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Allow using TDS Endpoint for non-recursive CTEs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,144 @@ | ||
| using System; | ||
| using System.Collections.Generic; | ||
| using System.Text; | ||
| using Microsoft.SqlServer.TransactSql.ScriptDom; | ||
|
|
||
| namespace MarkMpn.Sql4Cds.Engine.Visitors | ||
| { | ||
| /// <summary> | ||
| /// Checks the properties of a CTE to ensure it is valid | ||
| /// </summary> | ||
| /// <remarks> | ||
| /// https://learn.microsoft.com/en-us/sql/t-sql/queries/with-common-table-expression-transact-sql?view=sql-server-ver16 | ||
| /// </remarks> | ||
| class CteValidatorVisitor : TSqlFragmentVisitor | ||
| { | ||
| private int _cteReferenceCount; | ||
| private FunctionCall _scalarAggregate; | ||
| private ScalarSubquery _subquery; | ||
| private QualifiedJoin _outerJoin; | ||
|
|
||
| public string Name { get; private set; } | ||
|
|
||
| public bool IsRecursive { get; private set; } | ||
|
|
||
| public override void Visit(CommonTableExpression node) | ||
| { | ||
| Name = node.ExpressionName.Value; | ||
|
|
||
| base.Visit(node); | ||
| } | ||
|
|
||
| public override void Visit(FromClause node) | ||
| { | ||
| _cteReferenceCount = 0; | ||
|
|
||
| base.Visit(node); | ||
|
|
||
| // The FROM clause of a recursive member must refer only one time to the CTE expression_name. | ||
| if (_cteReferenceCount > 1) | ||
| throw new NotSupportedQueryFragmentException("Recursive CTEs can only be referenced once", node); | ||
| } | ||
|
|
||
| public override void Visit(NamedTableReference node) | ||
| { | ||
| if (node.SchemaObject.Identifiers.Count == 1 && | ||
| node.SchemaObject.BaseIdentifier.Value.Equals(Name, StringComparison.OrdinalIgnoreCase)) | ||
| { | ||
| IsRecursive = true; | ||
| _cteReferenceCount++; | ||
|
|
||
| // The following items aren't allowed in the CTE_query_definition of a recursive member: | ||
| // A hint applied to a recursive reference to a CTE inside a CTE_query_definition. | ||
| if (node.TableHints.Count > 0) | ||
| throw new NotSupportedQueryFragmentException("Table hints are not supported in CTEs", node.TableHints[0]); | ||
| } | ||
|
|
||
| base.Visit(node); | ||
| } | ||
|
|
||
| public override void Visit(QualifiedJoin node) | ||
| { | ||
| base.Visit(node); | ||
|
|
||
| if (node.QualifiedJoinType != QualifiedJoinType.Inner) | ||
| _outerJoin = node; | ||
| } | ||
|
|
||
| public override void ExplicitVisit(BinaryQueryExpression node) | ||
| { | ||
| base.ExplicitVisit(node); | ||
|
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| // UNION ALL is the only set operator allowed between the last anchor member and first recursive member, and when combining multiple recursive members. | ||
| if (IsRecursive && (node.BinaryQueryExpressionType != BinaryQueryExpressionType.Union || !node.All)) | ||
| throw new NotSupportedQueryFragmentException("Recursive CTEs must have a UNION ALL between the anchor and recursive parts", node); | ||
| } | ||
|
|
||
| public override void Visit(QuerySpecification node) | ||
| { | ||
| _scalarAggregate = null; | ||
| _subquery = null; | ||
| _outerJoin = null; | ||
|
|
||
| base.Visit(node); | ||
|
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||
| // The following clauses can't be used in the CTE_query_definition: | ||
| // ORDER BY (except when a TOP clause is specified) | ||
| if (node.OrderByClause != null && node.TopRowFilter == null) | ||
| throw new NotSupportedQueryFragmentException("ORDER BY is not supported in CTEs", node.OrderByClause); | ||
|
|
||
| // FOR BROWSE | ||
| if (node.ForClause is BrowseForClause) | ||
| throw new NotSupportedQueryFragmentException("FOR BROWSE is not supported in CTEs", node.ForClause); | ||
|
|
||
| if (IsRecursive) | ||
| { | ||
| // The following items aren't allowed in the CTE_query_definition of a recursive member: | ||
| // SELECT DISTINCT | ||
| if (node.UniqueRowFilter == UniqueRowFilter.Distinct) | ||
| throw new NotSupportedQueryFragmentException("DISTINCT is not supported in CTEs", node); | ||
|
|
||
| // GROUP BY | ||
| if (node.GroupByClause != null) | ||
| throw new NotSupportedQueryFragmentException("GROUP BY is not supported in CTEs", node.GroupByClause); | ||
|
|
||
| // TODO: PIVOT | ||
|
|
||
| // HAVING | ||
| if (node.HavingClause != null) | ||
| throw new NotSupportedQueryFragmentException("HAVING is not supported in CTEs", node.HavingClause); | ||
|
|
||
| // Scalar aggregation | ||
| if (_scalarAggregate != null) | ||
| throw new NotSupportedQueryFragmentException("Scalar aggregation is not supported in CTEs", _scalarAggregate); | ||
|
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||
| // TOP | ||
| if (node.TopRowFilter != null) | ||
| throw new NotSupportedQueryFragmentException("TOP is not supported in CTEs", node.TopRowFilter); | ||
|
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||
| // LEFT, RIGHT, OUTER JOIN (INNER JOIN is allowed) | ||
| if (_outerJoin != null) | ||
| throw new NotSupportedQueryFragmentException("Outer joins are not supported in CTEs", _outerJoin); | ||
|
|
||
