use, I naively tried > this in Elasticsearch 1.4, which alas did nothing: > > "typename": { > "transform": { > "script": "ctx.\_source['useAsId'] = ctx.\_source['a'] + > ctx.\_source['b']", > "lang": "groovy" > }, > "\_id" { > "path": "useAsId" > }, > "properties": { > "a": { "type": "string" }, > "b": { "type": "string" }, > "useAsId": { "type": "string" } > } > } > > It seems that the ordering of operations isn't what I'd like it to be > under the hood; I don't get the \_id I'd want out of this, but rather get > the standard auto-assigned \_id value. It looks like your proven that transform won't work for this. As I said transform wasn't meant to do this so I implemented it by adding it in the most convenient spot which iirc is right before fields are sent to lucene. Changing the ID would require doing it before the document is routed which means the changes the script makes would have to be serialized for routing and I didn't want to deal with that. Sorry! I image you could implement a transform early pretty easily if you just wanted to change the ID because that wouldn't need special serialization. But then you'd have to wait for the pull request to be reviewed and for the next minor release which is probably not what you want. > So is there a way to process an incoming document to alter the \_id value > in this sort of way? Or there another more generally accepted route to > de-duping? The route I use is id based. You have to construct the ID in the client application though. You can you van totally perform queries in the client before the update to check for dupes but that too is a pain. You could make them perform pretty well with routing I imagine though. Nik > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). > To view this discussion on the web visit > [https://groups.google.com/d/msgid/elasticsearch/0d2fbf40-619e-4af6-b991-4c4cfa4133c0%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/0d2fbf40-619e-4af6-b991-4c4cfa4133c0%40googlegroups.com) > . > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/CAPmjWd3X6zN5AYPPr5-4\_Q6Uxi2xwWqN0vTX7FKFQuFx1ATbTw%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAPmjWd3X6zN5AYPPr5-4_Q6Uxi2xwWqN0vTX7FKFQuFx1ATbTw%40mail.gmail.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**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, 12:47am UTC](https://discuss.elastic.co/t/is-it-possible-to-use-transform-scripts-in-mappings-to-alter-document--id/20984/3 "2017-07-06T00:47:07Z")