chore: release v0.21.0 (#684)

* chore: release v0.20.1

* Improve CHANGELOG.md

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Frank McSherry <fmcsherry@me.com>

Author: github-actions[bot]

Cargo.toml

@@ -22,7 +22,7 @@ edition = "2021"
 rust-version = "1.86"
 
 [workspace.dependencies]
-differential-dataflow = { path = "differential-dataflow", default-features = false, version = "0.20.0" }
+differential-dataflow = { path = "differential-dataflow", default-features = false, version = "0.21.0" }
 timely = { version = "0.28", default-features = false }
 columnar = { version = "0.12", default-features = false }
 #timely = { git = "https://github.com/TimelyDataflow/timely-dataflow" }

differential-dataflow/CHANGELOG.md

@@ -7,6 +7,25 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.21.0](https://github.com/TimelyDataflow/differential-dataflow/compare/differential-dataflow-v0.20.0...differential-dataflow-v0.21.0) - 2026-03-25
+
+### Added
+
+- `Arranged::as_container` convenience method for extracting non-`Vec` containers from arrangements ([#695](https://github.com/TimelyDataflow/differential-dataflow/pull/695))
+- `Columnation` and `Columnar` implementations for the `Present` zero-sized difference type ([#682](https://github.com/TimelyDataflow/differential-dataflow/pull/682))
+
+### Changed
+
+- Update to timely 0.28 and columnar 0.12 ([#698](https://github.com/TimelyDataflow/differential-dataflow/pull/698))
+- Adopt internal iteration for consolidation, merge batching, and trace building, replacing external iteration that leaked internal types through abstractions ([#689](https://github.com/TimelyDataflow/differential-dataflow/pull/689))
+
+### Fixed
+
+- Eliminate a redundant `arrange` in `propagate` and a double scope-import in `scc` ([#692](https://github.com/TimelyDataflow/differential-dataflow/pull/692))
+
+The main theme of this release is internal iteration: consolidation, merging, and trace building now happen behind trait methods rather than exposing container internals outward.
+Dependency updates track timely 0.28 and columnar 0.12.
+
 ## [0.20.0](https://github.com/TimelyDataflow/differential-dataflow/compare/differential-dataflow-v0.19.1...differential-dataflow-v0.20.0) - 2026-03-05
 
 ### Other

differential-dataflow/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 
 name = "differential-dataflow"
-version = "0.20.0"
+version = "0.21.0"
 authors = ["Frank McSherry <fmcsherry@me.com>"]
 
 description = "An incremental data-parallel dataflow platform"

dogsdogsdogs/CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.21.0](https://github.com/TimelyDataflow/differential-dataflow/compare/differential-dogs3-v0.20.0...differential-dogs3-v0.21.0) - 2026-03-25
+
+### Other
+
+- update Cargo.toml dependencies
+
 ## [0.20.0](https://github.com/TimelyDataflow/differential-dataflow/compare/differential-dogs3-v0.19.1...differential-dogs3-v0.20.0) - 2026-03-05
 
 ### Other

dogsdogsdogs/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "differential-dogs3"
-version = "0.20.0"
+version = "0.21.0"
 authors = ["Frank McSherry <fmcsherry@me.com>"]
 license = "MIT"
 edition.workspace = true