# Tag History Partitioning

**URL:** <https://forum.inductiveautomation.com/t/tag-history-partitioning/33186>\
**Category:** Ignition\
**Created:** [March 18, 2020, 12:02am UTC](https://forum.inductiveautomation.com/t/tag-history-partitioning/33186 "2020-03-18T00:02:55Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![diat150](https://avatars.discourse-cdn.com/v4/letter/d/a587f6/32.png) [@diat150](https://forum.inductiveautomation.com/u/diat150)\
**Post date:** [March 18, 2020, 12:02am UTC](https://forum.inductiveautomation.com/t/tag-history-partitioning/33186/1 "2020-03-18T00:02:55Z")

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I have a system that does not have tag history partitioning enabled. I was just wondering what would happen if this was turned on after say a years worth of data was stored. Would it be a seamless transition to using the partitioning where trends that cross the threshold would not break?

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**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\
**Post date:** [March 18, 2020, 3:32pm UTC](https://forum.inductiveautomation.com/t/tag-history-partitioning/33186/2 "2020-03-18T15:32:31Z")

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Yes. The part of the historian that actually performs queries is independent of the mechanism that actually stores into partitions - by design, the only “communication” the two pieces have is the sqlth\_partitions table, which you’ll notice has a start and end timestamp. Once you enable partitioning, each new partition created will just make a new record in that table (along with its actual data partition table). Querying automatically bridges the gaps in those start and end timestamps.