[SERVER-40881] Jumbo chunk not marked as jumbo Created: 29/Apr/19 Updated: 22/Aug/19 Resolved: 11/Jul/19 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | None |
| Affects Version/s: | 3.4.2 |
| Fix Version/s: | None |
| Type: | Question | Priority: | Major - P3 |
| Reporter: | Björn Kautler | Assignee: | Eric Sedor |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
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| Description |
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I'm new to MongoDB and took some courses at the MongoDB University. |
| Comments |
| Comment by Eric Sedor [ 11/Jul/19 ] | |||||
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Hi, We haven’t heard back from you for some time, so I’m going to mark this ticket as resolved. If this is still an issue for you, please provide additional information and we will reopen the ticket. Thank you! | |||||
| Comment by Eric Sedor [ 24/Jun/19 ] | |||||
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Hi, I wanted to see if you got my last message and had a chance to check the chunks collection in the config database for the chunks the logs reported as becoming jumbo. Thanks, | |||||
| Comment by Eric Sedor [ 30/May/19 ] | |||||
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Hi vampire; one way of looking at what kevin.pulo is saying is that it is the Balancer which decides when a chunk is jumbo. And it looks like from the logs that it does so. shard01 reports:
and the balancer reports:
If this chunk is not seen as jumbo when you inspect the chunk document in the config server, then we would consider this problem as a duplicate of Gratefully, | |||||
| Comment by Björn Kautler [ 25/May/19 ] | |||||
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Sorry for the late answer, I somehow didn't see there was an answer and missed checking manually. eric.sedor I attached the requested logfile unmodified. kevin.pulo
This means that chunks will never be marked as jumbo during any of:
I am aware that manual migrations or splits do not cause marking as jumbo. Here some examples: https://docs.mongodb.com/manual/core/sharding-data-partitioning/#jumbo-chunks says "In some cases, chunks can grow beyond the specified chunk size but cannot undergo a split. The most common scenario is when a chunk represents a single shard key value. Since the chunk cannot split, it continues to grow beyond the chunk size, becoming a jumbo chunk." The video of M312 MongoDB University Course in Chapter 4 labeled "Lecture: Sharding Issues" also suggests that the chunk gets marked jumbo if shard size gets exceeded. https://docs.mongodb.com/manual/core/sharding-data-partitioning/index.html says "Automatic splitting only occurs during inserts or updates." and "Inserts and updates may trigger splits." and later on that the balancer just just moves the chunks around that were split during insert or update to regain an even distribution amongst the shards. kevin.pulo No, not yet, as all material I've seen so far suggested to me that it should work like I tried it. :-/ | |||||
| Comment by Kevin Pulo [ 01/May/19 ] | |||||
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Chunks are only marked as jumbo by the balancer in certain limited circumstances:
This means that chunks will never be marked as jumbo during any of:
Have you tried arranged things such that the balancer will attempt to migrate the chunk in question? And have you ensured that prior to this, the chunk contains a large number (more than 250,000, or possibly even more than this) of small documents with identical shard key value? | |||||
| Comment by Eric Sedor [ 29/Apr/19 ] | |||||
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One possibility is that you are encountering |