[RELEASE] ScyllaDB Rust Driver 0.15.0

Release Notes
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The ScyllaDB team is pleased to announce ScyllaDB Rust Driver 0.15.0,
an asynchronous CQL driver for Rust, optimized for Scylla, but also compatible with Apache Cassandra!

Some interesting statistics:

  • over 2.516k downloads on crates!
  • over 583 GitHub stars!

Changes

Beginning with this release, instead of putting all API-breaking changes into one group, now they are in the proper categories, but labeled as :warning: [API-breaking].

Main changes:

New deserialization API

The main change in this release is the deserialization API refactor. Its primary goal was to reduce overhead caused by all rows being eagerly deserialized to type-erased CqlValue type, only then being converted to end user types.
Old traits and structs (FromCqlVal, FromRow, QueryResult - renamed to LegacyQueryResult, RowIterator - renamed to LegacyRowIterator, TypedRowIterator - renamed to LegacyTypedRowIterator) are replaced by new ones (DeserializeValue, DeserializeRow, new QueryResult, QueryPager, TypedRowStream). There are wrappers and helper implementations provided, designed to aid in gradually migrating to new API - see the migration guide in the book for more information. Old traits and structs will be removed in one of future versions.

New serialization API has a benefit of increased efficiency - now, rows are deserialized straight to the end user type, without any copying and allocations on the way.
Another feature is the ability to deserialize rows to borrowed types (e.g. &str or &[u8]).
And the result metadata is now deserialized in the borrowed form, saving even more allocations.

The refactor included:

  • :warning: [API-breaking] Parametrized Deserialize{Value,Row} with two lifetimes: 'frame and 'metadata separately (#1101).
  • :warning: [API-breaking] The deserialization refactor was finished (#1088, #1107, #1109, #1093, #1057, #1120, #1118, #1122, #1121).
  • :warning: [API-breaking] Unified macro attributes’ syntax and semantics between serialization and deserialization derive macros (#1119).

Other changes by category:

New features / enhancements:

  • :warning: [API-breaking] Made ResultMetadata lifetime-generic, which paved a path to deserializing metadata in a borrowed way as an optimisation to save allocations (#1082).
  • Exported serialization migration macros that accidentally hadn’t been exported before (#1089).
  • Exposed public getters to type-erased errors (#1087).
  • Trace message is now issued upon successful keepalive (#1092).
  • Added SerializeRow impl for Box<T: SerializeRow> (#1105).
  • Exposed public getters for execution profile configuration (#1104).
  • Allowed public access to the profile associated with an execution profile handle (#1112).

Bug fixes:

  • :warning: [API-breaking] Fixed driver’s logic that bases on error variants returned from query execution (#1075).
  • Fixed possible panic in speculative execution (#1086)
  • :warning: [API-breaking] Disallowed deserializing Counter type to plain i64 for type safety (#1106).
  • Fixed logic about ignoring particular error kinds if speculative execution failed (#1124).

API cleanups / better types:

  • :warning: [API-breaking] Some of our error types were restructured to be more strongly typed (instead of just containing a string) and better reflect the conditions that they appear in. This work will be continued in 0.16. (#1067, #1074, #1054, #1080, #1080, #1117).
  • Removed wildcard re-exports of the serialization framework’s entities (#1090).
  • :warning: [API-breaking] Made RetryPolicy stored behind Arc instead of Box (#1103).

Internal API cleanups/refactors:

  • Removed paging state parameter from unpaged raw Connection’s API (#1084).
  • :warning: [API-breaking] Fixed unnameable types in our codebase (by making them exposed, unexposing them or deleting them at all) and enabled the unnameable_types clippy lint to prevent having such situation in the future (#1094).
  • Tiny optimizations and code refactors (#1108).

Documentation:

CI / developer tool improvements:

  • clippy was appeased again (#1072, #1077, #1095).
  • Pinned Rust version in book.yml CI workflow (#1096).

Others:

  • Rewritten RELEASE.md, so that it now contains up-to-date guide about maintaining and releasing the driver (#1076).
  • Bumped MSRV to 1.70 (#1098).
  • Added an example showing Counter UPDATE (#1100).

Congrats to all contributors and thanks everyone for using our driver!

The source code of the driver can be found here:

The official crates.io registry entry is here:

Thank you for your attention, please do not hesitate to contact us if you have any questions, issues, feature requests, or are simply interested in our driver!

Contributors since the last release:

commits author
154 Mikołaj Uzarski
89 Wojciech Przytuła
45 Karol Baryła
26 Piotr Dulikowski
3 David Garcia
1 Daniel Boll
1 Alex Pozhylenkov