[Performance] EWMA SQL Query Plan Section

src/Microsoft.Health.Fhir.Core/Configs/CoreFeatureConfiguration.cs

@@ -106,5 +106,10 @@ public class CoreFeatureConfiguration
         /// SearchParameter cache synchronized across instances. Default is 1 minute if not specified.
         /// </summary>
         public int SearchParameterCacheRefreshIntervalMinutes { get; set; } = 1;
+
+        /// <summary>
+        /// Gets or sets the query configuration.
+        /// </summary>
+        public QueryConfiguration Query { get; set; } = new QueryConfiguration();
     }
 }

src/Microsoft.Health.Fhir.Core/Configs/OperationsConfiguration.cs

@@ -3,8 +3,6 @@
 // Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
 // -------------------------------------------------------------------------------------------------
 
-using Microsoft.Health.Fhir.Core.Features.Operations;
-
 namespace Microsoft.Health.Fhir.Core.Configs
 {
     public class OperationsConfiguration

src/Microsoft.Health.Fhir.Core/Configs/QueryConfiguration.cs

@@ -0,0 +1,15 @@
+// -------------------------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
+// -------------------------------------------------------------------------------------------------
+
+namespace Microsoft.Health.Fhir.Core.Configs
+{
+    public class QueryConfiguration
+    {
+        /// <summary>
+        /// If Dynamic Sql Query Plan Selection is enabled.
+        /// </summary>
+        public bool DynamicSqlQueryPlanSelectionEnabled { get; set; } = false;
+    }
+}

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/BinaryExpression.cs

@@ -76,6 +76,11 @@ string ValueToString()
             return $"(Field{BinaryOperator} {(ComponentIndex == null ? null : $"[{ComponentIndex}].")}{FieldName} {ValueToString()})";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            return $"(Field{BinaryOperator} {(ComponentIndex == null ? null : $"[{ComponentIndex}].")}{FieldName})";
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(BinaryExpression));

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/ChainedExpression.cs

@@ -83,6 +83,11 @@ public override string ToString()
             return $"({(Reversed ? "Reverse " : string.Empty)}Chain {ReferenceSearchParameter.Code}:{string.Join(", ", TargetResourceTypes)} {Expression})";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            return $"({(Reversed ? "Reverse " : string.Empty)}Chain {ReferenceSearchParameter.Code}:{string.Join(", ", TargetResourceTypes)} {Expression?.GetUniqueExpressionIdentifier()})";
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(ChainedExpression));

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/CompartmentSearchExpression.cs

@@ -57,6 +57,11 @@ public override string ToString()
             return $"(Compartment {CompartmentType} '{CompartmentId}')";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            return $"(Compartment {CompartmentType})";
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(CompartmentSearchExpression));

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/Expression.cs

@@ -5,6 +5,7 @@
 
 using System;
 using System.Collections.Generic;
+using Microsoft.Health.Core.Extensions;
 using Microsoft.Health.Fhir.Core.Models;
 
 namespace Microsoft.Health.Fhir.Core.Features.Search.Expressions
@@ -316,11 +317,21 @@ public static NotReferencedExpression NotReferenced()
             return new NotReferencedExpression();
         }
 
+        public string GetHashedUniqueExpressionIdentifier()
+        {
+            return GetUniqueExpressionIdentifier()?.ComputeHash();
+        }
+
         public abstract TOutput AcceptVisitor<TContext, TOutput>(IExpressionVisitor<TContext, TOutput> visitor, TContext context);
 
         /// <inheritdoc />
         public abstract override string ToString();
 
+        /// <summary>
+        /// Given an expression, returns its unique identifier, ignoring parameterizable values.
+        /// </summary>
+        public abstract string GetUniqueExpressionIdentifier();
+
         /// <summary>
         /// Accumulates a "value-insensitive" hash code of this instance, meaning it ignores parameterizable values.
         /// For example, date=2013&amp;name=Smith and date=2014&amp;name=Trudeau would have the same hash code.

