/// <summary>
/// Gets the rows for the join.
/// </summary>
/// <param name="context">
/// The context.
/// </param>
/// <param name="multiPartQuery">
/// The multi part query.
/// </param>
/// <returns>
/// The <see cref="IAsyncEnumerable{Row}"/>.
/// </returns>
internal override IAsyncEnumerable <Row> GetRows(IInternalExecutionContext context, [NotNull] IMultiPartQuery multiPartQuery)
{
var rowBuilder = new RowBuilder();
//// Build the left part by filtering by parts that contain the fields of the left side.
var leftQuery = new MultiPartQuery
{
Fields = multiPartQuery.Fields.Where(f => this.Left.Aliases.Contains(f.SourceAlias)),
FilterExpression = multiPartQuery.FilterExpression.FilterByAliases(this.Left.Aliases),
WildcardAliases = multiPartQuery.WildcardAliases.Intersect(this.Left.Aliases).ToArray(),
};
//// Create the enumerable.
return(context.CreateAsyncEnumerable(
async() =>
{
//// Retrieve the records from the left side.
var leftData = await this.Left.GetRows(context, leftQuery).MaterializeAsync().ConfigureAwait(false);
var rightQuery = new MultiPartQuery
{
Fields = multiPartQuery.Fields.Where(f => this.Right.Aliases.Contains(f.SourceAlias)),
FilterExpression = CrossJoin.RangesToJoinFilter(await this.FindRangesAsync(context, multiPartQuery.FilterExpression, leftData)),
WildcardAliases = multiPartQuery.WildcardAliases.Intersect(this.Right.Aliases),
};
var rightData = await this.Right.GetRows(context, rightQuery).MaterializeAsync().ConfigureAwait(false);
return leftData.CrossJoin(rightData, rowBuilder.CombineRows);
})
.Where(multiPartQuery.FilterExpression.GetRowFilter())
.OrderBy(multiPartQuery.OrderByExpressions)
.AfterLastElement(count => context.Logger.Verbose($"{this.GetType().Name} returned {count} records.")));
}
protected virtual JoinQuery CreateJoinQuery(IExecutionContext context, [NotNull] IMultiPartQuery query)
{
var filter = query.GetFilter(context);
var leftFilter = filter.RemoveAllPartsThatAreNotInSource(this.Left);
var rightFilter = filter.RemoveAllPartsThatAreNotInSource(this.Right);
var resultFilter = filter.SplitByAndExpressions()
.Except(leftFilter.SplitByAndExpressions(), JoinSourceBase.ExpressionComparer)
.Except(rightFilter.SplitByAndExpressions(), JoinSourceBase.ExpressionComparer)
.DefaultIfEmpty()
.Aggregate(Expression.AndAlso);
var leftQuery = new MultiPartQuery
{
Fields = query.GetUsedFields(this.Left, resultFilter),
FilterExpression = leftFilter,
};
var rightQuery = new MultiPartQuery
{
Fields = query.GetUsedFields(this.Right, resultFilter),
FilterExpression = leftFilter,
};
return(new JoinQuery(leftQuery, rightQuery, resultFilter, query.OrderByExpressions));
}
/// <summary>
/// Gets the rows for the join.
/// </summary>
/// <param name="context">
/// The context.
/// </param>
/// <param name="multiPartQuery">
/// The multi part query.
/// </param>
/// <returns>
/// The <see cref="IAsyncEnumerable{Row}"/>.
/// </returns>
internal override IAsyncEnumerable <Row> GetRows(IInternalExecutionContext context, [NotNull] IMultiPartQuery multiPartQuery)
{
var rowBuilder = new RowBuilder();
//// For a join, we can append the filter expression (WHERE part) with the filter for the join.
var filterExpression = multiPartQuery.FilterExpression == null ? this.Filter : Expression.AndAlso(multiPartQuery.FilterExpression, this.Filter);
//// Build the left part by filtering by parts that contain the fields of the left side.
var leftQuery = new MultiPartQuery
{
Fields = multiPartQuery.Fields.Where(f => this.Left.Aliases.Contains(f.SourceAlias)).Union(this.Filter.GetFields().Where(f => this.Left.Aliases.Contains(f.SourceAlias))),
FilterExpression = filterExpression.FilterByAliases(this.Left.Aliases).Simplify(context),
WildcardAliases = multiPartQuery.WildcardAliases.Intersect(this.Left.Aliases).ToArray(),
};
//// Create the enumerable.
return(context.CreateAsyncEnumerable(
async() =>
{
//// Split by OR-expressions,
var joinsParts = this.Filter.SplitByOrExpressions()
//// Then, re-order AND expressions, so the most specific comparer is in front.
