session: fix panic when storing outdated plans from plan cache (#19296) #20246
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Signed-off-by: ti-srebot <ti-srebot@pingcap.com>
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cherry-pick #19296 to release-4.0
What problem does this PR solve?
Issue Number: close #19192
Problem Summary:
Panic instead of error for queries when plan cache is enabled.
What is changed and how it works?
What's Changed:
Reset
session.currentPlanto nil after storing it intoProcessInfo.How it Works:
The root cause of the panic is that, if a query raises error before storing its plan into
session.currentPlan, e.g, error happens in optimizer, then thesession.currentPlanis not updated, i.e, it is the plan for the former query, so after returned todispatch->SetProcessInfo, the plan is accessed again, while the params have already gone, so panic happens.Reset
session.currentPlanto nil after storing it intoProcessInfo, then for the next query, even if it fails to updatesession.currentPlan, there is no risk to access an outdated plan then.Related changes
Check List
Tests
Side effects
N/A
Release note