[SERVER-20176] Deletes with j:true slower on WT than MMAPv1 Created: 28/Aug/15 Updated: 31/Aug/23 Resolved: 19/Sep/15 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | WiredTiger |
| Affects Version/s: | 3.0.6, 3.1.7 |
| Fix Version/s: | 3.0.7, 3.1.9 |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Andre de Frere | Assignee: | Geert Bosch |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Backwards Compatibility: | Fully Compatible | ||||||||||||||||||||||||||||||||||||
| Operating System: | ALL | ||||||||||||||||||||||||||||||||||||
| Backport Completed: | |||||||||||||||||||||||||||||||||||||
| Sprint: | Quint 9 09/18/15 | ||||||||||||||||||||||||||||||||||||
| Participants: | |||||||||||||||||||||||||||||||||||||
| Description |
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j:true is expectedly slower than not, but WT is much slower than MMAPv1: MMAPv1
WT
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| Comments |
| Comment by Igor Canadi [ 03/Oct/15 ] |
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Cool. This should fix it: https://reviews.facebook.net/D48087 |
| Comment by Geert Bosch [ 02/Oct/15 ] |
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Yes, that's true. We have some cases where we don't really have anything to write, but still need to wait until the last write was durable. So in essence, we'd be doing an empty unit of work without any writes, but we still need to wait for any writes that happened previously to be durable. I think this is unavoidable, as we avoid doing a write if no actual data changes, but the semantics of w:1 require that all previous writes be durable... -Geert |
| Comment by Igor Canadi [ 02/Oct/15 ] |
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Hey Geert, seems like we no longer call goingToAwaitDurable() before waitUntilDurable(). In tests, I see an invariant: Invariant failure _sync src/mongo/db/modules/rocksdb/src/rocks_recovery_unit.cpp 261 Source: https://logkeeper.mongodb.org/build/560ea1af90413021b1b50d3d/test/560ea225be07c4135fb508c0 This is the code for invariant(), it's pretty straight-forward: https://github.com/mongodb-partners/mongo-rocks/blob/master/src/rocks_recovery_unit.cpp#L261 I'll try to debug where this happens, but if you can offer any insights, I'd be very grateful. |
| Comment by Githook User [ 25/Sep/15 ] |
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Author: {u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'}Message: (cherry picked from commit 37b328aeda5696ff21c86b1258708fe5bede3a16) Conflicts: |
| Comment by Githook User [ 24/Sep/15 ] |
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Author: {u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'}Message: |
| Comment by Githook User [ 24/Sep/15 ] |
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Author: {u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'}Message: |
| Comment by Githook User [ 23/Sep/15 ] |
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Author: {u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'}Message: |
| Comment by Githook User [ 23/Sep/15 ] |
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Author: {u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'}Message: |
| Comment by Githook User [ 19/Sep/15 ] |
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Author: {u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'}Message: |