.Select(part => part.Simplify(context).SplitByAndExpressions().Cast <CompareExpression>()
.Select(c => c.MoveFieldsToTheLeft(this.Left))
.OrderBy(p => p, MostSpecificComparer.Default)
.ToArray())
.ToArray();
//// Retrieve the records from the left side.
var leftData = await this.Left.GetRows(context, leftQuery).MaterializeAsync().ConfigureAwait(false);
if (leftData.Count == 0)
{
return context.CreateEmptyAsyncEnumerable <Row>();
}
//// Build the right query, by using the
var rightQuery = new MultiPartQuery
{
Fields = multiPartQuery.Fields.Where(f => this.Right.Aliases.Contains(f.SourceAlias)).Union(this.Filter.GetDataSourceFields(this.Right)),
FilterExpression = JoinBase.RangesToJoinFilter(await this.FindRangesAsync(context, filterExpression, leftData)),
WildcardAliases = multiPartQuery.WildcardAliases.Intersect(this.Right.Aliases),
};
var rightData = await this.Right.GetRows(context, rightQuery).MaterializeAsync().ConfigureAwait(false);
var result = this.CombineResults(joinsParts, rowBuilder, leftData, rightData);
result = await result.MaterializeAsync();
return result;
})
.Where(multiPartQuery.FilterExpression.GetRowFilter())
.OrderBy(multiPartQuery.OrderByExpressions)
.AfterLastElement(count => context.Logger.Verbose($"{this.GetType().Name} returned {count} records.")));
}
protected override JoinQuery CreateJoinQuery(IExecutionContext context, [NotNull] IMultiPartQuery query)
{
var resultFilter = query.GetFilter(context);
var leftQuery = new MultiPartQuery
{
Fields = query.GetUsedFields(this.Left, resultFilter),
};
var rightQuery = new MultiPartQuery
{
Fields = query.GetUsedFields(this.Right, resultFilter),
};
return(new JoinQuery(leftQuery, rightQuery, resultFilter, query.OrderByExpressions));
}
/// <summary>
/// Gets the rows for the join.
/// </summary>
/// <param name="context">
/// The context.
/// </param>
/// <param name="multiPartQuery">
/// The multi part query.
/// </param>
/// <returns>
/// The <see cref="IAsyncEnumerable{Row}"/>.
/// </returns>
internal override IAsyncEnumerable <Row> GetRows(IInternalExecutionContext context, [NotNull] IMultiPartQuery multiPartQuery)
{
var rowBuilder = new RowBuilder();
//// Build the left part by filtering by parts that contain the fields of the left side.
var leftQuery = new MultiPartQuery
{
Fields = multiPartQuery.Fields.Where(f => this.left.Aliases.Contains(f.SourceAlias)),
WildcardAliases = multiPartQuery.WildcardAliases.Intersect(this.left.Aliases).ToArray(),
};
var rightQuery = new MultiPartQuery
{
Fields = multiPartQuery.Fields.Where(f => this.right.Aliases.Contains(f.SourceAlias)),
WildcardAliases = multiPartQuery.WildcardAliases.Intersect(this.right.Aliases),
};
return(this.left.GetRows(context, leftQuery).ZipAll(this.right.GetRows(context, rightQuery), rowBuilder.CombineRows)
.Where(multiPartQuery.FilterExpression.GetRowFilter())
.OrderBy(multiPartQuery.OrderByExpressions)
.AfterLastElement(count => context.Logger.Verbose($"{this.GetType().Name} returned {count} records.")));
}
/// <summary>
/// Combines the left and right result sets.
/// </summary>
/// <param name="context">
/// The context.
/// </param>
/// <param name="leftData">
/// The left result set.
/// </param>
/// <param name="rightData">
/// The right result set.
/// </param>
/// <param name="rightQuery">
/// The query for the right side.
/// </param>
/// <param name="rowBuilder">
/// The row builder.
/// </param>
/// <returns>
/// The <see cref="IAsyncEnumerable{Row}"/>.
