fix: enable altering hypertable dimensions via AlterHypertableOperation

  This commit fixes issue #14 where changes to hypertable dimensions were not being detected or applied during migrations.

  Changes:
  - Add AdditionalDimensions and OldAdditionalDimensions properties to AlterHypertableOperation
  - Implement dimension comparison logic in HypertableDiffer.AreDimensionsEqual()
  - Update HypertableOperationGenerator to generate add_dimension() SQL for new dimensions
  - Add warning comment when dimensions are removed (TimescaleDB limitation)
  - Fix minor whitespace formatting issues in test files

  Technical details:
  - Only new dimensions generate SQL in Up() migrations
  - Removed dimensions generate warning comments in Down() migrations (cannot be reversed)
  - Dimension comparison checks ColumnName, Type, Interval, and NumberOfPartitions

Author: sebastian-ederer

CmdScale.EntityFrameworkCore.TimescaleDB.Tests/Generators/HypertableOperationGeneratorTests.cs

@@ -14,7 +14,7 @@ public class HypertableOperationGeneratorTests
         private static string GetGeneratedCode(dynamic operation)
         {
             IndentedStringBuilder builder = new();
-            
+
             HypertableOperationGenerator generator = new(true);
             List<string> statements = generator.Generate(operation);
             SqlBuilderHelper.BuildQueryString(statements, builder);

CmdScale.EntityFrameworkCore.TimescaleDB.Tests/Generators/ReorderPolicyOperationGeneratorTests.cs

@@ -53,9 +53,9 @@ public void Generate_Add_with_non_default_schedule_creates_add_and_alter_sql()
                 IndexName = "IX_TestTable_Time",
                 InitialStart = testDate,
                 ScheduleInterval = "2 days",
-                MaxRuntime = "1 hour",    
-                MaxRetries = 5,             
-                RetryPeriod = "10 minutes"  
+                MaxRuntime = "1 hour",
+                MaxRetries = 5,
+                RetryPeriod = "10 minutes"
             };
 
             string expected = @".Sql(@""
@@ -78,10 +78,10 @@ FROM timescaledb_information.jobs
         public void Generate_Drop_creates_correct_remove_policy_sql()
         {
             // Arrange
-            DropReorderPolicyOperation operation = new() 
-            { 
+            DropReorderPolicyOperation operation = new()
+            {
                 Schema = "public",
-                TableName = "TestTable" 
+                TableName = "TestTable"
             };
 
             string expected = @".Sql(@""

CmdScale.EntityFrameworkCore.TimescaleDB/Configuration/ContinuousAggregate/ContinuousAggregateTypeBuilder.cs

@@ -98,8 +98,8 @@ EAggregateFunction function
 
         public static ContinuousAggregateBuilder<TEntity, TSourceEntity> AddGroupByColumn<TEntity, TSourceEntity, TProperty>(
             this ContinuousAggregateBuilder<TEntity, TSourceEntity> builder,
-            Expression<Func<TSourceEntity, TProperty>> propertyExpression) 
-            where TEntity : class 
+            Expression<Func<TSourceEntity, TProperty>> propertyExpression)
+            where TEntity : class
             where TSourceEntity : class
         {
             string propertyName = GetPropertyName(propertyExpression);

CmdScale.EntityFrameworkCore.TimescaleDB/Configuration/Hypertable/HypertableAnnotations.cs

@@ -8,7 +8,7 @@ public static class HypertableAnnotations
         public const string IsHypertable = "TimescaleDB:IsHypertable";
         public const string HypertableTimeColumn = "TimescaleDB:TimeColumnName";
         public const string EnableCompression = "TimescaleDB:EnableCompression";
-        public const string ChunkTimeInterval ="TimescaleDB:ChunkTimeInterval";
+        public const string ChunkTimeInterval = "TimescaleDB:ChunkTimeInterval";
         public const string ChunkSkipColumns = "TimescaleDB:ChunkSkipColumns";
         public const string AdditionalDimensions = "TimescaleDB:AdditionalDimensions";
     }

CmdScale.EntityFrameworkCore.TimescaleDB/Generators/HypertableOperationGenerator.cs

@@ -139,6 +139,47 @@ public List<string> Generate(AlterHypertableOperation operation)
                 }
             }
 
+            // Handle AdditionalDimensions - only add new dimensions
+            // NOTE: TimescaleDB does NOT support removing dimensions from hypertables.
+            // Once a dimension is added, it cannot be removed. Therefore, we only generate
+            // SQL for adding new dimensions and ignore dimension removals.
+            IReadOnlyList<Dimension> newDimensions = operation.AdditionalDimensions ?? [];
+            IReadOnlyList<Dimension> oldDimensions = operation.OldAdditionalDimensions ?? [];
+
+            // Find dimensions that are in new but not in old (added dimensions)
+            foreach (Dimension newDim in newDimensions)
+            {
+                bool exists = oldDimensions.Any(oldDim =>
+                    oldDim.ColumnName == newDim.ColumnName &&
+                    oldDim.Type == newDim.Type &&
+                    oldDim.Interval == newDim.Interval &&
+                    oldDim.NumberOfPartitions == newDim.NumberOfPartitions);
+
+                if (!exists)
+                {
+                    if (newDim.Type == EDimensionType.Range)
+                    {
+                        statements.Add($"SELECT add_dimension({qualifiedTableName}, by_range('{newDim.ColumnName}', INTERVAL '{newDim.Interval}'));");
+                    }
+                    else if (newDim.Type == EDimensionType.Hash)
+                    {
+                        statements.Add($"SELECT add_dimension({qualifiedTableName}, by_hash('{newDim.ColumnName}', {newDim.NumberOfPartitions}));");
+                    }
+                }
+            }
+
+            // Warn if dimensions were removed (which cannot be reversed in TimescaleDB)
+            List<Dimension> removedDimensions = [.. oldDimensions
+                .Where(oldDim => !newDimensions.Any(newDim =>
+                    oldDim.ColumnName == newDim.ColumnName &&
+                    oldDim.Type == newDim.Type))];
+
+            if (removedDimensions.Count > 0)
+            {
+                string dimensionList = string.Join(", ", removedDimensions.Select(d => $"'{d.ColumnName}'"));
+                statements.Add($"-- WARNING: TimescaleDB does not support removing dimensions. The following dimensions cannot be removed: {dimensionList}");
+            }
+
             return statements;
         }
     }

