-
Type:
Improvement
-
Resolution: Fixed
-
Priority:
Blocker - P1
-
Affects Version/s: None
-
Component/s: None
-
None
-
Query Optimization
-
Fully Compatible
-
None
-
None
-
None
-
None
-
None
-
None
-
None
SERVER-136193 applies the 0-CE fallback in all cases when an index scan has a 0 inCE.
This applies also to sort queries, and queries with an inner $or (under an $and). However, this results in quite a lot of regressions, because MP is not good at estimating such queries:
- In plans with blocking sort CBR costs them, MP exhausts the budget without results and MP tie breaking heuristics pick a worse plan.
- Plans with non-top-level $OR. MP favors the plan with the most productive left branch which is not necessarily the best.
This ticket will limit the 0-CE fallback to not apply in these two cases, because CBR still produces better plans.
- is related to
-
SERVER-136193 Reduce the number of plans that get handed to multi planner when zero CE
-
- Closed
-
-
-
- Needs Scheduling
-
- related to
-
-
- Open
-
-
-
- Backlog
-