/// </returns>
protected abstract IAsyncEnumerable <Row> CombineResults(IInternalExecutionContext context, IAsyncReadOnlyCollection <Row> leftData, IAsyncReadOnlyCollection <Row> rightData, MultiPartQuery rightQuery, RowBuilder rowBuilder);
/// <summary>
/// Combines the left and right result sets.
/// </summary>
/// <param name="context">
/// The context.
/// </param>
/// <param name="leftData">
/// The left result set.
/// </param>
/// <param name="rightData">
/// The right result set.
/// </param>
/// <param name="rightQuery">
/// The query for the right side.
/// </param>
/// <param name="rowBuilder">
/// The row builder.
/// </param>
/// <returns>
/// The <see cref="IAsyncEnumerable{Row}"/>.
/// </returns>
protected override IAsyncEnumerable <Row> CombineResults(IInternalExecutionContext context, IAsyncReadOnlyCollection <Row> leftData, IAsyncReadOnlyCollection <Row> rightData, MultiPartQuery rightQuery, [NotNull] RowBuilder rowBuilder)
{
return(this.RightFactory != null
? leftData.CrossApply(row => this.RightFactory(context, row).GetRows(context, rightQuery), rowBuilder.CombineRows)
: leftData.CrossApply(row => rightData, rowBuilder.CombineRows));
}
protected virtual JoinQuery CreateJoinQuery(IExecutionContext context, [NotNull] IMultiPartQuery query, Expression joinFilter)
{
var filterParts = (query.FilterExpression == null ? joinFilter : Expression.AndAlso(query.GetFilter(context), joinFilter)).SplitByAndExpressions();
// Get all parts of the query that contain fields from both sources.
var joinParts = filterParts.OfType <CompareExpression>()
.Where(comparison =>
{
var fields = comparison.GetFields().Select(f => f.SourceAlias).ToArray();
return(fields.Intersect(this.Left.Aliases).Any() && fields.Intersect(this.Right.Aliases).Any());
})
.ToArray();
// What's left are the filters for only one source. These we can split in a left part, a right part, and a filter part over the result.
var filter = filterParts.Except(joinParts, new ExpressionComparer()).DefaultIfEmpty().Aggregate(Expression.AndAlso);
var leftFilter = filter.RemoveAllPartsThatAreNotInSource(this.Left);
var rightFilter = filter.RemoveAllPartsThatAreNotInSource(this.Right);
var resultFilter = filter.Except(leftFilter, rightFilter);
var joinExpression = joinParts.OrderBy(p => p, new MostSpecificComparer()).First().MoveFieldsToTheLeft(this.Left);
var ascending = joinExpression.CompareType != ExpressionType.GreaterThan && joinExpression.CompareType != ExpressionType.GreaterThanOrEqual;
var leftQuery = new MultiPartQuery
{
Fields = query.Fields
.Where(f => this.Left.Aliases.Contains(f.SourceAlias))
.Concat(joinParts.SelectMany(l => l.GetDataSourceFields(this.Left)))
.Concat(resultFilter.GetDataSourceFields(this.Left))
.Distinct(),
FilterExpression = leftFilter,
OrderByExpressions = new[]
{
new OrderByExpression(joinExpression.Left, ascending)
},
};
var rightQuery = new MultiPartQuery
{
Fields = query.Fields
.Where(f => this.Right.Aliases.Contains(f.SourceAlias))
.Concat(joinParts.SelectMany(l => l.GetDataSourceFields(this.Right)))
.Concat(resultFilter.GetDataSourceFields(this.Right))
.Distinct(),
FilterExpression = rightFilter,
OrderByExpressions = new[]
{
new OrderByExpression(joinExpression.Right, ascending)
},
};
var exraJoinFilter = GenericVisitor.Visit(
(ExecutionContextExpression e) => Expression.Constant(context),
joinParts.Skip(1).DefaultIfEmpty().Aggregate <Expression>(Expression.AndAlso));
return(new JoinQuery(
leftQuery,
rightQuery,
joinExpression.Left.GetRowExpression <Row>(),
joinExpression.CompareType,
joinExpression.Right.GetRowExpression <Row>(),
joinParts.DefaultIfEmpty <Expression>().Aggregate(Expression.AndAlso),
exraJoinFilter.GetJoinFunction(this.Left),
query.OrderByExpressions,
resultFilter));
}