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/InExpression.cs

@@ -50,6 +50,11 @@ public override string ToString()
             return $"({(ComponentIndex == null ? null : $"[{ComponentIndex}].")}{FieldName} IN ({string.Join(", ", Values)}))";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            return $"({(ComponentIndex == null ? null : $"[{ComponentIndex}].")}{FieldName})";
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(InExpression<T>));

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/IncludeExpression.cs

@@ -144,6 +144,11 @@ public override string ToString()
             return $"({reversed}Include{iterate}{wildcard}{paramName}{targetType})";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            return ToString();
+        }
+
         private IReadOnlyCollection<string> GetRequiredResources()
         {
             if (Reversed)

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/MissingFieldExpression.cs

@@ -42,6 +42,11 @@ public override string ToString()
             return $"(MissingField {(ComponentIndex == null ? null : $"[{ComponentIndex}].")}{FieldName})";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            return ToString();
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(MissingFieldException));

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/MissingSearchParameterExpression.cs

@@ -42,6 +42,11 @@ public override string ToString()
             return $"({(!IsMissing ? "Not" : null)}MissingParam {Parameter.Name})";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            return ToString();
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(MissingSearchParameterExpression));

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/MultiaryExpression.cs

@@ -52,6 +52,11 @@ public override string ToString()
             return $"({MultiaryOperation} {string.Join(' ', Expressions)})";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            return $"({MultiaryOperation} {string.Join(' ', Expressions.Select(e => e.GetUniqueExpressionIdentifier()))})";
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(MultiaryExpression));

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/NotExpression.cs

@@ -40,6 +40,11 @@ public override string ToString()
             return $"(Not {Expression})";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            return $"(Not {Expression?.GetUniqueExpressionIdentifier()})";
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(NotExpression));

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/NotReferencedExpression.cs

@@ -4,10 +4,6 @@
 // -------------------------------------------------------------------------------------------------
 
 using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 using EnsureThat;
 
 namespace Microsoft.Health.Fhir.Core.Features.Search.Expressions
@@ -30,6 +26,11 @@ public override string ToString()
             return "NotReferenced";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            return ToString();
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(NotReferencedExpression));

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/SearchParameterExpression.cs

@@ -35,6 +35,19 @@ public override string ToString()
             return $"(Param {Parameter.Code} {Expression})";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            // ResourceType is a special case where the expression requires the value to be included.
+            if (Parameter.Code == SearchParameterNames.ResourceType)
+            {
+                return $"(Param {Parameter.Code} {Expression})";
+            }
+            else
+            {
+                return $"(Param {Parameter.Code} {Expression?.GetUniqueExpressionIdentifier()})";
+            }
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(SearchParameterExpression));

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/SortExpression.cs

@@ -30,6 +30,11 @@ public override string ToString()
             return $"(Sort Param: {Parameter.Code})";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            return ToString();
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(SortExpression));

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/StringExpression.cs

@@ -63,6 +63,19 @@ public override string ToString()
             return $"(String{StringOperator}{(IgnoreCase ? "IgnoreCase" : null)} {(ComponentIndex == null ? null : $"[{ComponentIndex}].")}{FieldName} '{Value}')";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            // ReferenceResourceType is a special case where the expression requires the value to be included.
+            if (FieldName == FieldName.ReferenceResourceType)
+            {
+                return $"(String{StringOperator}{(IgnoreCase ? "IgnoreCase" : null)} {(ComponentIndex == null ? null : $"[{ComponentIndex}].")}{FieldName} '{Value}')";
+            }
+            else
+            {
+                return $"(String{StringOperator}{(IgnoreCase ? "IgnoreCase" : null)} {(ComponentIndex == null ? null : $"[{ComponentIndex}].")}{FieldName})";
+            }
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(StringExpression));

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/UnionExpression.cs

@@ -43,6 +43,11 @@ public override string ToString()
             return $"(Union ({Operator}) {Expressions} {string.Join(' ', Expressions)})";
         }
 
+        public override string GetUniqueExpressionIdentifier()
+        {
+            return $"(Union ({Operator}) {Expressions} {string.Join(' ', Expressions.Select(e => e.GetUniqueExpressionIdentifier()))})";
+        }
+
         public override void AddValueInsensitiveHashCode(ref HashCode hashCode)
         {
             hashCode.Add(typeof(UnionExpression));

src/Microsoft.Health.Fhir.Core/Microsoft.Health.Fhir.Core.csproj

@@ -29,7 +29,6 @@
     <EmbeddedResource Include="Data\OperationDefinition\bulk-update.json" />
     <EmbeddedResource Include="Data\OperationDefinition\bulk-delete-soft-deleted.json" />
     <EmbeddedResource Include="Data\OperationDefinition\includes.json" />
-    <EmbeddedResource Include="Data\OperationDefinition\docref.json" />
     <EmbeddedResource Include="Data\Stu3\search-parameters.json" />
     <EmbeddedResource Include="Data\Stu3\unsupported-search-parameters.json" />
     <EmbeddedResource Include="Data\Stu3\resourcepath-codesystem-mappings.json" />

src/Microsoft.Health.Fhir.Shared.Api/Registration/FhirServerServiceCollectionExtensions.cs

