# Update api & consistency **URL:** \ **Category:** Elasticsearch\ **Created:** [January 21, 2014, 8:00pm UTC](https://discuss.elastic.co/t/update-api-consistency/15347 "2014-01-21T20:00:26Z")\ **Posts on this page:** 4\ **Page:** 1

**Author:** ![revdev\_2](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/revdev_2/32/1852_2.png) [@revdev\_2](https://discuss.elastic.co/u/revdev_2)\ **Post date:** [January 21, 2014, 8:00pm UTC](https://discuss.elastic.co/t/update-api-consistency/15347/1 "2014-01-21T20:00:26Z")

We have two processes, each running on different machines that operate on an ES cluster. One process indexes a document using write consistency ALL and then makes the document available to the other process right away. The other process performs some other work and then it needs to set a flag in the document to make it searchable - this is done using the Update API. In 90-95% of the cases, this works fine but in some rare instances we are seeing 404s on the /\_update request. Though even rarer (\< 1%), we see a 409 response code. I would've thought that write consistency ALL would make the document available for the update API. Can anyone comment on this use case or why we might be seeing these issues (or if this is a known issue)? We're currently running 0.90.7 in the cluster and have 5 members that are data/master true. -- 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/7de196d8-ee4e-4502-a326-c9831b32673d%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/7de196d8-ee4e-4502-a326-c9831b32673d%40googlegroups.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---

**Author:** ![jprante](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jprante/32/44941_2.png) [@jprante](https://discuss.elastic.co/u/jprante)\ **Post date:** [January 21, 2014, 10:34pm UTC](https://discuss.elastic.co/t/update-api-consistency/15347/2 "2014-01-21T22:34:06Z")

Write consistency = ALL returns to the client after all nodes that hold shards have responded, but that does not necessarily mean they are available for "get" by other clients (update is using get operation to retrieve the document). If you want causality in your data writes and reads, you must use the refresh operation (with all the negative impacts on performance). Jörg -- 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/CAKdsXoG%2BBoKqNJS66OFSFnzE8zuMeq3251iMcusT9ttE8cL6pQ%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAKdsXoG%2BBoKqNJS66OFSFnzE8zuMeq3251iMcusT9ttE8cL6pQ%40mail.gmail.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---

**Author:** ![javanna](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/javanna/32/4698_2.png) [@javanna](https://discuss.elastic.co/u/javanna)\ **Post date:** [January 22, 2014, 10:00am UTC](https://discuss.elastic.co/t/update-api-consistency/15347/3 "2014-01-22T10:00:43Z")

Write consistency in elasticsearch is quite different to what has been described here. You can think of it as a check done before indexing, to make sure that enough copies of the data are available. It doesn't have anything to do with when the response is returned and only affects whether the write operation is accepted or not in the first place. On the other hand, the replication (sync by default) affects when the response is returned: by default after all copies have the document indexed, only after the primary otherwise (async). Using write consistency in the described usecase doesn't make a difference in terms of making the document available for get, used internally by the update API. In fact, the get API works in real-time, as it can retrieve the documents from the transaction log if a refresh has not happened yet in the lucene index. That means that when the index operation returns, using the default sync replication, all copies (primary + replicas) have the document at least in the transaction log, which can be retrieved using the get API, no refresh needed. Interesting that in some cases you got 404, that sounds weird, are you sure the update happens after the previous operation returned? Also, using the update API the document is always retrieved from the primary shard, modified and reindexed there (+ replication afterwards), thus you could potentially set the replication to async without running into problems when it comes to updating the document using the update API. As for the 409, that's a version conflict, meaning that there probably are multiple updates done to the same document, you might want to tweak retry\_on\_conflict to allow for retries when a conflict is found. On Tuesday, January 21, 2014 11:34:06 PM UTC+1, Jörg Prante wrote: > Write consistency = ALL returns to the client after all nodes that hold > shards have responded, but that does not necessarily mean they are > available for "get" by other clients (update is using get operation to > retrieve the document). > > If you want causality in your data writes and reads, you must use the > refresh operation (with all the negative impacts on performance). > > Jörg -- 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/b1f1b863-980f-4bcf-aa50-f92814f8bb71%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/b1f1b863-980f-4bcf-aa50-f92814f8bb71%40googlegroups.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---

**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, 1:55am UTC](https://discuss.elastic.co/t/update-api-consistency/15347/4 "2017-07-06T01:55:25Z")