# Classpath transaction function with in-memory database possible?

**URL:** <https://forum.datomic.com/t/classpath-transaction-function-with-in-memory-database-possible/679>\
**Category:** Datomic Pro\
**Created:** [October 29, 2018, 12:29pm UTC](https://forum.datomic.com/t/classpath-transaction-function-with-in-memory-database-possible/679 "2018-10-29T12:29:53Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![marcgrue](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.datomic.com/marcgrue/32/170_2.png) [@marcgrue](https://forum.datomic.com/u/marcgrue)\
**Post date:** [October 29, 2018, 12:29pm UTC](https://forum.datomic.com/t/classpath-transaction-function-with-in-memory-database-possible/679/1 "2018-10-29T12:29:53Z")

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I can use a classpath function in a Peer query when using an in-memory database. The Peer picks nicely up on that.

But without a separate running transactor to add a class path to where my class path transaction functions live, it seems that I can’t add such to have it available in transactions when using an in-memory database. Is that correctly understood? (I want to add a Scala function that is compiled to JVM code. Adding the Scala code as a text string itself is not an option).

Is my only option to run any class path transaction function dependent test only with durable setups? (free/starter/pro)

Thanks for any help,  
/Marc

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**Author:** ![stu](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.datomic.com/stu/32/11_2.png) [@stu](https://forum.datomic.com/u/stu)\
**Post date:** [November 7, 2018, 12:00pm UTC](https://forum.datomic.com/t/classpath-transaction-function-with-in-memory-database-possible/679/2 "2018-11-07T12:00:33Z")

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Hi Marc,

I don’t understand the question. It is your classpath, you can add anything you like. In-memory database does not use a transactor.

Cheers,  
Stu

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<div class="post-metadata">

**Author:** ![marcgrue](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.datomic.com/marcgrue/32/170_2.png) [@marcgrue](https://forum.datomic.com/u/marcgrue)\
**Post date:** [November 7, 2018, 1:05pm UTC](https://forum.datomic.com/t/classpath-transaction-function-with-in-memory-database-possible/679/3 "2018-11-07T13:05:54Z")

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Hi Stu,

Sorry I was unclear and thanks for the clarification!

I was maybe hoping for some magic in the in-memory database using tx functions somehow. But of course that doesn’t make sense without having a running transactor, duh.

It seems that setting the classpath variable DATOMIC\_EXT\_CLASSPATH with the free version has no effect/is not supported. Is this correct? If so, I hope you’re planning to make it available in the free version too at some point.

Thanks,  
Marc