Move to using log_end_lsn from sys.dm_db_log_stats

readme.md

@@ -26,10 +26,7 @@ Effectively consumers will always receive the most current data, while the load
 ## Assumptions
 
  * Frequency of updates to data is relatively low compared to reads
- * Using SQL Server or Postgres timestamp features
-    * SQL Server: Using either [SQL Server Change Tracking](https://learn.microsoft.com/en-us/sql/relational-databases/track-changes/track-data-changes-sql-server) and/or [SQL Server Row Versioning](https://learn.microsoft.com/en-us/sql/t-sql/data-types/rowversion-transact-sql)
-    * Postgres: [track_commit_timestamp](https://www.postgresql.org/docs/17/runtime-config-replication.html#GUC-TRACK-COMMIT-TIMESTAMP) is enabled. This can be done using `ALTER SYSTEM SET track_commit_timestamp to "on"` and then restarting the Postgres service
-
+ * Using SQL Server or Postgres. Postgres required [track_commit_timestamp](https://www.postgresql.org/docs/17/runtime-config-replication.html#GUC-TRACK-COMMIT-TIMESTAMP) to be enabled. This can be done using `ALTER SYSTEM SET track_commit_timestamp to "on"` and then restarting the Postgres service
 
 
 ## 304 Not Modified Flow
@@ -72,21 +69,12 @@ AssemblyWriteTime = File.GetLastWriteTime(webAssemblyLocation).Ticks.ToString();
 
 #### SQL timestamp
 
-A combination of [change_tracking_current_version](https://learn.microsoft.com/en-us/sql/relational-databases/system-functions/change-tracking-current-version-transact-sql) (if tracking is enabled) and [@@DBTS (row version timestamp)](https://learn.microsoft.com/en-us/sql/t-sql/functions/dbts-transact-sql)
-
-
 <!-- snippet: SqlServerTimestamp -->
 <a id='snippet-SqlServerTimestamp'></a>
 ```cs
-declare @changeTracking bigint = change_tracking_current_version();
-declare @timeStamp bigint = convert(bigint, @@dbts);
-
-if (@changeTracking is null)
-  select cast(@timeStamp as varchar)
-else
-  select cast(@timeStamp as varchar) + '-' + cast(@changeTracking as varchar)
+select log_end_lsn from sys.dm_db_log_stats(db_id())
 ```
-<sup><a href='/src/Delta/DeltaExtensions_Sql.cs#L46-L54' title='Snippet source file'>snippet source</a> | <a href='#snippet-SqlServerTimestamp' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/Delta/DeltaExtensions_Sql.cs#L46-L48' title='Snippet source file'>snippet source</a> | <a href='#snippet-SqlServerTimestamp' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 
@@ -138,8 +126,6 @@ Only one of the above should be used.
 
 ### SQL Server DB Schema
 
-Ensure [SQL Server Change Tracking](https://learn.microsoft.com/en-us/sql/relational-databases/track-changes/track-data-changes-sql-server) and/or [SQL Server Row Versioning](https://learn.microsoft.com/en-us/sql/t-sql/data-types/rowversion-transact-sql) is enabled for all relevant tables.
-
 Example SQL schema:
 
