Rel Notes 0.10.0 by rasika-chivate · Pull Request #72 · percona/pcsm-docs

rasika-chivate · 2026-09-08T15:52:47Z

Create release notes for PCSM 0.10.0. Update the config files.
Added a limitation about Replica set to sharded cluster migrations: https://perconacorp.slack.com/archives/C06NXH891B6/p1787999278614659

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🟡 Changes recommended

Several documentation links are missing or contradictory, and the release notes contain malformed links and duplicated text.

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Pull request overview

Adds PCSM 0.10.0 release documentation and updates site configuration.

Changes:

Documents 0.10.0 features, fixes, and upgrade requirements.
Adds release navigation, index, version, and date metadata.
Documents replica-set-to-sharded-cluster limitations.

File summaries

File	Description
`variables.yml`	Updates release metadata.
`mkdocs-base.yml`	Adds 0.10.0 navigation.
`docs/release-notes/0.10.0.md`	Adds release notes and changelog.
`docs/release-notes.md`	Adds the release index entry.
`docs/limitations.md`	Adds a sharded-target limitation.

Review details

Files reviewed: 5/5 changed files
Comments generated: 6
Review effort level: Balanced

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Copilot · 2026-09-15T11:13:02Z

+
+    PCSM does not replay source chunk boundaries for hashed shard keys. In this case, it keeps the chunk layout created by MongoDB when the collection is sharded on the target.
+
+To dive deeper into this topic, check out our [documentation](https://docs.percona.com/percona-clustersync-for-mongodb/sharding.html#chunk-distribution).


Updated in f85993b.

Will be fixed in the other PR.

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Co-authored-by: rasika-chivate <95711051+rasika-chivate@users.noreply.github.com>

chupe · 2026-09-16T00:06:51Z

+
+* [PCSM-93](https://perconadev.atlassian.net/browse/PCSM-93): Added active-standby high availability for the replication phase. Multiple PCSM instances coordinate through a lease on the target cluster, and a standby is promoted automatically when the active instance becomes unavailable.
+* [PCSM-241](https://perconadev.atlassian.net/browse/PCSM-241): Improved how PCSM captures the clone start timestamp. PCSM now uses `appendOplogNote` to establish a precise replication starting point after earlier in-flight writes are durable.
+* [PCSM-281](https://perconadev.atlassian.net/browse/PCSM-281): Updated the Go version used to build PCSM from 1.25 to 1.26.


PCSM-374 has since updated the build compiler to Go 1.27.1 in PR #268.

chupe · 2026-09-16T00:09:18Z

+| RHEL 10 | — | x86_64, ARM64 |
+| Rocky Linux 10 | RHEL 10 | x86_64, ARM64 |
+| AlmaLinux 10 | RHEL 10 | x86_64, ARM64 |
+| Oracle Linux 10 ([Red Hat Compatible Kernel (RHCK) :octicons-link-external-16:](https://docs.oracle.com/en/operating-systems/oracle-linux/8/boot/boot-about_linux_kernels.html){:target="_blank"} only) | RHEL 10 | x86_64, ARM64 |


@vorsel can you confirm the supported architectures here? Oracle's release notes say ARM64 ships with UEK only so listing ARM64 alongside “RHCK only” looks contradictory.

@chupe
We can remove RHCK mention here since PCSM is a GO binary, and it is not tied to the kernel used on the installation. Moreover, the link points to the ol8 docs and looks like some outdated artifact.

chupe · 2026-09-16T00:10:37Z

+* [PCSM-281](https://perconadev.atlassian.net/browse/PCSM-281): Updated the Go version used to build PCSM from 1.25 to 1.26.
+* [PCSM-283](https://perconadev.atlassian.net/browse/PCSM-283): Improved migrations from a sharded source cluster to a replica set target. PCSM now detects the target topology and skips sharding operations that a replica set does not support.
+* [PCSM-312](https://perconadev.atlassian.net/browse/PCSM-312): Added support for configuring the MongoDB connection pool size using `maxPoolSize` in the source and target connection strings.
+* [PCSM-322](https://perconadev.atlassian.net/browse/PCSM-322): Improved index handling during finalization. If an index is not created successfully on the target, PCSM now checks whether the index still exists on the source before trying again. This avoids unnecessary attempts to recreate indexes that are no longer present on the source.


This describes failed target index creation however those indexes are explicitly excluded from the source checks. They are retried using their stored specification.
We could describe this as improved handling of incomplete or inconsistent source indexes during finalization instead.

chupe · 2026-09-16T00:12:50Z

+* When both the source and target are sharded clusters, {{pcsm.short}} does not continuously replicate sharding metadata. For ranged shard keys, PCSM uses the source chunk boundaries to initialize the target during the initial sync. Subsequent chunk migrations, splits, and merges aren't reproduced on the target.
+* The primary shard assignment is not preserved. The target cluster can use a different primary shard.
+* Zone configuration is not replicated. See [Zones for sharded data :octicons-link-external-16:](https://www.mongodb.com/docs/manual/core/zone-sharding/).
+* PCSM does not replicate `reshardCollection`, `unshardCollection`, or `refineCollectionShardKey` operations. Changes to sharding metadata made by these operations are not reproduced on the target.


We need to retain the failure warning here. These cause PCSM to go into failure state explicitly. We should be explicit not to perform these operations on collections included in an active synchronization.

Co-authored-by: Adnan <chupe@chupe.ba>

radoslawszulgo · 2026-09-17T08:34:12Z

+
+PCSM 0.10.0 adds packages for new platforms, including RHEL 10 and its derivatives, and Debian 13.
+
+| **Platform** | **Derivative of** | **Architecture** |


I'd remove that column "Derivative of" -> doesn't makes sense for Debian, and doesn't provide the value here.

chupe · 2026-09-17T14:23:27Z

#67, #70, #71 and #72 all touch the sharding.md and limitations.md and in many cases will cause merge conflicts once you start meging.

They carry different claims about topology support, pre-split behaviour and movePrimary. It's anyone's guess how these will be resolved in the end even after we've all invested substantial amount of time reviewing the PRs individually.

We need a better way to handle this...

rasika-chivate · 2026-09-17T14:45:01Z

#67, #70, #71 and #72 all touch the sharding.md and limitations.md and in many cases will cause merge conflicts once you start meging.

They carry different claims about topology support, pre-split behaviour and movePrimary. It's anyone's guess how these will be resolved in the end even after we've all invested substantial amount of time reviewing the PRs individually.

We need a better way to handle this...

I agree, but this is one of a kind. The best way is to create a single PR for the release, as I did previously, to avoid such issues.

Rel Notes 0.10.0

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added new features

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updated config files

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Rel notes for PCSM 0.10.0 and added limitation

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Align sharding chunk distribution docs with pre-splitting behavior

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Update 0.10.0.md

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removed RHCK mention

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chupe mentioned this pull request Sep 17, 2026

PCSM-203 Implement copy of chunk distribution from source #71

Open


		PCSM does not replay source chunk boundaries for hashed shard keys. In this case, it keeps the chunk layout created by MongoDB when the collection is sharded on the target.

		To dive deeper into this topic, check out our [documentation](https://docs.percona.com/percona-clustersync-for-mongodb/sharding.html#chunk-distribution).


		PCSM 0.10.0 adds packages for new platforms, including RHEL 10 and its derivatives, and Debian 13.

		\| Platform \| Derivative of \| Architecture \|

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chupe commented Sep 17, 2026

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rasika-chivate commented Sep 8, 2026 •

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