[6.0.x] Reset read count on RelationalDataReader #27852
Merged
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Description
As part of the EF Core 6.0 query perf optimization cycle, RelationalDataReader started to get recycled across executions, but the read count value wasn't properly reset.
Customer impact
When tracking how many reader reads were performed via DataReaderDisposingEventData.ReadCount, users got incorrect values since the count wasn't properly reset across usages of RelationalDataReader. No known workaround.
How found
Customer reported on 6.0.
Regression
Yes, From 5.0.
Testing
Added test.
Risk
Very low risk, one-line fix.
Backports #27845
Fixes #27652