 <!-- snippet: Usage.Schema.verified.sql -->
@@ -331,25 +317,25 @@ var application = webApplicationBuilder.Build();
 application.UseDelta(
     getConnection: httpContext => httpContext.RequestServices.GetRequiredService<SqlConnection>());
 ```
-<sup><a href='/src/DeltaTests/Usage.cs#L220-L226' title='Snippet source file'>snippet source</a> | <a href='#snippet-CustomDiscoveryConnection' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/DeltaTests/Usage.cs#L303-L309' title='Snippet source file'>snippet source</a> | <a href='#snippet-CustomDiscoveryConnection' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 To use custom connection and transaction discovery:
 
 <!-- snippet: CustomDiscoveryConnectionAndTransaction -->
 <a id='snippet-CustomDiscoveryConnectionAndTransaction'></a>
 ```cs
-var webApplication = webApplicationBuilder.Build();
-webApplication.UseDelta(
+var application = webApplicationBuilder.Build();
+application.UseDelta(
     getConnection: httpContext =>
     {
         var provider = httpContext.RequestServices;
-        var sqlConnection = provider.GetRequiredService<SqlConnection>();
-        var sqlTransaction = provider.GetService<SqlTransaction>();
-        return new(sqlConnection, sqlTransaction);
+        var connection = provider.GetRequiredService<SqlConnection>();
+        var transaction = provider.GetService<SqlTransaction>();
+        return new(connection, transaction);
     });
 ```
-<sup><a href='/src/DeltaTests/Usage.cs#L231-L243' title='Snippet source file'>snippet source</a> | <a href='#snippet-CustomDiscoveryConnectionAndTransaction' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/DeltaTests/Usage.cs#L314-L326' title='Snippet source file'>snippet source</a> | <a href='#snippet-CustomDiscoveryConnectionAndTransaction' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 
@@ -536,7 +522,7 @@ Nuget: [Delta.SqlServer](https://www.nuget.org/packages/Delta.SqlServer)
 ```cs
 var timeStamp = await sqlConnection.GetLastTimeStamp();
 ```
-<sup><a href='/src/DeltaTests/Usage.cs#L59-L63' title='Snippet source file'>snippet source</a> | <a href='#snippet-GetLastTimeStampSqlConnection' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/DeltaTests/Usage.cs#L165-L169' title='Snippet source file'>snippet source</a> | <a href='#snippet-GetLastTimeStampSqlConnection' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 
@@ -564,7 +550,7 @@ foreach (var db in trackedDatabases)
     Trace.WriteLine(db);
 }
 ```
-<sup><a href='/src/DeltaTests/Usage.cs#L118-L126' title='Snippet source file'>snippet source</a> | <a href='#snippet-GetDatabasesWithTracking' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/DeltaTests/Usage.cs#L201-L209' title='Snippet source file'>snippet source</a> | <a href='#snippet-GetDatabasesWithTracking' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 Uses the following SQL:
@@ -594,7 +580,7 @@ foreach (var db in trackedTables)
     Trace.WriteLine(db);
 }
 ```
-<sup><a href='/src/DeltaTests/Usage.cs#L144-L152' title='Snippet source file'>snippet source</a> | <a href='#snippet-GetTrackedTables' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/DeltaTests/Usage.cs#L227-L235' title='Snippet source file'>snippet source</a> | <a href='#snippet-GetTrackedTables' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 Uses the following SQL:
@@ -619,7 +605,7 @@ Determine if change tracking is enabled for a database.
 ```cs
 var isTrackingEnabled = await sqlConnection.IsTrackingEnabled();
 ```
-<sup><a href='/src/DeltaTests/Usage.cs#L209-L213' title='Snippet source file'>snippet source</a> | <a href='#snippet-IsTrackingEnabled' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/DeltaTests/Usage.cs#L292-L296' title='Snippet source file'>snippet source</a> | <a href='#snippet-IsTrackingEnabled' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 Uses the following SQL:
@@ -646,7 +632,7 @@ Enable change tracking for a database.
 ```cs
 await sqlConnection.EnableTracking();
 ```
-<sup><a href='/src/DeltaTests/Usage.cs#L203-L207' title='Snippet source file'>snippet source</a> | <a href='#snippet-EnableTracking' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/DeltaTests/Usage.cs#L286-L290' title='Snippet source file'>snippet source</a> | <a href='#snippet-EnableTracking' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 Uses the following SQL:
@@ -674,7 +660,7 @@ Disable change tracking for a database and all tables within that database.
 ```cs
 await sqlConnection.DisableTracking();
 ```
