# Were indexes always included in sqlt\_data\_\* tables?

**URL:** <https://forum.inductiveautomation.com/t/were-indexes-always-included-in-sqlt-data-tables/108985>\
**Category:** Ignition\
**Created:** [July 28, 2025, 12:41am UTC](https://forum.inductiveautomation.com/t/were-indexes-always-included-in-sqlt-data-tables/108985 "2025-07-28T00:41:10Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![nminchin](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/nminchin/32/6911_2.png) [@nminchin](https://forum.inductiveautomation.com/u/nminchin)\
**Post date:** [July 28, 2025, 12:41am UTC](https://forum.inductiveautomation.com/t/were-indexes-always-included-in-sqlt-data-tables/108985/1 "2025-07-28T00:41:10Z")

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I'm looking back at history data tables and I noticed that some older tables (e.g. from before Nov 2023) were querying in 50s instead of \<1s, and found that there was no clustered index on the tagid and t\_stamp fields like there are in later tables. I note this note in the user manual, but there's no mention of when it was added. Was it something that was changed? or did these old tables just get corrupted or something? (these tables were copied to an AWS archive database by the end users's IT, so I have no control or knowledge of what they did)  
Note: the system has been upgraded numerous times over the years so I'm not sure if there was a version upgrade in nov 2023

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/f/6/f604e89ba7168f075a5ef4cf371241418577b1b5.png)

> **[Ignition Database Table Reference | Ignition User Manual](https://www.docs.inductiveautomation.com/docs/8.1/appendix/reference-pages/ignition-database-table-reference#sqlt_data_x_x)**
>
> Ignition has a lot of systems built-in that will query the database automatically without requiring you to build a query. These systems automatically create the necessary tables in the database, insert the relevant data, and even query it back out...

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**Author:** ![lrose](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/lrose/32/62724_2.png) [@lrose](https://forum.inductiveautomation.com/u/lrose)\
**Post date:** [July 28, 2025, 3:46am UTC](https://forum.inductiveautomation.com/t/were-indexes-always-included-in-sqlt-data-tables/108985/2 "2025-07-28T03:46:38Z")

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IIRC, indexes were not always included. I remember seeing somewhere on the forums where it was suggested that the end user needed to add indexes to improve performance.

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**Author:** ![nminchin](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/nminchin/32/6911_2.png) [@nminchin](https://forum.inductiveautomation.com/u/nminchin)\
**Post date:** [July 28, 2025, 4:21am UTC](https://forum.inductiveautomation.com/t/were-indexes-always-included-in-sqlt-data-tables/108985/3 "2025-07-28T04:21:00Z")

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> [@lrose](#):
>
> suggested that the end user needed to add indexes to improve performance

I don't know if I ever did this, but definitely the data tables for 2024 and 2025 all have them and I certainly haven't added them myself. That's why I presumed it was maybe changed in a version. It seems a bit crazy that the tables _wouldn't_ have indexes though... if you have 700,000,000 records it's kind of a necessity! (and not something an integrator should need to add)

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**Author:** ![lrose](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/lrose/32/62724_2.png) [@lrose](https://forum.inductiveautomation.com/u/lrose)\
**Post date:** [July 28, 2025, 4:42am UTC](https://forum.inductiveautomation.com/t/were-indexes-always-included-in-sqlt-data-tables/108985/4 "2025-07-28T04:42:34Z")

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Well, here is a post where I was clearly positive that they were not there by default in 7.9.

> [@Tag Historian/SQL Crashing](https://forum.inductiveautomation.com/t/tag-historian-sql-crashing/84302/13):
>
> The performance issues come in if no indexes have been added to the tables (they aren't there by default in 7.9) and so the database engine will have to trudge through all of that data to gather the information being requested, and that can kill a server that doesn't have enough memory available