@@ -81,6 +81,7 @@ public static IFhirServerBuilder AddFhirServer(
             services.AddSingleton(Options.Options.Create(fhirServerConfiguration.Security));
             services.AddSingleton(Options.Options.Create(fhirServerConfiguration.Features));
             services.AddSingleton(Options.Options.Create(fhirServerConfiguration.CoreFeatures));
+            services.AddSingleton(Options.Options.Create(fhirServerConfiguration.CoreFeatures.Query));
             services.AddSingleton(Options.Options.Create(fhirServerConfiguration.Cors));
             services.AddSingleton(Options.Options.Create(fhirServerConfiguration.Operations));
             services.AddSingleton(Options.Options.Create(fhirServerConfiguration.Operations.Export));

src/Microsoft.Health.Fhir.Shared.Web/appsettings.json

@@ -36,7 +36,10 @@
                 "Default": "versioned",
                 "ResourceTypeOverrides": null
             },
-            "SearchParameterCacheRefreshIntervalMinutes": 1
+            "SearchParameterCacheRefreshIntervalMinutes": 1,
+            "Query": {
+                "DynamicSqlQueryPlanSelectionEnabled": false
+            }
         },
         "CosmosDb": {
             "CollectionId": null,

src/Microsoft.Health.Fhir.SqlServer.UnitTests/Features/Search/Expressions/ExpressionTestUtilities.cs

@@ -0,0 +1,21 @@
+// -------------------------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
+// -------------------------------------------------------------------------------------------------
+
+using Microsoft.Health.Fhir.Core.Features.Search.Expressions;
+using Xunit;
+
+namespace Microsoft.Health.Fhir.SqlServer.UnitTests.Features.Search.Expressions
+{
+    public sealed class ExpressionTestUtilities
+    {
+        internal static void ValidateUniqueExpressionIdentifier(Expression expression)
+        {
+            var identifier = expression.GetUniqueExpressionIdentifier();
+            var hash = expression.GetHashedUniqueExpressionIdentifier();
+            Assert.NotEqual(identifier, hash);
+            Assert.Equal(64, hash.Length);
+        }
+    }
+}

src/Microsoft.Health.Fhir.SqlServer.UnitTests/Features/Search/Expressions/FlatteningRewriterTests.cs

@@ -20,7 +20,10 @@ public void GivenAMultiaryExpressionWithASingleElement_WhenFlattened_RemovesTheM
         {
             MultiaryExpression inputExpression = Expression.And(Expression.Equals(FieldName.Number, null, 1));
             Expression visitedExpression = inputExpression.AcceptVisitor(FlatteningRewriter.Instance);
+
             Assert.Equal("(FieldEqual Number 1)", visitedExpression.ToString());
+
+            ExpressionTestUtilities.ValidateUniqueExpressionIdentifier(visitedExpression);
         }
 
         [Fact]
@@ -33,6 +36,8 @@ public void GivenTwoLayersOfAndExpressions_WhenFlattened_CombinesToOneAndExpress
 
             Expression visitedExpression = inputExpression.AcceptVisitor(FlatteningRewriter.Instance);
             Assert.Equal("(And (FieldGreaterThan Number 1) (FieldLessThan Number 5) (FieldGreaterThan Quantity 1) (FieldLessThan Quantity 5))", visitedExpression.ToString());
+
+            ExpressionTestUtilities.ValidateUniqueExpressionIdentifier(visitedExpression);
         }
 
         [Fact]
@@ -45,6 +50,8 @@ public void GivenTwoLayersOfOrExpressions_WhenFlattened_CombinesToOneOrExpressio
 
             Expression visitedExpression = inputExpression.AcceptVisitor(FlatteningRewriter.Instance);
             Assert.Equal("(Or (FieldGreaterThan Number 1) (FieldLessThan Number 5) (FieldGreaterThan Quantity 1) (FieldLessThan Quantity 5))", visitedExpression.ToString());
+
+            ExpressionTestUtilities.ValidateUniqueExpressionIdentifier(visitedExpression);
         }
 
         [Fact]
@@ -57,6 +64,8 @@ public void GivenAnOrExpressionWithAnAndChild_WhenFlattened_RemainsTheSame()
 
             Expression visitedExpression = inputExpression.AcceptVisitor(FlatteningRewriter.Instance);
             Assert.Equal("(Or (And (FieldGreaterThan Number 1) (FieldLessThan Number 5)) (And (FieldGreaterThan Quantity 1) (FieldLessThan Quantity 5)))", visitedExpression.ToString());
+
+            ExpressionTestUtilities.ValidateUniqueExpressionIdentifier(visitedExpression);
         }
     }
 }