Revert "opt out for identity map optimizations of inline aggregates"

This reverts commit b568270.

docs/scenarios/command_handler_workflow.md

@@ -133,38 +133,6 @@ the standard `IDocumentSession.SaveChangesAsync()` method call. At that point, i
 `Order` stream between our handler calling `FetchForWriting()` and `IDocumentSession.SaveChangesAsync()`, the entire command will fail with a Marten
 `ConcurrencyException`.
 
-## Inline Aggregates <Badge type="tip" text="7.22" />
-
-::: warning
-You may need to opt out of this behavior if you are modifying the aggregate document returned by `FetchForWriting`
-before new events are applied to it to not arrive at incorrectly applied projection data. 
-:::
-
-`FetchForWriting()` works with all possible projection lifecycles as of Marten 7. However, there's a wrinkle with `Inline`
-projections you should be aware of. It's frequently a valuable optimization to use _Lightweight_ sessions that omit
-the identity map behavior. Let's say that we have a configuration like this:
-
-snippet: sample_using_lightweight_sessions_with_inline_single_stream_projection
-
-As an optimization, Marten is quietly turning on the identity map behavior for just a single aggregate document type
-when `FetchForWriting()` is called with an `Inline` projection as shown below:
-
-snippet: sample_usage_of_identity_map_for_inline_projections
-
-This was done specifically to prevent unnecessary database fetches for the exact same data within common command handler
-workflow operations. There can of course be a downside if you happen to be making any kind of mutations to the aggregate
-document somewhere in between calling `FetchForWriting()` and `SaveChangesAsync()`, so to opt out of this behavior if 
-that causes you any trouble, use this:
-
-
-::: info
-Marten's default behavior of using sessions with the _Identity Map_ functionality option turned on was admittedly copied
-from RavenDb almost a decade ago, and the Marten team has been too afraid to change the default behavior to the more performant, _Lightweight_ sessions because of the 
-very real risk of introducing difficult to diagnose regression errors. There you go folks, a 10 year old decision that this 
-author still regrets, but we're probably stuck with for the foreseeable future.
-:::
-
-
 ## Explicit Optimistic Concurrency
 
 This time let's explicitly opt into optimistic concurrency checks by telling Marten what the expected starting

src/EventSourcingTests/Aggregation/fetching_inline_aggregates_for_writing.cs

@@ -1,103 +1,17 @@
 using System;
 using System.Threading.Tasks;
-using Marten;
 using Marten.Events;
 using Marten.Events.Projections;
 using Marten.Exceptions;
 using Marten.Storage;
 using Marten.Testing.Harness;
-using Microsoft.Extensions.Configuration;
-using Microsoft.Extensions.Hosting;
 using Xunit;
 using Shouldly;
 
 namespace EventSourcingTests.Aggregation;
 
 public class fetching_inline_aggregates_for_writing : OneOffConfigurationsContext
 {
-    public static async Task example()
-    {
-
-
-        #region sample_using_lightweight_sessions_with_inline_single_stream_projection
-
-        var builder = Host.CreateApplicationBuilder();
-        builder.Services.AddMarten(opts =>
-            {
-                opts.Connection(builder.Configuration.GetConnectionString("postgres"));
-
-                // An inline single stream projection that builds SimpleAggregate
-                // A "snapshot" in Marten still boils down to a SingleStreamProjection<T>
-                // for that "T" in Marten internals
-                opts.Projections.Snapshot<SimpleAggregate>(SnapshotLifecycle.Inline);
-            })
-
-            // This is a commonly used, frequently helpful performance optimization
-            .UseLightweightSessions();
-
-        using var host = builder.Build();
-        await host.StartAsync();
-
-        #endregion
-
-        #region sample_usage_of_identity_map_for_inline_projections
-
-        // Little helper extension method to quickly get at the Marten
-        // DocumentStore from an IHost
-        var store = host.DocumentStore();
-
-        // This session is *not* using identity map by default as
-        // a performance optimization
-        using var session = store.LightweightSession();
-
-        // Some aggregate id that would probably be passed in through a CQRS command message
-        // or maybe an HTTP request argument
-        var id = Guid.NewGuid();
-
-        // In your command handler, you would use this call to fetch both the current state
-        // of the SimpleAggregate as well as getting Marten ready to do optimistic concurrency
-        // checks for you as well
-        var stream = await session.Events.FetchForWriting<SimpleAggregate>(id);
-
-        // Just showing you that this is the current version of the projected
-        // aggregate document that was fetched out of the database by Marten
-        var aggregate = stream.Aggregate;
-
-        // The command would append new events to the event stream...
-        stream.AppendMany(new AEvent(), new BEvent());
-
-        // Persist the new events to the existing event stream, and oh, yeah,
-        // also update the SimpleAggregate document with the new events
-        // As of Marten 7.21, Marten is able to start with the version of the aggregate
-        // document that was initially loaded as part of FetchForWriting() instead
-        // of having to fetch it all over again from the database
-        await session.SaveChangesAsync();
-
-        #endregion
-    }
-
-    public static async Task disable_optimization()
-    {
-        var builder = Host.CreateApplicationBuilder();
-        builder.Services.AddMarten(opts =>
-            {
-                opts.Connection(builder.Configuration.GetConnectionString("postgres"));
-
-                // An inline single stream projection that builds SimpleAggregate
-                // A "snapshot" in Marten still boils down to a SingleStreamProjection<T>
-                // for that "T" in Marten internals
-                opts.Projections.Snapshot<SimpleAggregate>(SnapshotLifecycle.Inline);
-
-                opts.Events.UseIdentityMapForInlineAggregates = false;
-            })
-
-            // This is a commonly used, frequently helpful performance optimization
-            .UseLightweightSessions();
-
-        using var host = builder.Build();
-        await host.StartAsync();
-    }
-
     [Fact]
     public async Task fetch_new_stream_for_writing_Guid_identifier()
     {

