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Merged
Shay Rojansky (roji) merged 2 commits into from
May 1, 2025
Merged

.Net: Evaluate MemberAccess of constants in filter translators #11750

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20f08ce
Evaluate MemberAccess of constants in filter translators
roji Apr 23, 2025
e8b3756
Fixes for Cosmos NoSQL
roji Apr 28, 2025
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4 changes: 2 additions & 2 deletions dotnet/src/Connectors/Connectors.Memory.AzureAISearch/AzureAISearchFilterTranslator.cs
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Expand Up @@ -31,8 +31,8 @@ internal string Translate(LambdaExpression lambdaExpression, VectorStoreRecordMo
Debug.Assert(lambdaExpression.Parameters.Count == 1);
this._recordParameter = lambdaExpression.Parameters[0];

var preprocessor = new FilterTranslationPreprocessor { InlineCapturedVariables = true };
var preprocessedExpression = preprocessor.Visit(lambdaExpression.Body);
var preprocessor = new FilterTranslationPreprocessor { SupportsParameterization = false };
var preprocessedExpression = preprocessor.Preprocess(lambdaExpression.Body);

this.Translate(preprocessedExpression);

Expand Down
4 changes: 2 additions & 2 deletions ...Connectors/Connectors.Memory.AzureCosmosDBMongoDB/AzureCosmosDBMongoDBFilterTranslator.cs
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Expand Up @@ -27,8 +27,8 @@ internal BsonDocument Translate(LambdaExpression lambdaExpression, VectorStoreRe
Debug.Assert(lambdaExpression.Parameters.Count == 1);
this._recordParameter = lambdaExpression.Parameters[0];

var preprocessor = new FilterTranslationPreprocessor { InlineCapturedVariables = true };
var preprocessedExpression = preprocessor.Visit(lambdaExpression.Body);
var preprocessor = new FilterTranslationPreprocessor { SupportsParameterization = false };
var preprocessedExpression = preprocessor.Preprocess(lambdaExpression.Body);

return this.Translate(preprocessedExpression);
}
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66 changes: 19 additions & 47 deletions ...src/Connectors/Connectors.Memory.AzureCosmosDBNoSQL/AzureCosmosDBNoSqlFilterTranslator.cs
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Expand Up @@ -6,8 +6,6 @@
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Text;
using Microsoft.Extensions.VectorData.ConnectorSupport;
using Microsoft.Extensions.VectorData.ConnectorSupport.Filter;
Expand All @@ -31,10 +29,10 @@ internal class AzureCosmosDBNoSqlFilterTranslator
Debug.Assert(lambdaExpression.Parameters.Count == 1);
this._recordParameter = lambdaExpression.Parameters[0];

var preprocessor = new FilterTranslationPreprocessor { InlineCapturedVariables = false };
var preprocessedExpression = preprocessor.Visit(lambdaExpression);
var preprocessor = new FilterTranslationPreprocessor { SupportsParameterization = true };
var preprocessedExpression = preprocessor.Preprocess(lambdaExpression.Body);

this.Translate(lambdaExpression.Body);
this.Translate(preprocessedExpression);

return (this._sql.ToString(), this._parameters);
}
Expand All @@ -51,6 +49,10 @@ private void Translate(Expression? node)
this.TranslateConstant(constant);
return;

case QueryParameterExpression { Name: var name, Value: var value }:
this.TranslateQueryParameter(name, value);
return;

case MemberExpression member:
this.TranslateMember(member);
return;
Expand Down Expand Up @@ -143,34 +145,13 @@ private void TranslateConstant(ConstantExpression constant)

private void TranslateMember(MemberExpression memberExpression)
{
switch (memberExpression)
if (this.TryBindProperty(memberExpression, out var property))
{
case var _ when this.TryBindProperty(memberExpression, out var property):
this.GeneratePropertyAccess(property);
return;

