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Query: Translate Distinct operator over group element before aggregate
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Resolves #17376
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@smitpatel
smitpatel committed Aug 3, 2020
1 parent 2c2df44 commit de67a91
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Showing 10 changed files with 491 additions and 210 deletions.
120 changes: 74 additions & 46 deletions src/EFCore.InMemory/Query/Internal/InMemoryExpressionTranslatingExpressionVisitor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,6 @@
using JetBrains.Annotations;
using Microsoft.EntityFrameworkCore.Diagnostics;
using Microsoft.EntityFrameworkCore.Infrastructure;
using Microsoft.EntityFrameworkCore.InMemory.Internal;
using Microsoft.EntityFrameworkCore.Metadata;
using Microsoft.EntityFrameworkCore.Query;
using Microsoft.EntityFrameworkCore.Storage;
Expand Down Expand Up @@ -414,14 +413,11 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCallExp
groupingElementExpression, methodCallExpression.Arguments[1].UnwrapLambdaFromQuote());
}

var selector = GetSelector(groupingElementExpression);
var expression = ApplySelect(groupingElementExpression);

result = selector == null
result = expression == null
? null
: Expression.Call(
EnumerableMethods.GetAverageWithSelector(selector.ReturnType).MakeGenericMethod(typeof(ValueBuffer)),
groupingElementExpression.Source,
selector);
: Expression.Call(EnumerableMethods.GetAverageWithoutSelector(expression.Type.TryGetSequenceType()), expression);
break;
}

Expand All @@ -439,12 +435,24 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCallExp
}
}

result = Expression.Call(
EnumerableMethods.CountWithoutPredicate.MakeGenericMethod(typeof(ValueBuffer)),
groupingElementExpression.Source);
var expression = ApplySelect(groupingElementExpression);

result = expression == null
? null
: Expression.Call(
EnumerableMethods.CountWithoutPredicate.MakeGenericMethod(expression.Type.TryGetSequenceType()),
expression);
break;
}

case nameof(Enumerable.Distinct):
result = groupingElementExpression.Selector is EntityShaperExpression
? groupingElementExpression
: groupingElementExpression.IsDistinct
? null
: groupingElementExpression.ApplyDistinct();
break;

case nameof(Enumerable.LongCount):
{
if (methodCallExpression.Arguments.Count == 2)
Expand All @@ -459,9 +467,13 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCallExp
}
}

result = Expression.Call(
EnumerableMethods.LongCountWithoutPredicate.MakeGenericMethod(typeof(ValueBuffer)),
groupingElementExpression.Source);
var expression = ApplySelect(groupingElementExpression);

result = expression == null
? null
: Expression.Call(
EnumerableMethods.LongCountWithoutPredicate.MakeGenericMethod(expression.Type.TryGetSequenceType()),
expression);
break;
}

Expand All @@ -473,22 +485,20 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCallExp
groupingElementExpression, methodCallExpression.Arguments[1].UnwrapLambdaFromQuote());
}

var selector = GetSelector(groupingElementExpression);
if (selector != null)
var expression = ApplySelect(groupingElementExpression);
if (expression == null)
{
var aggregateMethod = EnumerableMethods.GetMaxWithSelector(selector.ReturnType);
aggregateMethod = aggregateMethod.GetGenericArguments().Length == 2
? aggregateMethod.MakeGenericMethod(typeof(ValueBuffer), selector.ReturnType)
: aggregateMethod.MakeGenericMethod(typeof(ValueBuffer));


result = Expression.Call(aggregateMethod, groupingElementExpression.Source, selector);
result = null;
}
else

var type = expression.Type.TryGetSequenceType();
var aggregateMethod = EnumerableMethods.GetMaxWithoutSelector(type);
if (aggregateMethod.IsGenericMethod)
{
result = null;
aggregateMethod = aggregateMethod.MakeGenericMethod(type);
}

result = Expression.Call(aggregateMethod, expression);
break;
}

Expand All @@ -500,23 +510,20 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCallExp
groupingElementExpression, methodCallExpression.Arguments[1].UnwrapLambdaFromQuote());
}

var selector = GetSelector(groupingElementExpression);

if (selector != null)
var expression = ApplySelect(groupingElementExpression);
if (expression == null)
{
var aggregateMethod = EnumerableMethods.GetMinWithSelector(selector.ReturnType);
aggregateMethod = aggregateMethod.GetGenericArguments().Length == 2
? aggregateMethod.MakeGenericMethod(typeof(ValueBuffer), selector.ReturnType)
: aggregateMethod.MakeGenericMethod(typeof(ValueBuffer));