-<sup><a href='/src/DeltaTests/Usage.cs#L188-L192' title='Snippet source file'>snippet source</a> | <a href='#snippet-DisableTracking' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/DeltaTests/Usage.cs#L271-L275' title='Snippet source file'>snippet source</a> | <a href='#snippet-DisableTracking' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 Uses the following SQL:
@@ -711,7 +697,7 @@ Enables change tracking for all tables listed, and disables change tracking for
 ```cs
 await sqlConnection.SetTrackedTables(["Companies"]);
 ```
-<sup><a href='/src/DeltaTests/Usage.cs#L138-L142' title='Snippet source file'>snippet source</a> | <a href='#snippet-SetTrackedTables' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/DeltaTests/Usage.cs#L221-L225' title='Snippet source file'>snippet source</a> | <a href='#snippet-SetTrackedTables' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 Uses the following SQL:
@@ -785,7 +771,6 @@ If disable cache is checked, the browser will not send the `if-none-match` heade
 Chromium, and hence the Chrome and Edge browsers, are very sensitive to certificate problems when determining if an item should be cached. Specifically, if a request is done dynamically (type: xhr) and the server is using a self-signed certificate, then the browser will not send the `if-none-match` header. [Reference]( https://issues.chromium.org/issues/40666473). If self-signed certificates are required during development in lower environment, then use FireFox to test the caching behavior. 
 
 
-
 ## Programmatic client usage
 
 Delta is primarily designed to support web browsers as a client. All web browsers have the necessary 304 and caching functionally required.

readme.source.md

@@ -19,10 +19,7 @@ Effectively consumers will always receive the most current data, while the load
 ## Assumptions
 
  * Frequency of updates to data is relatively low compared to reads
- * Using SQL Server or Postgres timestamp features
-    * SQL Server: Using either [SQL Server Change Tracking](https://learn.microsoft.com/en-us/sql/relational-databases/track-changes/track-data-changes-sql-server) and/or [SQL Server Row Versioning](https://learn.microsoft.com/en-us/sql/t-sql/data-types/rowversion-transact-sql)
-    * Postgres: [track_commit_timestamp](https://www.postgresql.org/docs/17/runtime-config-replication.html#GUC-TRACK-COMMIT-TIMESTAMP) is enabled. This can be done using `ALTER SYSTEM SET track_commit_timestamp to "on"` and then restarting the Postgres service
-
+ * Using SQL Server or Postgres. Postgres required [track_commit_timestamp](https://www.postgresql.org/docs/17/runtime-config-replication.html#GUC-TRACK-COMMIT-TIMESTAMP) to be enabled. This can be done using `ALTER SYSTEM SET track_commit_timestamp to "on"` and then restarting the Postgres service
 
 
 ## 304 Not Modified Flow
@@ -58,9 +55,6 @@ snippet: AssemblyWriteTime
 
 #### SQL timestamp
 
-A combination of [change_tracking_current_version](https://learn.microsoft.com/en-us/sql/relational-databases/system-functions/change-tracking-current-version-transact-sql) (if tracking is enabled) and [@@DBTS (row version timestamp)](https://learn.microsoft.com/en-us/sql/t-sql/functions/dbts-transact-sql)
-
-
 snippet: SqlServerTimestamp
 
 
@@ -91,8 +85,6 @@ Only one of the above should be used.
 
 ### SQL Server DB Schema
 
-Ensure [SQL Server Change Tracking](https://learn.microsoft.com/en-us/sql/relational-databases/track-changes/track-data-changes-sql-server) and/or [SQL Server Row Versioning](https://learn.microsoft.com/en-us/sql/t-sql/data-types/rowversion-transact-sql) is enabled for all relevant tables.
-
 Example SQL schema:
 
 snippet: Usage.Schema.verified.sql
@@ -343,7 +335,6 @@ If disable cache is checked, the browser will not send the `if-none-match` heade
 Chromium, and hence the Chrome and Edge browsers, are very sensitive to certificate problems when determining if an item should be cached. Specifically, if a request is done dynamically (type: xhr) and the server is using a self-signed certificate, then the browser will not send the `if-none-match` header. [Reference]( https://issues.chromium.org/issues/40666473). If self-signed certificates are required during development in lower environment, then use FireFox to test the caching behavior. 
 
 
-
 ## Programmatic client usage
 
 Delta is primarily designed to support web browsers as a client. All web browsers have the necessary 304 and caching functionally required.

src/Delta.EFTests/LocalDbTestBase.cs

@@ -12,11 +12,8 @@ static LocalDbTestBase() =>
             },
             storage: Storage.FromSuffix<SampleDbContext>("ef"));
 
-    public Task<SqlDatabase<SampleDbContext>> LocalDb(string? testSuffix = null)
