# Advanced feature: indexPattern:fieldMapping:lookBack **URL:** \ **Category:** Kibana\ **Created:** [July 9, 2018, 10:37am UTC](https://discuss.elastic.co/t/advanced-feature-indexpatternlookback/139142 "2018-07-09T10:37:13Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![rcowart](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rcowart/32/88091_2.png) [@rcowart](https://discuss.elastic.co/u/rcowart)\ **Post date:** [July 9, 2018, 10:37am UTC](https://discuss.elastic.co/t/advanced-feature-indexpatternlookback/139142/1 "2018-07-09T10:37:13Z")
Reading the description for `indexPattern:fieldMapping:lookBack`: > For index patterns containing timestamps in their names, look for this many recent matching patterns from which to query the field mapping I would expect that when setting up or refreshing an Index Pattern in Kibana, it would only consider the mapping of the last 5 indices. However that is not what is happening. It is definitely looking back at mappings of older indices as well. Unfortunately this setting is not covered in the docs ([Advanced Settings | Kibana Guide [8.11] | Elastic](https://www.elastic.co/guide/en/kibana/current/advanced-options.html)), so I can't confirm how this is supposed to work. Does anyone have any insights on the expected behavior of this setting? ---
**Author:** ![christophilus](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/christophilus/32/42991_2.png) [@christophilus](https://discuss.elastic.co/u/christophilus)\ **Post date:** [July 9, 2018, 2:27pm UTC](https://discuss.elastic.co/t/advanced-feature-indexpatternlookback/139142/2 "2018-07-09T14:27:59Z")
Hi Robert, the default value for this setting is 5, so I think your assumptions are correct. This may be a bug, but it could also be that your indices have incorrectly formatted timestamps in their names. If you think it's a bug, you can log it here: [https://github.com/elastic/kibana/issues](https://github.com/elastic/kibana/issues) Please provide more info, if you do log a bug: - A list of your index names (at least going back as far as the index whose mappings are incorrectly showing up) - Mappings from the old index (that shouldn't be showing up) - Some of the mappings from the more recent indices (that should be showing up) - The version of Kibana you're running Thanks! ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [August 6, 2018, 2:27pm UTC](https://discuss.elastic.co/t/advanced-feature-indexpatternlookback/139142/3 "2018-08-06T14:27:59Z")
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