# Datomic Cloud 990-9202

**URL:** <https://forum.datomic.com/t/datomic-cloud-990-9202/2183>\
**Category:** Announcements\
**Created:** [February 27, 2023, 6:39pm UTC](https://forum.datomic.com/t/datomic-cloud-990-9202/2183 "2023-02-27T18:39:02Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![jaret](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.datomic.com/jaret/32/45_2.png) [@jaret](https://forum.datomic.com/u/jaret)\
**Post date:** [February 27, 2023, 6:39pm UTC](https://forum.datomic.com/t/datomic-cloud-990-9202/2183/1 "2023-02-27T18:39:02Z")

</div>

This message covers changes in this release.

- [critical release notices](https://docs.datomic.com/cloud/releases.html#critical-notices)
- [all release notes](https://docs.datomic.com/cloud/changes.html)

## 2023/02/28 990-9202

- Performance: Datomic now uses caffeine instead of guava for the object cache.
- Performance: improved fressian read.
- Feature: io-stats for transactions and queries. See [Io-Stats | Datomic](https://docs.datomic.com/cloud/api/io-stats.html).
- Feature: query-stats. See [Query Stats | Datomic](https://docs.datomic.com/cloud/api/query-stats.html)
- Fix: Attribute names that begin with an underscore can be used for forward lookups in entity and pull. Note that naming attributes with a leading underscore is strongly discouraged because it conflicts with the convention for reverse lookup.
- Fix: critical bug preventing transactions in 9188.
- Fix: pull performance regression introduced in 9188.
- Fix: Exception when using io-stats in nested contexts, you should no longer see

`"No implementation of method: :-merge-stats of protocol".`

- Upgraded AWS libraries to 1.12.358.