// Identify captured lambda variables, translate to Cosmos parameters (@foo, @bar...)
case var _ when TryGetCapturedValue(memberExpression, out var name, out var value):
// Duplicate parameter name, create a new parameter with a different name
// TODO: Share the same parameter when it references the same captured value
if (this._parameters.ContainsKey(name))
{
var baseName = name;
var i = 0;
do
{
name = baseName + (i++);
} while (this._parameters.ContainsKey(name));
}

name = '@' + name;
this._parameters.Add(name, value);
this._sql.Append(name);
return;

default:
throw new NotSupportedException($"Member access for '{memberExpression.Member.Name}' is unsupported - only member access over the filter parameter are supported");
this.GeneratePropertyAccess(property);
return;
}

throw new NotSupportedException($"Member access for '{memberExpression.Member.Name}' is unsupported - only member access over the filter parameter are supported");
}

private void TranslateNewArray(NewArrayExpression newArray)
Expand Down Expand Up @@ -264,6 +245,13 @@ private void TranslateUnary(UnaryExpression unary)
}
}

protected void TranslateQueryParameter(string name, object? value)
{
name = '@' + name;
this._parameters.Add(name, value);
this._sql.Append(name);
}

protected virtual void GeneratePropertyAccess(VectorStoreRecordPropertyModel property)
=> this._sql.Append(AzureCosmosDBNoSQLConstants.ContainerAlias).Append("[\"").Append(property.StorageName).Append("\"]");

Expand Down Expand Up @@ -312,20 +300,4 @@ private bool TryBindProperty(Expression expression, [NotNullWhen(true)] out Vect

return true;
}

private static bool TryGetCapturedValue(Expression expression, [NotNullWhen(true)] out string? name, out object? value)
{
if (expression is MemberExpression { Expression: ConstantExpression constant, Member: FieldInfo fieldInfo }
&& constant.Type.Attributes.HasFlag(TypeAttributes.NestedPrivate)
&& Attribute.IsDefined(constant.Type, typeof(CompilerGeneratedAttribute), inherit: true))
{
name = fieldInfo.Name;
value = fieldInfo.GetValue(constant.Value);
return true;
}

name = null;
value = null;
return false;
}
}
4 changes: 2 additions & 2 deletions dotnet/src/Connectors/Connectors.Memory.Common/SqlFilterTranslator.cs
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Expand Up @@ -42,8 +42,8 @@ internal void Translate(bool appendWhere)
this._sql.Append("WHERE ");
}

var preprocessor = new FilterTranslationPreprocessor { TransformCapturedVariablesToQueryParameterExpressions = true };
var preprocessedExpression = preprocessor.Visit(this._lambdaExpression.Body);
var preprocessor = new FilterTranslationPreprocessor { SupportsParameterization = true };
var preprocessedExpression = preprocessor.Preprocess(this._lambdaExpression.Body);

this.Translate(preprocessedExpression, isSearchCondition: true);
}
Expand Down
4 changes: 2 additions & 2 deletions dotnet/src/Connectors/Connectors.Memory.MongoDB/MongoDBFilterTranslator.cs
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Expand Up @@ -27,8 +27,8 @@ internal BsonDocument Translate(LambdaExpression lambdaExpression, VectorStoreRe
Debug.Assert(lambdaExpression.Parameters.Count == 1);
this._recordParameter = lambdaExpression.Parameters[0];

var preprocessor = new FilterTranslationPreprocessor { InlineCapturedVariables = true };
var preprocessedExpression = preprocessor.Visit(lambdaExpression.Body);
var preprocessor = new FilterTranslationPreprocessor { SupportsParameterization = false };
var preprocessedExpression = preprocessor.Preprocess(lambdaExpression.Body);

return this.Translate(preprocessedExpression);
}
Expand Down
4 changes: 2 additions & 2 deletions dotnet/src/Connectors/Connectors.Memory.Pinecone/PineconeFilterTranslator.cs
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Expand Up @@ -30,8 +30,8 @@ internal Metadata Translate(LambdaExpression lambdaExpression, VectorStoreRecord
Debug.Assert(lambdaExpression.Parameters.Count == 1);
this._recordParameter = lambdaExpression.Parameters[0];

var preprocessor = new FilterTranslationPreprocessor { InlineCapturedVariables = true };
var preprocessedExpression = preprocessor.Visit(lambdaExpression.Body);
var preprocessor = new FilterTranslationPreprocessor { SupportsParameterization = false };
var preprocessedExpression = preprocessor.Preprocess(lambdaExpression.Body);

