Optimize SQL based on parameter nullability #18491
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depends on #18035 |
maumar
commented
Oct 21, 2019
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| protected override Expression VisitExtension(Expression extensionExpression) | ||
| { | ||
| if (extensionExpression is SelectExpression selectExpression) |
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temporary workaround, correct fix tracked here: #18492
smitpatel
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Oct 22, 2019
src/EFCore.Relational/Query/Internal/SqlExpressionOptimizingExpressionVisitor.cs
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smitpatel
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Oct 22, 2019
...onalShapedQueryCompilingExpressionVisitor.ParameterNullabilityOptimizingExpressionVisitor.cs
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...onalShapedQueryCompilingExpressionVisitor.ParameterNullabilityOptimizingExpressionVisitor.cs
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| var newOperand = (SqlExpression)Visit(sqlUnaryExpression.Operand); | ||
| if (newOperand is SqlParameterExpression parameterOperand) | ||
| { | ||
| var parameterValue = _parametersValues[parameterOperand.Name]; |
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Should use TryGetValue?
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Is it possible to get this far for a query with a parameter that doesn't have a value?
If yes then use TryGetValue and throw a nice exception and add a test.
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will do it in a different PR, we have a few places where we directly access parameterValues elements, without TryGetValue - will update all of them
smitpatel
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Oct 22, 2019
...onalShapedQueryCompilingExpressionVisitor.ParameterNullabilityOptimizingExpressionVisitor.cs
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smitpatel
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Oct 22, 2019
This is part of #17543 - Queries really slow due to null checks Problem was that at the time we performed null semantics and related optimizations we didn't know the value of parameters, so we always had to assume they can be nullable, which resulted in additional IS NULL checks being created. However, later in the pipeline we know the parameter values and we can optimize out those checks for parameters whose values are not null.
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This is part of #17543 - Queries really slow due to null checks
Problem was that at the time we performed null semantics and related optimizations we didn't know the value of parameters, so we always had to assume they can be nullable, which resulted in additional IS NULL checks being created.
However, later in the pipeline we know the parameter values and we can optimize out those checks for parameters whose values are not null.