feat: index column ordering in migrations (#665)

Support index column ordering in migrations.

Credits: @sdahps

Replaces #631
Fixex #630

Author: olavloite

Google.Cloud.EntityFrameworkCore.Spanner.Tests/MigrationTests/GenerateCreateScriptTest.cs

@@ -169,6 +169,8 @@ INTERLEAVE IN PARENT `Albums` ON DELETE NO ACTION
 
 CREATE INDEX `AlbumsByAlbumTitle2` ON `Albums` (`Title`) STORING (`MarketingBudget`, `ReleaseDate`)
 
+CREATE INDEX `AlbumsBySingerIdReleaseDateMarketingBudgetTitle` ON `Albums` (`SingerId`, `ReleaseDate` DESC, `MarketingBudget` DESC, `Title`)
+
 CREATE INDEX `idx_concerts_singerId_startTime` ON `Concerts` (`SingerId`, `StartTime`),
  INTERLEAVE IN `Singers`
 
@@ -282,6 +284,8 @@ INTERLEAVE IN PARENT `Albums` ON DELETE NO ACTION
 
 CREATE INDEX `AlbumsByAlbumTitle2` ON `Albums` (`Title`) STORING (`MarketingBudget`, `ReleaseDate`)
 
+CREATE INDEX `AlbumsBySingerIdReleaseDateMarketingBudgetTitle` ON `Albums` (`SingerId`, `ReleaseDate` DESC, `MarketingBudget` DESC, `Title`)
+
 CREATE INDEX `idx_concerts_singerId_startTime` ON `Concerts` (`SingerId`, `StartTime`),
  INTERLEAVE IN `Singers`
 
@@ -395,6 +399,8 @@ INTERLEAVE IN PARENT `Albums` ON DELETE NO ACTION
 
 CREATE INDEX `AlbumsByAlbumTitle2` ON `Albums` (`Title`) STORING (`MarketingBudget`, `ReleaseDate`)
 
+CREATE INDEX `AlbumsBySingerIdReleaseDateMarketingBudgetTitle` ON `Albums` (`SingerId`, `ReleaseDate` DESC, `MarketingBudget` DESC, `Title`)
+
 CREATE INDEX `idx_concerts_singerId_startTime` ON `Concerts` (`SingerId`, `StartTime`),
  INTERLEAVE IN `Singers`
 

Google.Cloud.EntityFrameworkCore.Spanner.Tests/MigrationTests/Models/SpannerMigrationSampleDbContext.cs

@@ -54,6 +54,9 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
                 entity.HasIndex(e => e.Title)
                     .HasDatabaseName("AlbumsByAlbumTitle2")
                     .Storing(a => new { a.MarketingBudget, a.ReleaseDate });
+                entity.HasIndex(e => new { e.SingerId, e.ReleaseDate, e.MarketingBudget, e.Title })
+                    .IsDescending(false, true, true, false)
+                    .HasDatabaseName("AlbumsBySingerIdReleaseDateMarketingBudgetTitle");
 
                 entity.HasOne(d => d.Singer)
                     .WithMany(p => p.Albums)

Google.Cloud.EntityFrameworkCore.Spanner/Migrations/SpannerMigrationsSqlGenerator.cs

@@ -133,9 +133,9 @@ protected override void Generate(
                 .Append(Dependencies.SqlGenerationHelper.DelimitIdentifier(operation.Name))
                 .Append(" ON ")
                 .Append(Dependencies.SqlGenerationHelper.DelimitIdentifier(operation.Table, operation.Schema))
-                .Append(" (")
-                .Append(ColumnList(operation.Columns))
-                .Append(")");
+                .Append(" (");
+            GenerateIndexColumnList(operation, model, builder);
+            builder.Append(")");
 
             if (operation[SpannerAnnotationNames.Storing] is string[] storingColumns
                             && storingColumns.Length > 0)