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Relational: Implement split query for non-include collections
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Resolves #21234
Resolves #22283
Resolves #23803
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smitpatel committed Apr 21, 2021
1 parent 438b05f commit 883bcc1
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3 changes: 0 additions & 3 deletions src/EFCore.Relational/Properties/RelationalStrings.resx
Original file line number Diff line number Diff line change
Expand Up @@ -748,9 +748,6 @@
<data name="UnableToBindMemberToEntityProjection" xml:space="preserve">
<value>Unable to bind '{memberType}.{member}' to an entity projection of '{entityType}'.</value>
</data>
<data name="UnableToSplitCollectionProjectionInSplitQuery" xml:space="preserve">
<value>The query has been configured to use '{splitQueryEnumValue}', but contains a collection in the 'Select' call which could not be split into a separate query. Remove '{splitQueryMethodName}' if applied, or add '{singleQueryMethodName}' to the query.</value>
</data>
<data name="UnhandledExpressionInVisitor" xml:space="preserve">
<value>Unhandled expression '{expression}' of type '{expressionType}' encountered in '{visitor}'.</value>
</data>
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This file was deleted.

Original file line number Diff line number Diff line change
Expand Up @@ -44,15 +44,5 @@ public override Expression NormalizeQueryableMethod(Expression expression)

return expression;
}

/// <inheritdoc />
public override Expression Process(Expression query)
{
query = base.Process(query);

return _relationalQueryCompilationContext.QuerySplittingBehavior == QuerySplittingBehavior.SplitQuery
? new SplitIncludeRewritingExpressionVisitor().Visit(query)
: query;
}
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@ namespace Microsoft.EntityFrameworkCore.Query.SqlExpressions
/// not used in application code.
/// </para>
/// </summary>
public class FromSqlExpression : TableExpressionBase
public class FromSqlExpression : TableExpressionBase, ICloneable
{
/// <summary>
/// Creates a new instance of the <see cref="FromSqlExpression" /> class.
Expand Down Expand Up @@ -95,6 +95,9 @@ protected override Expression VisitChildren(ExpressionVisitor visitor)
return this;
}

/// <inheritdoc />
public virtual object Clone() => new FromSqlExpression(Alias, Sql, Arguments);

/// <inheritdoc />
protected override void Print(ExpressionPrinter expressionPrinter)
{
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Original file line number Diff line number Diff line change
Expand Up @@ -712,11 +712,15 @@ public SelectExpressionVerifyingExpressionVisitor(IEnumerable<TableReferenceExpr
Visit(childIdentifier.Column);
}

break;
return selectExpression;

case ConcreteColumnExpression concreteColumnExpression:
concreteColumnExpression.Verify(_tableReferencesInScope);
break;
return concreteColumnExpression;

case ShapedQueryExpression shapedQueryExpression:
Verify(shapedQueryExpression.QueryExpression, _tableReferencesInScope);
return shapedQueryExpression;
}

return base.Visit(expression);
Expand All @@ -727,5 +731,95 @@ public static void Verify(Expression expression, IEnumerable<TableReferenceExpre
=> new SelectExpressionVerifyingExpressionVisitor(tableReferencesInScope)
.Visit(expression);
}

private sealed class CloningExpressionVisitor : ExpressionVisitor
{
[return: NotNullIfNotNull("expression")]
public override Expression? Visit(Expression? expression)
{
if (expression is SelectExpression selectExpression)
{
// We ignore projection binding related elements as we don't want to copy them over for top level
// Nested level will have _projection populated and no binding elements
var newProjections = selectExpression._projection.Select(Visit).ToList<ProjectionExpression>();

var newTables = selectExpression._tables.Select(Visit).ToList<TableExpressionBase>();
// Since we are cloning we need to generate new table references
// In other cases (like VisitChildren), we just reuse the same table references and update the SelectExpression inside it.
// We initially assign old SelectExpression in table references and later update it once we construct clone
var newTableReferences = selectExpression._tableReferences
.Select(e => new TableReferenceExpression(selectExpression, e.Alias)).ToList();
Check.DebugAssert(
newTables.Select(e => GetAliasFromTableExpressionBase(e)).SequenceEqual(newTableReferences.Select(e => e.Alias)),
"Alias of updated tables must match the old tables.");

var predicate = (SqlExpression?)Visit(selectExpression.Predicate);
var newGroupBy = selectExpression._groupBy.Select(Visit)
.Where(e => !(e is SqlConstantExpression || e is SqlParameterExpression))
.ToList<SqlExpression>();
var havingExpression = (SqlExpression?)Visit(selectExpression.Having);
var newOrderings = selectExpression._orderings.Select(Visit).ToList<OrderingExpression>();
var offset = (SqlExpression?)Visit(selectExpression.Offset);
var limit = (SqlExpression?)Visit(selectExpression.Limit);

var newSelectExpression = new SelectExpression(selectExpression.Alias, newProjections, newTables, newTableReferences, newGroupBy, newOrderings)
{
Predicate = predicate,
Having = havingExpression,
Offset = offset,
Limit = limit,
IsDistinct = selectExpression.IsDistinct,
Tags = selectExpression.Tags,
_usedAliases = selectExpression._usedAliases.ToHashSet()
};

newSelectExpression._tptLeftJoinTables.AddRange(selectExpression._tptLeftJoinTables);
// Since identifiers are ColumnExpression, they are not visited since they don't contain SelectExpression inside it.
newSelectExpression._identifier.AddRange(selectExpression._identifier);
newSelectExpression._childIdentifiers.AddRange(selectExpression._childIdentifiers);

// Remap tableReferences in new select expression
foreach (var tableReference in newTableReferences)
{
tableReference.UpdateTableReference(selectExpression, newSelectExpression);
}

// Now that we have SelectExpression, we visit all components and update table references inside columns
newSelectExpression = (SelectExpression)new ColumnExpressionReplacingExpressionVisitor(selectExpression, newSelectExpression)
.Visit(newSelectExpression);

return newSelectExpression;

}

return expression is ICloneable cloneable ? (Expression)cloneable.Clone() : base.Visit(expression);
}
}

private sealed class ColumnExpressionReplacingExpressionVisitor : ExpressionVisitor
{
private readonly SelectExpression _oldSelectExpression;
private readonly Dictionary<string, TableReferenceExpression> _newTableReferences;

public ColumnExpressionReplacingExpressionVisitor(SelectExpression oldSelectExpression, SelectExpression newSelectExpression)
{
_oldSelectExpression = oldSelectExpression;
_newTableReferences = newSelectExpression._tableReferences.ToDictionary(e => e.Alias);
}

[return: NotNullIfNotNull("expression")]
public override Expression? Visit(Expression? expression)
{
return expression is ConcreteColumnExpression concreteColumnExpression
&& _oldSelectExpression.ContainsTableReference(concreteColumnExpression)
? new ConcreteColumnExpression(
concreteColumnExpression.Name,
_newTableReferences[concreteColumnExpression.TableAlias],
concreteColumnExpression.Type,
concreteColumnExpression.TypeMapping!,
concreteColumnExpression.IsNullable)
: base.Visit(expression);
}
}
}
}
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