return this.Translate(preprocessedExpression);
}
Expand Down
4 changes: 2 additions & 2 deletions dotnet/src/Connectors/Connectors.Memory.Qdrant/QdrantFilterTranslator.cs
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Expand Up @@ -27,8 +27,8 @@ internal Filter Translate(LambdaExpression lambdaExpression, VectorStoreRecordMo
Debug.Assert(lambdaExpression.Parameters.Count == 1);
this._recordParameter = lambdaExpression.Parameters[0];

var preprocessor = new FilterTranslationPreprocessor { InlineCapturedVariables = true };
var preprocessedExpression = preprocessor.Visit(lambdaExpression.Body);
var preprocessor = new FilterTranslationPreprocessor { SupportsParameterization = false };
var preprocessedExpression = preprocessor.Preprocess(lambdaExpression.Body);

return this.Translate(preprocessedExpression);
}
Expand Down
4 changes: 2 additions & 2 deletions dotnet/src/Connectors/Connectors.Memory.Redis/RedisFilterTranslator.cs
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Expand Up @@ -27,8 +27,8 @@ internal string Translate(LambdaExpression lambdaExpression, VectorStoreRecordMo
Debug.Assert(lambdaExpression.Parameters.Count == 1);
this._recordParameter = lambdaExpression.Parameters[0];

var preprocessor = new FilterTranslationPreprocessor { InlineCapturedVariables = true };
var preprocessedExpression = preprocessor.Visit(lambdaExpression.Body);
var preprocessor = new FilterTranslationPreprocessor { SupportsParameterization = false };
var preprocessedExpression = preprocessor.Preprocess(lambdaExpression.Body);

this.Translate(preprocessedExpression);
return this._filter.ToString();
Expand Down
4 changes: 2 additions & 2 deletions dotnet/src/Connectors/Connectors.Memory.Weaviate/WeaviateFilterTranslator.cs
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Expand Up @@ -29,8 +29,8 @@ internal string Translate(LambdaExpression lambdaExpression, VectorStoreRecordMo
Debug.Assert(lambdaExpression.Parameters.Count == 1);
this._recordParameter = lambdaExpression.Parameters[0];

var preprocessor = new FilterTranslationPreprocessor { InlineCapturedVariables = true };
var preprocessedExpression = preprocessor.Visit(lambdaExpression.Body);
var preprocessor = new FilterTranslationPreprocessor { SupportsParameterization = false };
var preprocessedExpression = preprocessor.Preprocess(lambdaExpression.Body);

this.Translate(preprocessedExpression);
return this._filter.ToString();
Expand Down
117 changes: 94 additions & 23 deletions ...nnectors/VectorData.Abstractions/ConnectorSupport/Filter/FilterTranslationPreprocessor.cs
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@@ -1,10 +1,9 @@
// Copyright (c) Microsoft. All rights reserved.

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq.Expressions;
using System.Reflection;
using System.Runtime.CompilerServices;

namespace Microsoft.Extensions.VectorData.ConnectorSupport.Filter;

Expand All @@ -15,40 +14,112 @@ namespace Microsoft.Extensions.VectorData.ConnectorSupport.Filter;
[Experimental("MEVD9001")]
public class FilterTranslationPreprocessor : ExpressionVisitor
{
private List<string>? _parameterNames;

/// <summary>
/// Whether to inline captured variables in the filter expression (when the database doesn't support parameters).
/// Whether the connector supports parameterization.
/// </summary>
public bool InlineCapturedVariables { get; init; }
/// <remarks>
/// If <see langword="false"/>, the visitor will inline captured variables and constant member accesses as simple constant nodes.
/// If <see langword="true"/>, these will instead be replaced with <see cref="QueryParameterExpression"/> nodes.
/// </remarks>
public required bool SupportsParameterization { get; init; }