src/EventSourcingTests/EventGraphTests.cs

@@ -106,12 +106,6 @@ public void switch_to_quick_and_back_to_rich()
         theGraph.EventAppender.ShouldBeOfType<RichEventAppender>();
     }
 
-    [Fact]
-    public void use_identity_map_optimization_is_true_by_default()
-    {
-        theGraph.UseIdentityMapForInlineAggregates.ShouldBeTrue();
-    }
-
     public class HouseRemodeling
     {
         public Guid Id { get; set; }

src/Marten/Events/EventGraph.cs

@@ -73,14 +73,6 @@ internal EventGraph(StoreOptions options)
 
     internal EventMetadataCollection Metadata { get; } = new();
 
-    /// <summary>
-    /// Setting this to true will direct Marten to automatically use the identity map for inline projections
-    /// in calls to FetchForWriting as an optimization to reduce repeated queries for the same aggregate.
-    /// The default is true. Disable this call if applying state changes to the loaded aggregate in your own
-    /// command handlers
-    /// </summary>
-    public bool UseIdentityMapForInlineAggregates { get; set; } = true;
-
     /// <summary>
     /// TimeProvider used for event timestamping metadata. Replace for controlling the timestamps
     /// in testing

src/Marten/Events/Fetching/FetchInlinedPlan.cs

@@ -29,12 +29,9 @@ public async Task<IEventStream<TDoc>> FetchForWriting(DocumentSessionBase sessio
         await _identityStrategy.EnsureEventStorageExists<TDoc>(session, cancellation).ConfigureAwait(false);
         await session.Database.EnsureStorageExistsAsync(typeof(TDoc), cancellation).ConfigureAwait(false);
 
-        if (session.Options.Events.UseIdentityMapForInlineAggregates)
-        {
-            // Opt into the identity map mechanics for this aggregate type just in case
-            // you're using a lightweight session
-            session.UseIdentityMapFor<TDoc>();
-        }
+        // Opt into the identity map mechanics for this aggregate type just in case
+        // you're using a lightweight session
+        session.UseIdentityMapFor<TDoc>();
 
         if (forUpdate)
         {

src/Marten/Events/IEventStoreOptions.cs

@@ -53,14 +53,6 @@ public interface IEventStoreOptions
 
         public EventAppendMode AppendMode { get; set; }
 
-        /// <summary>
-        /// Setting this to true will direct Marten to automatically use the identity map for inline projections
-        /// in calls to FetchForWriting as an optimization to reduce repeated queries for the same aggregate.
-        /// The default is true. Disable this call if applying state changes to the loaded aggregate in your own
-        /// command handlers
-        /// </summary>
-        public bool UseIdentityMapForInlineAggregates { get; set; }
-
         /// <summary>
         ///     Register an event type with Marten. This isn't strictly necessary for normal usage,
         ///     but can help Marten with asynchronous projections where Marten hasn't yet encountered