[SERVER-57790] Minimise the impact of FCV upgrade/downgrade between 4.4 and 5.0 with large routing tables Created: 17/Jun/21 Updated: 29/Oct/23 Resolved: 16/Jul/21 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | None |
| Affects Version/s: | 5.0.0-rc2 |
| Fix Version/s: | 5.0.2, 5.1.0-rc0 |
| Type: | Improvement | Priority: | Major - P3 |
| Reporter: | Kaloian Manassiev | Assignee: | Paolo Polato |
| Resolution: | Fixed | Votes: | 1 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Backwards Compatibility: | Fully Compatible | ||||||||
| Backport Requested: |
v5.0
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| Sprint: | Sharding EMEA 2021-07-12, Sharding EMEA 2021-07-26 | ||||||||
| Participants: | |||||||||
| Description |
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The format of the sharding catalog has been changed starting from version 5.0. The change impacts the contents of all entries in the config.databases/collections/chunks/shards system collections and the upgrade/downgrade steps need to update a lot of data. The data updates are synchronised per collection under the chunks lock, which means that for collections with a lot of chunks, chunk migrations can be blocked for a longer time. Since the chunk commit happens during the migration critical section, any shard which attempts to commit a chunk migration at that point in time will block access to the portion of the collection that it holds. In order to mitigate this impact, it is proposed that we do 2 things:
Option (1) can be done later since it needs to remember if the balancer was stopped, but (2) is fairly easy and can be done earlier. |
| Comments |
| Comment by Vivian Ge (Inactive) [ 06/Oct/21 ] |
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Updating the fixversion since branching activities occurred yesterday. This ticket will be in rc0 when it’s been triggered. For more active release information, please keep an eye on #server-release. Thank you! |
| Comment by Githook User [ 26/Jul/21 ] |
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Author: {'name': 'Paolo Polato', 'email': 'paolo.polato@mongodb.com', 'username': 'ppolato'}Message: (cherry picked from commit a3e0e9d2998bd9a1ce0f8f975b364ef614e2d57c) |
| Comment by Githook User [ 26/Jul/21 ] |
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Author: {'name': 'Paolo Polato', 'email': 'paolo.polato@mongodb.com', 'username': 'ppolato'}Message: (cherry picked from commit 804ddfe0dcf1b5f26e1afd83b47cb1ef5df888bd) |
| Comment by Githook User [ 16/Jul/21 ] |
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Author: {'name': 'Paolo Polato', 'email': 'paolo.polato@mongodb.com', 'username': 'ppolato'}Message: |
| Comment by Githook User [ 06/Jul/21 ] |
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Author: {'name': 'Paolo Polato', 'email': 'paolo.polato@mongodb.com', 'username': 'ppolato'}Message: |