| // Subqueries | ||
| if (_subquery != null) | ||
| throw new NotSupportedQueryFragmentException("Subqueries are not supported in CTEs", _subquery); | ||
| } | ||
| } | ||
|
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| public override void Visit(SelectStatement node) | ||
| { | ||
| base.Visit(node); | ||
|
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| // The following clauses can't be used in the CTE_query_definition: | ||
| // INTO | ||
| if (node.Into != null) | ||
| throw new NotSupportedQueryFragmentException("INTO is not supported in CTEs", node.Into); | ||
|
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||
| // OPTION clause with query hints | ||
| if (node.OptimizerHints.Count > 0) | ||
| throw new NotSupportedQueryFragmentException("Optimizer hints are not supported in CTEs", node.OptimizerHints[0]); | ||
|
|
||
| } | ||
| } | ||
| } |
109 changes: 109 additions & 0 deletions
109
MarkMpn.Sql4Cds.Engine/Visitors/ReplaceCtesWithSubqueriesVisitor.cs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,109 @@ | ||
| using System; | ||
| using System.Collections.Generic; | ||
| using System.Text; | ||
| using Microsoft.SqlServer.TransactSql.ScriptDom; | ||
|
|
||
| namespace MarkMpn.Sql4Cds.Engine.Visitors | ||
| { | ||
| /// <summary> | ||
| /// Finds references to non-recursive CTEs and replaces them with subqueries | ||
| /// </summary> | ||
| class ReplaceCtesWithSubqueriesVisitor : TSqlFragmentVisitor | ||
| { | ||
| private Dictionary<string, CommonTableExpression> _cteQueries; | ||
|
|
||
| public ReplaceCtesWithSubqueriesVisitor() | ||
| { | ||
| _cteQueries = new Dictionary<string, CommonTableExpression>(StringComparer.OrdinalIgnoreCase); | ||
| } | ||
|
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||
| public override void Visit(CommonTableExpression node) | ||
| { | ||
| base.Visit(node); | ||
|
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| _cteQueries[node.ExpressionName.Value] = node; | ||
| } | ||
|
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| public override void Visit(SelectStatement node) | ||
| { | ||
| // Visit the CTEs first | ||
| if (node.WithCtesAndXmlNamespaces != null) | ||
| node.WithCtesAndXmlNamespaces.Accept(this); | ||
|
|
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| base.Visit(node); | ||
|
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||
| // Should have visited the CTEs now, so remove them from the query | ||
| node.WithCtesAndXmlNamespaces = null; | ||
| } | ||
|
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| public override void Visit(FromClause node) | ||
| { | ||
| base.Visit(node); | ||
|
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| for (var i = 0; i < node.TableReferences.Count; i++) | ||
| { | ||
| if (node.TableReferences[i] is NamedTableReference ntr && | ||
| TryGetCteDefinition(ntr, out var subquery)) | ||
| { | ||
| node.TableReferences[i] = subquery; | ||
| } | ||
| } | ||
| } | ||
|
|
||
| public override void Visit(QualifiedJoin node) | ||
| { | ||
| base.Visit(node); | ||
|
|
||
| if (node.FirstTableReference is NamedTableReference table1 && | ||
| TryGetCteDefinition(table1, out var subquery1)) | ||
| { | ||
| node.FirstTableReference = subquery1; | ||
| } | ||
|
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||
| if (node.SecondTableReference is NamedTableReference table2 && | ||
| TryGetCteDefinition(table2, out var subquery2)) | ||
| { | ||
| node.SecondTableReference = subquery2; | ||
| } | ||
| } | ||
|
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| public override void Visit(UnqualifiedJoin node) | ||
| { | ||
| base.Visit(node); | ||
|
|
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| if (node.FirstTableReference is NamedTableReference table1 && | ||
| TryGetCteDefinition(table1, out var subquery1)) | ||
| { | ||
| node.FirstTableReference = subquery1; | ||
| } | ||
|
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||
| if (node.SecondTableReference is NamedTableReference table2 && | ||
| TryGetCteDefinition(table2, out var subquery2)) | ||
| { | ||
| node.SecondTableReference = subquery2; | ||
| } | ||
| } | ||
|
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| private bool TryGetCteDefinition(NamedTableReference table, out QueryDerivedTable subquery) | ||
| { | ||
| subquery = null; | ||
|
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| if (table.SchemaObject.Identifiers.Count > 1) | ||
| return false; | ||
|
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| if (!_cteQueries.TryGetValue(table.SchemaObject.BaseIdentifier.Value, out var cte)) | ||
| return false; | ||
|
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| subquery = new QueryDerivedTable | ||
| { | ||
| Alias = table.Alias ?? cte.ExpressionName, | ||
| QueryExpression = cte.QueryExpression | ||
| }; | ||
|
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| foreach (var col in cte.Columns) | ||
| subquery.Columns.Add(col); | ||
|
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| return true; | ||
| } | ||
| } | ||
| } |
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