result = Expression.Call(aggregateMethod, groupingElementExpression.Source, selector);
result = null;
}
else

var type = expression.Type.TryGetSequenceType();
var aggregateMethod = EnumerableMethods.GetMinWithoutSelector(type);
if (aggregateMethod.IsGenericMethod)
{
result = null;
aggregateMethod = aggregateMethod.MakeGenericMethod(type);
}

result = Expression.Call(aggregateMethod, expression);
break;
}

Expand All @@ -532,14 +539,11 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCallExp
groupingElementExpression, methodCallExpression.Arguments[1].UnwrapLambdaFromQuote());
}

var selector = GetSelector(groupingElementExpression);
var expression = ApplySelect(groupingElementExpression);

result = selector == null
result = expression == null
? null
: Expression.Call(
EnumerableMethods.GetSumWithSelector(selector.ReturnType).MakeGenericMethod(typeof(ValueBuffer)),
groupingElementExpression.Source,
selector);
: Expression.Call(EnumerableMethods.GetSumWithoutSelector(expression.Type.TryGetSequenceType()), expression);
break;
}

Expand Down Expand Up @@ -567,12 +571,30 @@ GroupingElementExpression ApplyPredicate(GroupingElementExpression groupingEleme
Expression.Lambda(predicate, groupingElement.ValueBufferParameter)));
}

LambdaExpression GetSelector(GroupingElementExpression groupingElement)
Expression ApplySelect(GroupingElementExpression groupingElement)
{
var selector = TranslateInternal(groupingElement.Selector);
return selector == null
? null
: Expression.Lambda(selector, groupingElement.ValueBufferParameter);

if (selector == null)
{
return groupingElement.Selector is EntityShaperExpression
? groupingElement.Source
: null;
}

var result = Expression.Call(
EnumerableMethods.Select.MakeGenericMethod(typeof(ValueBuffer), selector.Type),
groupingElement.Source,
Expression.Lambda(selector, groupingElement.ValueBufferParameter));

if (groupingElement.IsDistinct)
{
result = Expression.Call(
EnumerableMethods.Distinct.MakeGenericMethod(selector.Type),
result);
}

return result;
}

static GroupingElementExpression ApplySelector(GroupingElementExpression groupingElement, LambdaExpression lambdaExpression)
Expand Down Expand Up @@ -1571,9 +1593,15 @@ public GroupingElementExpression(Expression source, Expression selector, Paramet
Selector = selector;
}
public Expression Source { get; private set; }
public bool IsDistinct { get; private set; }
public Expression Selector { get; private set; }
public ParameterExpression ValueBufferParameter { get; }
public GroupingElementExpression ApplyDistinct()
{
IsDistinct = true;

return this;
}
public GroupingElementExpression ApplySelector(Expression expression)
{
Selector = expression;
Expand Down
12 changes: 12 additions & 0 deletions src/EFCore.Relational/Query/QuerySqlGenerator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -636,6 +636,18 @@ protected override Expression VisitCollate(CollateExpression collateExpresion)
return collateExpresion;
}

/// <inheritdoc />
protected override Expression VisitDistinctSql(DistinctSqlExpression distinctSqlExpression)
{
Check.NotNull(distinctSqlExpression, nameof(distinctSqlExpression));

_relationalCommandBuilder.Append("DISTINCT (");
Visit(distinctSqlExpression.Operand);
_relationalCommandBuilder.Append(")");

return distinctSqlExpression;
}

/// <inheritdoc />
protected override Expression VisitCase(CaseExpression caseExpression)
{
Expand Down
23 changes: 20 additions & 3 deletions src/EFCore.Relational/Query/RelationalSqlTranslatingExpressionVisitor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -156,8 +156,11 @@ public virtual SqlExpression TranslateAverage([NotNull] SqlExpression sqlExpress
if (inputType == typeof(int)
|| inputType == typeof(long))
{
sqlExpression = _sqlExpressionFactory.ApplyDefaultTypeMapping(
_sqlExpressionFactory.Convert(sqlExpression, typeof(double)));
sqlExpression = sqlExpression is DistinctSqlExpression distinctSqlExpression
? new DistinctSqlExpression(_sqlExpressionFactory.ApplyDefaultTypeMapping(
_sqlExpressionFactory.Convert(distinctSqlExpression.Operand, typeof(double))))
: _sqlExpressionFactory.ApplyDefaultTypeMapping(
_sqlExpressionFactory.Convert(sqlExpression, typeof(double)));
}

