# Strange date behaviour when indexing content **URL:** \ **Category:** Elasticsearch\ **Created:** [May 9, 2016, 10:03am UTC](https://discuss.elastic.co/t/strange-date-behaviour-when-indexing-content/49535 "2016-05-09T10:03:04Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![vindoq](https://avatars.discourse-cdn.com/v4/letter/v/87869e/32.png) [@vindoq](https://discuss.elastic.co/u/vindoq)\ **Post date:** [May 9, 2016, 10:03am UTC](https://discuss.elastic.co/t/strange-date-behaviour-when-indexing-content/49535/1 "2016-05-09T10:03:04Z")
Hi. I got a project where we insert bunch of data through spark streaming. Everything was fine until a colleague got a strange behaviour I never had. A date is mapped as "yyyy-MM-dd' 'HH:mm:ss", and only on his computer, some (about 1%) of the date, and randoms ones when we delete and replay the same datas, are inserted with the date of the insert instead of the real date. I tried a lots of thing, like adding a duplicate of the fields, and it was fine. So, maybe it's because we made an alias, and the alias contains other index (we use index\_yy\_ww) which have older mapping (I first tried mapping date with "yyyy-MM-dd HH:mm:ss"). But that's weird, and I would like to know why it's happening. Or maybe I get the wrong format? the docs is not really well documented. If I read it correctly, I should use "yyyy'-'MM'-'dd' 'HH':'mm':'ss" but didn't find any example of this online, thus using the one I found most on stackoverflow ("yyyy-MM-dd' 'HH:mm:ss"). Thanks for the help. ---
**Author:** ![vindoq](https://avatars.discourse-cdn.com/v4/letter/v/87869e/32.png) [@vindoq](https://discuss.elastic.co/u/vindoq)\ **Post date:** [May 9, 2016, 1:38pm UTC](https://discuss.elastic.co/t/strange-date-behaviour-when-indexing-content/49535/2 "2016-05-09T13:38:05Z")
Well, doesn't seems linked to elasticsearch after some research. Seems like both format "yyyy'-'MM'-'dd' 'HH':'mm':'ss" and "yyyy-MM-dd' 'HH:mm:ss" are good. Which one should I use and why "yyyy-MM-dd HH:mm:ss" doesn't work? ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 5, 2017, 10:52pm UTC](https://discuss.elastic.co/t/strange-date-behaviour-when-indexing-content/49535/3 "2017-07-05T22:52:59Z")