[SERVER-48552] Attempt to synchronize ghost timestamps Created: 02/Jun/20 Updated: 09/Jul/20 Resolved: 09/Jul/20 |
|
| Status: | Closed |
| Project: | Core Server |
| Component/s: | Storage |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Improvement | Priority: | Major - P3 |
| Reporter: | Daniel Gottlieb (Inactive) | Assignee: | Eric Milkie |
| Resolution: | Incomplete | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Sprint: | Execution Team 2020-06-15, Execution Team 2020-07-13 |
| Participants: |
| Description |
|
The goal here is to allow for ghost timestamps in spirit, but better control the timestamp used to avoid out-of-order update chains (e.g: 10->20->100->40). When a ghost timestamp is required instead of looking at the logical clock, attempt to perform:
Claims that need to be verified:
|
| Comments |
| Comment by Eric Milkie [ 09/Jul/20 ] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
For now this work seems to be unnecessary, as the underlying WiredTiger storage engine has been modified to support the ghost timestamping behavior. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Comment by Eric Milkie [ 01/Jul/20 ] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
This work is blocked waiting to see if WiredTiger can fix durable history to handle out-of-order update chains. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Comment by Eric Milkie [ 03/Jun/20 ] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Sorry, you're right. I'm working on the 4.4 branch in my development for this. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Comment by Louis Williams [ 03/Jun/20 ] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
milkie this is marked "4.5 Required", but we are actively trying to remove ghost timestamps in this release. I think this should be marked as 4.4-only, right? | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Comment by Daniel Gottlieb (Inactive) [ 02/Jun/20 ] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
A patch that should error if an out-of-order update chain is observed on WT tables susceptible to be affected:
|