return inputType == typeof(float)
Expand Down Expand Up @@ -492,6 +495,14 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCallExp
result = TranslateCount(GetExpressionForAggregation(groupingElementExpression, starProjection: true));
break;

case nameof(Enumerable.Distinct):
result = groupingElementExpression.Element is EntityShaperExpression
? groupingElementExpression
: groupingElementExpression.IsDistinct
? null
: groupingElementExpression.ApplyDistinct();
break;

case nameof(Enumerable.LongCount):
if (methodCallExpression.Arguments.Count == 2)
{
Expand Down Expand Up @@ -600,14 +611,20 @@ SqlExpression GetExpressionForAggregation(GroupingElementExpression groupingElem
selector = _sqlExpressionFactory.Constant(1);
}

return _sqlExpressionFactory.Case(
selector = _sqlExpressionFactory.Case(
new List<CaseWhenClause>
{
new CaseWhenClause(groupingElement.Predicate, selector)
},
elseResult: null);
}

if (groupingElement.IsDistinct
&& !(selector is SqlFragmentExpression))
{
selector = new DistinctSqlExpression(selector);
}

return selector;
}
}
Expand Down
9 changes: 6 additions & 3 deletions src/EFCore.Relational/Query/SqlExpressionFactory.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,7 @@ public virtual SqlExpression ApplyTypeMapping(SqlExpression sqlExpression, Relat
{
CaseExpression e => ApplyTypeMappingOnCase(e, typeMapping),
CollateExpression e => ApplyTypeMappingOnCollate(e, typeMapping),
DistinctSqlExpression e => ApplyTypeMappingOnDistinctSql(e, typeMapping),
LikeExpression e => ApplyTypeMappingOnLike(e),
SqlBinaryExpression e => ApplyTypeMappingOnSqlBinary(e, typeMapping),
SqlUnaryExpression e => ApplyTypeMappingOnSqlUnary(e, typeMapping),
Expand Down Expand Up @@ -108,9 +109,11 @@ private SqlExpression ApplyTypeMappingOnCase(

private SqlExpression ApplyTypeMappingOnCollate(
CollateExpression collateExpression, RelationalTypeMapping typeMapping)
=> new CollateExpression(
ApplyTypeMapping(collateExpression.Operand, typeMapping),
collateExpression.Collation);
=> collateExpression.Update(ApplyTypeMapping(collateExpression.Operand, typeMapping));

private SqlExpression ApplyTypeMappingOnDistinctSql(
DistinctSqlExpression distinctSqlExpression, RelationalTypeMapping typeMapping)
=> distinctSqlExpression.Update(ApplyTypeMapping(distinctSqlExpression.Operand, typeMapping));

private SqlExpression ApplyTypeMappingOnSqlUnary(
SqlUnaryExpression sqlUnaryExpression, RelationalTypeMapping typeMapping)
Expand Down
9 changes: 9 additions & 0 deletions src/EFCore.Relational/Query/SqlExpressionVisitor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,9 @@ protected override Expression VisitExtension(Expression extensionExpression)
case CrossJoinExpression crossJoinExpression:
return VisitCrossJoin(crossJoinExpression);

case DistinctSqlExpression distinctSqlExpression:
return VisitDistinctSql(distinctSqlExpression);

case ExceptExpression exceptExpression:
return VisitExcept(exceptExpression);

Expand Down Expand Up @@ -149,6 +152,12 @@ protected override Expression VisitExtension(Expression extensionExpression)
/// <returns> The modified expression, if it or any subexpression was modified; otherwise, returns the original expression. </returns>
protected abstract Expression VisitCrossJoin([NotNull] CrossJoinExpression crossJoinExpression);
/// <summary>
/// Visits the children of the distinct SQL expression.
/// </summary>
/// <param name="distinctSqlExpression"> The expression to visit. </param>
/// <returns> The modified expression, if it or any subexpression was modified; otherwise, returns the original expression. </returns>
protected abstract Expression VisitDistinctSql([NotNull] DistinctSqlExpression distinctSqlExpression);
/// <summary>
/// Visits the children of the except expression.
/// </summary>
/// <param name="exceptExpression"> The expression to visit. </param>
Expand Down
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