-        => sqlInstance.Build(testFile, null, GetName(testSuffix));
-
-    public Task<SampleDbContext> LocalDbContext(string? testSuffix = null)
-        => sqlInstance.BuildContext(testFile, null, GetName(testSuffix));
+    public Task<SqlDatabase<SampleDbContext>> LocalDb(string? testSuffix = null) =>
+        sqlInstance.Build(testFile, null, GetName(testSuffix));
 
     static string GetName(string? testSuffix)
     {

src/Delta.EFTests/Usage.cs

@@ -43,41 +43,16 @@ public async Task GetLastTimeStamp()
     }
 
     [Test]
-    public async Task LastTimeStampRowVersion()
+    public async Task LastTimeStamp()
     {
         await using var database = await LocalDb();
-
-        var context = database.Context;
-        var emptyTimeStamp = await context.GetLastTimeStamp();
-        IsNotEmpty(emptyTimeStamp);
-        IsNotNull(emptyTimeStamp);
-
-        var entity = new Company
-        {
-            Content = "The company"
-        };
-        await database.AddData(entity);
-        var addTimeStamp = await context.GetLastTimeStamp();
-        IsNotEmpty(addTimeStamp);
-        IsNotNull(addTimeStamp);
-        AreNotEqual(addTimeStamp, emptyTimeStamp);
-
-        entity.Content = "The company2";
-        await context.SaveChangesAsync();
-        var updateTimeStamp = await context.GetLastTimeStamp();
-        IsNotEmpty(updateTimeStamp);
-        IsNotNull(updateTimeStamp);
-        AreNotEqual(updateTimeStamp, addTimeStamp);
-        AreNotEqual(updateTimeStamp, emptyTimeStamp);
-    }
-
-    [Test]
-    public async Task LastTimeStampRowVersionAndTracking()
-    {
-        await using var database = await LocalDb();
-
-        await database.Connection.EnableTracking();
         var context = database.Context;
+        //seed with an entity so there is something in transaction log
+        await database.AddData(
+            new Company
+            {
+                Content = "The company"
+            });
         var emptyTimeStamp = await context.GetLastTimeStamp();
         IsNotEmpty(emptyTimeStamp);
         IsNotNull(emptyTimeStamp);
@@ -99,6 +74,5 @@ public async Task LastTimeStampRowVersionAndTracking()
         IsNotNull(updateTimeStamp);
         AreNotEqual(updateTimeStamp, addTimeStamp);
         AreNotEqual(updateTimeStamp, emptyTimeStamp);
-
     }
 }

src/Delta/DeltaExtensions_Sql.cs

@@ -42,18 +42,20 @@ static async Task<string> ExecuteTimestampQuery(DbCommand command, Cancel cancel
         var name = command.GetType().Name;
         if (name == "SqlCommand")
         {
-            command.CommandText = @"
+            command.CommandText = $@"
 -- begin-snippet: SqlServerTimestamp
-declare @changeTracking bigint = change_tracking_current_version();
-declare @timeStamp bigint = convert(bigint, @@dbts);
-
-if (@changeTracking is null)
-  select cast(@timeStamp as varchar)
-else
-  select cast(@timeStamp as varchar) + '-' + cast(@changeTracking as varchar)
+select log_end_lsn from sys.dm_db_log_stats(db_id())
 -- end-snippet
 ";
-            return (string) (await command.ExecuteScalarAsync(cancel))!;
+            await using var reader = await command.ExecuteReaderAsync(CommandBehavior.SingleRow, cancel);
+            var readAsync = await reader.ReadAsync(cancel);
+            // for empty transaction log
+            if(!readAsync)
+            {
+                return string.Empty;
+            }
+
+            return (string)reader[0];
         }
 
         if (name == "NpgsqlCommand")

src/DeltaTests/LocalDbTestBase.cs

@@ -3,10 +3,20 @@ public abstract class LocalDbTestBase
 {
     static SqlInstance sqlInstance = new(
         name: "DeltaTests",
-        buildTemplate: DbBuilder.Create);
+        buildTemplate: async connection =>
+        {
+            await  DbBuilder.Create(connection);
+            await using var command = connection.CreateCommand();
+            command.CommandText =
+                $"""
+                 insert into [Companies] (Id, Content)
+                 values ('{Guid.NewGuid()}', 'initial data')
+                 """;
+            await command.ExecuteNonQueryAsync();
+        });
 
-    public Task<SqlDatabase> LocalDb(string? testSuffix = null)
-        => sqlInstance.Build(testFile, null, GetName(testSuffix));
+    public Task<SqlDatabase> LocalDb(string? testSuffix = null) =>
+        sqlInstance.Build(testFile, null, GetName(testSuffix));
 
     static string GetName(string? testSuffix)
     {

src/DeltaTests/ModuleInitializer.cs

@@ -8,6 +8,7 @@ public static void Init()
         DeltaExtensions.UseResponseDiagnostics = true;
 
         #endregion
+
         VerifierSettings.InitializePlugins();
     }
 }