Description
Up until 2.5.5, when a user ran explain on a query, it would have the side effect of dropping the query plan cache for that query "shape."
In 2.5.5+ this behavior no longer holds true and the full set of plans which are considered for the query are pulled from the queryPlanCache itself.
The only direct user-triggered way of dropping the cached plan for a query is by using the QueryPlanCache manipulation methods directly.
I'm not sure if this is mentioned anywhere in our documentation or whether this should be documented specifically, but it is a known behavior pre 2.5.5 and this is a backwards breaking change for users who depended on this behavior.
See: SERVER-7468
Attachments
Issue Links
- related to
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SERVER-7468 Don't invalidate query plans when explain is run
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- Closed
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