/// <summary>
/// Whether to transform captured variables in the filter expression to <see cref="QueryParameterExpression"/> (when the database supports parameters).
/// Preprocesses the filter expression before translation.
/// </summary>
public bool TransformCapturedVariablesToQueryParameterExpressions { get; init; }
public Expression Preprocess(Expression node)
{
if (this.SupportsParameterization)
{
this._parameterNames = [];
}

return this.Visit(node);
}

/// <inheritdoc />
protected override Expression VisitMember(MemberExpression node)
{
// This identifies compiler-generated closure types which contain captured variables.
var visited = (MemberExpression)base.VisitMember(node);

// This identifies field and property access over constants, which can be evaluated immediately.
// This covers captured variables, since those are actually member accesses over compiled-generated closure types:
// var x = 8;
// _ = await collection.SearchAsync(vector, top: 3, new() { Filter = r => r.Int == x });
//
// This also covers member variables:
// _ = await collection.SearchAsync(vector, top: 3, new() { Filter = r => r.Int == this._x });
// ... as "this" here is represented by a ConstantExpression node in the tree.
//
// Some databases - mostly relational ones - support out-of-band parameters which can be referenced via placeholders
// from the query itself. For those databases, we transform the captured variable to QueryParameterExpression (this simplifies things for those
// from the query itself. For those databases, we transform the member access to QueryParameterExpression (this simplifies things for those
// connectors, and centralizes the pattern matching in a single centralized place).
// For databases which don't support parameters, we simply inline the captured variable as a constant in the tree, so that translators don't
// even need to be aware of the captured variable.
// For all other databases, we simply inline the captured variable as a constant in the tree.
if (node is MemberExpression { Expression: ConstantExpression constant, Member: FieldInfo fieldInfo }
&& constant.Type.Attributes.HasFlag(TypeAttributes.NestedPrivate)
&& Attribute.IsDefined(constant.Type, typeof(CompilerGeneratedAttribute), inherit: true))
// For databases which don't support parameters, we simply inline the evaluated member access as a constant in the tree, so that translators don't
// even need to be aware of it.

// Evaluate the MemberExpression to get the actual value, either for instance members (expression is a ConstantExpression) or for
// static members (expression is null).
object? baseValue;
switch (visited.Expression)
{
// Member access over constant (i.e. instance members)
case ConstantExpression { Value: var v }:
baseValue = v;
break;

// Member constant over null (i.e. static members)
case null:
baseValue = null;
break;

// Member constant over something that has already been parameterized (i.e. nested member access, e.g. r=> r.Int == this.SomeWrapper.Something)
case QueryParameterExpression p:
baseValue = p.Value;

// The previous parameter is getting replaced by the new one we're creating here, so remove its name from the list of parameter names.
this._parameterNames!.Remove(p.Name);
break;

default:
return visited;
}

object? evaluatedValue;

var memberInfo = visited.Member;

switch (memberInfo)
{
case FieldInfo fieldInfo:
evaluatedValue = fieldInfo.GetValue(baseValue);
break;
case PropertyInfo propertyInfo:
evaluatedValue = propertyInfo.GetValue(baseValue);
break;
default:
return visited;
}

// Inline the evaluated value (if the connector doesn't support parameterization, or if the field is readonly),
if (!this.SupportsParameterization)
{
return Expression.Constant(evaluatedValue, visited.Type);
}

// Otherwise, transform the node to a QueryParameterExpression which the connector will then translate to a parameter (e.g. SqlParameter).

// TODO: Share the same parameter when it references the same captured value

// Make sure parameter names are unique.
var origName = memberInfo.Name;
var name = origName;
for (var i = 0; this._parameterNames!.Contains(name); i++)
{
return (this.InlineCapturedVariables, this.TransformCapturedVariablesToQueryParameterExpressions) switch
{
(true, false) => Expression.Constant(fieldInfo.GetValue(constant.Value), node.Type),
(false, true) => new QueryParameterExpression(fieldInfo.Name, fieldInfo.GetValue(constant.Value), node.Type),

(true, true) => throw new InvalidOperationException("InlineCapturedVariables and TransformCapturedVariablesToQueryParameterExpressions cannot both be true."),
(false, false) => base.VisitMember(node)
};
name = $"{origName}_{i}";
}
this._parameterNames.Add(name);

return base.VisitMember(node);
return new QueryParameterExpression(name, evaluatedValue, visited.Type);
}
}
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