PCSM-148 Sharding support #17
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Pull request overview
This PR adds sharding support to {{pcsm.full_name}} (version 0.7.0) as a technical preview feature. The changes enable replication between sharded MongoDB clusters while maintaining the existing replica set functionality.
Key changes:
- Introduces comprehensive sharding documentation explaining how {{pcsm.short}} connects through
mongosinstances - Updates product documentation to reflect that sharded clusters are now supported (tech preview)
- Restructures workflow documentation to accommodate both replica set and sharded cluster topologies
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| docs/sharding.md | New comprehensive documentation detailing sharding support, prerequisites, connection strings, balancer behavior, and usage instructions |
| docs/limitations.md | Removed "sharded clusters not supported" limitation and added new sharding-specific limitation about chunk distribution |
| docs/intro.md | Restructured workflow documentation with tabs separating replica set and sharded cluster scenarios |
| docs/install/usage.md | Updated references from {{plm}} to {{pcsm}} and clarified workflow steps |
| docs/install/authentication.md | Added sharded cluster connection string examples with mongos configuration |
| docs/deployment.md | Reorganized content with new sections for version requirements, architectures, and deployment types |
Comments suppressed due to low confidence (1)
docs/sharding.md:1
- The link reference points to
sharding.md#limitations, but the sharding.md file does not contain a section with the anchor#limitations. This will result in a broken link. Consider either adding a 'Limitations' section to sharding.md or updating the link to point to the correct section (e.g.,sharding.md#chunk-distribution).
# Sharding support in {{pcsm.full_name}} (Technical Preview)
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Added info about results of not replicated metadata
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| During the replication stage, {{pcsm.short}} copies indexes from the source to the target cluster as follows: | ||
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| * **Unique indexes handling**: Unique indexes are copied as non-unique indexes during replication. This allows {{pcsm.short}} to handle potential duplicate data that may exist during the migration process. |
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If index section was added, then please add also
- TTL indexes
- hidden indexes
Those also are "modified" on finalize
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Just a minor thing. Since in Finalization stage we describe handling of these indexes each with its own point. Maybe we should do the same here instead of bundiling **Unique indexes handling** together.
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Sorry I'm not following. We have "Unique index handling" in the replication stage and "Unique index conversion" in the finalization stage. Then each index type is also described under its dedicated bullet point. What am I missing?
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docs/intro.md
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| 3. **Real-time replication**: After the initial data sync, {{pcsm.short}} monitors changes in the source and replicates them to the target at runtime. You don't have to stop your source deployment—it operates as usual, accepting client requests. {{pcsm.short}} uses [change streams :octicons-link-external-16:](https://www.mongodb.com/docs/manual/changeStreams/) to track the changes to your data and replicate them to the target. | ||
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| 4. **Control replication**: You can `pause` the replication and `resume` it later. When paused, {{pcsm.short}} saves the timestamp when it stops the replication. After you resume {{pcsm.short}}, it copies the changes from the saved timestamp and continues real-time replication. See [Pause the replication](install/usage.md#pause-the-replication) and [Resume the replication](install/usage.md#resume-the-replication) for command details. |
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it copies the changes from the saved timestamp and continues real-time replication.
It will not copy anything after you resume, but rather PCSM starts watching change stream events from the moment the pause happened.
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| * **Index creation during sync**: If an index is created on the source cluster while the clusters are in sync, {{pcsm.short}} automatically creates the same index on the target cluster. | ||
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| * **Failed index creation**: If {{pcsm.short}} cannot create an index during replication, it proceeds with replication and records the failure. The index creation will be retried during the finalization stage. |
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We should add here the same for incomplete indexes. If the index build is in progress, PCSM will record that in the catalog and proceed with clone. In finalization PCSM will try to create them.
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| During the replication stage, {{pcsm.short}} copies indexes from the source to the target cluster as follows: | ||
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| * **Unique indexes handling**: Unique indexes are copied as non-unique indexes during replication. This allows {{pcsm.short}} to handle potential duplicate data that may exist during the migration process. |
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Just a minor thing. Since in Finalization stage we describe handling of these indexes each with its own point. Maybe we should do the same here instead of bundiling **Unique indexes handling** together.
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