diff --git a/database/migrations/2018_07_08_202724_create_table_comments_table.php b/database/-postponed/2018_07_08_202724_create_table_comments_table.php
similarity index 100%
rename from database/migrations/2018_07_08_202724_create_table_comments_table.php
rename to database/-postponed/2018_07_08_202724_create_table_comments_table.php
diff --git a/database/migrations/2018_07_08_203424_create_user_follows_table.php b/database/-postponed/2018_07_08_203424_create_user_follows_table.php
similarity index 100%
rename from database/migrations/2018_07_08_203424_create_user_follows_table.php
rename to database/-postponed/2018_07_08_203424_create_user_follows_table.php
diff --git a/database/migrations/2018_07_08_203801_create_discussion_follows_table.php b/database/-postponed/2018_07_08_203801_create_discussion_follows_table.php
similarity index 100%
rename from database/migrations/2018_07_08_203801_create_discussion_follows_table.php
rename to database/-postponed/2018_07_08_203801_create_discussion_follows_table.php
diff --git a/database/migrations/2018_07_08_204223_create_table_favourites_table.php b/database/-postponed/2018_07_08_204223_create_table_favourites_table.php
similarity index 100%
rename from database/migrations/2018_07_08_204223_create_table_favourites_table.php
rename to database/-postponed/2018_07_08_204223_create_table_favourites_table.php
diff --git a/database/migrations/2018_07_08_193638_create_data_tables_table.php b/database/migrations/2018_07_08_193638_create_data_tables_table.php
index 575e446..2309167 100644
--- a/database/migrations/2018_07_08_193638_create_data_tables_table.php
+++ b/database/migrations/2018_07_08_193638_create_data_tables_table.php
@@ -16,41 +16,51 @@ class CreateDataTablesTable extends Migration
         Schema::create('data_tables', function (Blueprint $table) {
             $table->increments('id');
             $table->timestamps();
-	        $table->unsignedInteger('owner_id');
-	        $table->unsignedInteger('parent_data_table_id')->nullable();
-	        $table->string('title');
-	        $table->string('license');
+            $table->unsignedInteger('owner_id');
+            $table->unsignedInteger('forked_from_id')->nullable();
+            $table->unsignedInteger('revision'); // incremented with each applied changeset
+            $table->string('title'); // indexable
+            $table->string('keywords'); // indexable
+            $table->text('description');
+            $table->string('license'); // license name (indexable)
+            $table->mediumText('license_text'); // space for custom license text, if needed
+            $table->longText('content');
 
-	        $table->foreign('owner_id')
-		        ->references('id')->on('users')
-		        ->onDelete('cascade');
+            $table->foreign('owner_id')
+                ->references('id')->on('users')
+                ->onDelete('cascade');
 
-	        $table->foreign('parent_data_table_id')
-		        ->references('id')->on('data_tables')
-		        ->onDelete('set null');
+            $table->foreign('forked_from_id')
+                ->references('id')->on('data_tables')
+                ->onDelete('set null');
+
+            $table->index('title'); // for text search
+            $table->index('keywords'); // for text search
+            $table->index('owner_id');
         });
 
-	    Schema::create('table_revisions', function (Blueprint $table) {
-		    $table->increments('id');
-		    $table->timestamps();
-		    $table->boolean('approved');
-		    $table->unsignedInteger('data_table_id');
-		    $table->unsignedInteger('parent_revision_id')->nullable();
-		    $table->unsignedInteger('author_id')->nullable();
-		    $table->longText('content');
+        Schema::create('changesets', function (Blueprint $table) {
+            $table->increments('id');
+            $table->timestamps();
+            $table->unsignedInteger('data_table_id');
+            $table->unsignedInteger('target_revision');
+            $table->boolean('applied');
+            $table->unsignedInteger('author_id')->nullable();
+            $table->longText('content'); // incremental changeset including original row values so that it can be reversed
 
-		    $table->foreign('data_table_id')
-			    ->references('id')->on('data_tables')
-			    ->onDelete('cascade');
+            $table->foreign('data_table_id')
+                ->references('id')->on('data_tables')
+                ->onDelete('cascade');
 
-		    $table->foreign('parent_revision_id')
-			    ->references('id')->on('table_revisions')
-			    ->onDelete('set null');
+            // Deleting a user should not delete their applied patches, as that would break history.
+            // We set the author to null and unmerged patches may be cleaned manually or by a separate query.
+            $table->foreign('author_id')
+                ->references('id')->on('users')
+                ->onDelete('set null');
 
-		    $table->foreign('author_id')
-			    ->references('id')->on('users')
-			    ->onDelete('set null');
-	    });
+            $table->index('author_id');
+            $table->index('data_table_id');
+        });
     }
 
     /**
@@ -60,7 +70,7 @@ class CreateDataTablesTable extends Migration
      */
     public function down()
     {
-	    Schema::dropIfExists('table_revisions');
+        Schema::dropIfExists('changesets');
         Schema::dropIfExists('data_tables');
     }
 }
diff --git a/database/migrations/2018_07_08_204449_create_oauth_identities_table.php b/database/migrations/2018_07_08_204449_create_oauth_identities_table.php
index d651117..8a6f7b2 100644
--- a/database/migrations/2018_07_08_204449_create_oauth_identities_table.php
+++ b/database/migrations/2018_07_08_204449_create_oauth_identities_table.php
@@ -24,6 +24,8 @@ class CreateOauthIdentitiesTable extends Migration
 	        $table->foreign('user_id')
 		        ->references('id')->on('users')
 		        ->onDelete('cascade');
+
+	        $table->index('user_id');
         });
     }