CmdScale.EntityFrameworkCore.TimescaleDB/Internals/Features/Hypertables/HypertableDiffer.cs

@@ -1,4 +1,5 @@
-using CmdScale.EntityFrameworkCore.TimescaleDB.Operations;
+using CmdScale.EntityFrameworkCore.TimescaleDB.Abstractions;
+using CmdScale.EntityFrameworkCore.TimescaleDB.Operations;
 using Microsoft.EntityFrameworkCore.Metadata;
 using Microsoft.EntityFrameworkCore.Migrations.Operations;
 
@@ -28,7 +29,8 @@ public IReadOnlyList<MigrationOperation> GetDifferences(IRelationalModel? source
                 .Where(x =>
                     x.Target.ChunkTimeInterval != x.Source.ChunkTimeInterval ||
                     x.Target.EnableCompression != x.Source.EnableCompression ||
-                    !AreChunkSkipColumnsEqual(x.Target.ChunkSkipColumns, x.Source.ChunkSkipColumns)
+                    !AreChunkSkipColumnsEqual(x.Target.ChunkSkipColumns, x.Source.ChunkSkipColumns) ||
+                    !AreDimensionsEqual(x.Target.AdditionalDimensions, x.Source.AdditionalDimensions)
                 );
 
             foreach (var hypertable in updatedHypertables)
@@ -40,9 +42,11 @@ public IReadOnlyList<MigrationOperation> GetDifferences(IRelationalModel? source
                     ChunkTimeInterval = hypertable.Target.ChunkTimeInterval,
                     EnableCompression = hypertable.Target.EnableCompression,
                     ChunkSkipColumns = hypertable.Target.ChunkSkipColumns,
+                    AdditionalDimensions = hypertable.Target.AdditionalDimensions,
                     OldChunkTimeInterval = hypertable.Source.ChunkTimeInterval,
                     OldEnableCompression = hypertable.Source.EnableCompression,
-                    OldChunkSkipColumns = hypertable.Source.ChunkSkipColumns
+                    OldChunkSkipColumns = hypertable.Source.ChunkSkipColumns,
+                    OldAdditionalDimensions = hypertable.Source.AdditionalDimensions
                 });
             }
 
@@ -59,5 +63,29 @@ private static bool AreChunkSkipColumnsEqual(IReadOnlyList<string>? list1, IRead
 
             return new HashSet<string>(list1).SetEquals(list2);
         }
+
+        private static bool AreDimensionsEqual(IReadOnlyList<Dimension>? list1, IReadOnlyList<Dimension>? list2)
+        {
+            if (list1 == null && list2 == null) return true;
+            if (list1 == null || list2 == null) return false;
+            if (list1.Count != list2.Count) return false;
+
+            // Compare each dimension's properties
+            for (int i = 0; i < list1.Count; i++)
+            {
+                Dimension dim1 = list1[i];
+                Dimension dim2 = list2[i];
+
+                if (dim1.ColumnName != dim2.ColumnName ||
+                    dim1.Type != dim2.Type ||
+                    dim1.Interval != dim2.Interval ||
+                    dim1.NumberOfPartitions != dim2.NumberOfPartitions)
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
     }
 }

CmdScale.EntityFrameworkCore.TimescaleDB/Operations/AlterContinuousAggregateOperation.cs

@@ -9,10 +9,10 @@ public class AlterContinuousAggregateOperation : MigrationOperation
 
         public string? ChunkInterval { get; set; }
         public string? OldChunkInterval { get; set; }
-        
+
         public bool CreateGroupIndexes { get; set; }
         public bool OldCreateGroupIndexes { get; set; }
-        
+
         public bool MaterializedOnly { get; set; }
         public bool OldMaterializedOnly { get; set; }
     }

CmdScale.EntityFrameworkCore.TimescaleDB/Operations/AlterHypertableOperation.cs

@@ -1,4 +1,5 @@
-using Microsoft.EntityFrameworkCore.Migrations.Operations;
+using CmdScale.EntityFrameworkCore.TimescaleDB.Abstractions;
+using Microsoft.EntityFrameworkCore.Migrations.Operations;
 
 namespace CmdScale.EntityFrameworkCore.TimescaleDB.Operations
 {
@@ -13,9 +14,11 @@ public class AlterHypertableOperation : MigrationOperation
         // Only timestamp-like and Integer-like columns are supported for chunk skipping
         // Cannot be reverted once enabled
         public IReadOnlyList<string>? ChunkSkipColumns { get; set; }
+        public IReadOnlyList<Dimension>? AdditionalDimensions { get; set; }
 
         public string OldChunkTimeInterval { get; set; } = string.Empty;
         public bool OldEnableCompression { get; set; }
         public IReadOnlyList<string>? OldChunkSkipColumns { get; set; }
+        public IReadOnlyList<Dimension>? OldAdditionalDimensions { get; set; }
     }
 }