# Tableau, dremio and mongodb - error: New schema found and recorded. Please reattempt the query. Multiple attempts may be necessary to fully learn the schema

**URL:** <https://community.dremio.com/t/tableau-dremio-and-mongodb-error-new-schema-found-and-recorded-please-reattempt-the-query-multiple-attempts-may-be-necessary-to-fully-learn-the-schema/2207>\
**Category:** Uncategorized\
**Created:** [November 8, 2018, 4:47pm UTC](https://community.dremio.com/t/tableau-dremio-and-mongodb-error-new-schema-found-and-recorded-please-reattempt-the-query-multiple-attempts-may-be-necessary-to-fully-learn-the-schema/2207 "2018-11-08T16:47:44Z")\
**Posts on this page:** 1\
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**Author:** ![tid](https://sea2.discourse-cdn.com/flex020/user_avatar/community.dremio.com/tid/32/5965_2.png) [@tid](https://community.dremio.com/u/tid)\
**Post date:** [November 8, 2018, 7:58pm UTC](https://community.dremio.com/t/tableau-dremio-and-mongodb-error-new-schema-found-and-recorded-please-reattempt-the-query-multiple-attempts-may-be-necessary-to-fully-learn-the-schema/2207/2 "2018-11-08T19:58:47Z")

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Hi, @dbrys

We’re seeing the exact same two problems. For the “date vs timestamp” issue, we also were able to workaround via casting to Timestamp (see here: [MongoDB Filtering Bug? (using Dremio 3.0.0, MongoDB 3.6.8)](https://community.dremio.com/t/mongodb-filtering-bug-using-dremio-3-0-0-mongodb-3-6-8/2157))

The second issue is related to a schema guessing bug when you switch from Preview mode (which I guess you use for testing your queries in Dremio UI) to “real” mode, see here: [Bug Report: Schema Discovery Problem with nested documents (Dremio 3.0.0 and MongoDB 3.6.8)](https://community.dremio.com/t/bug-report-schema-discovery-problem-with-nested-documents-dremio-3-0-0-and-mongodb-3-6-8/2174/2)). Unfortunately, I’m not aware of any workarounds – if you find one, please let me know.

Best, Tim

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