diff --git a/.github/actions/run-tests/reset-from-container.sh b/.github/actions/run-tests/reset-from-container.sh
index 059996341..fca3903ef 100755
--- a/.github/actions/run-tests/reset-from-container.sh
+++ b/.github/actions/run-tests/reset-from-container.sh
@@ -1,4 +1,4 @@
-#! /bin/sh -e
+#! /bin/bash -e
 
 BACKUP="$1"
 
@@ -13,8 +13,30 @@ case "$INPUT_DB" in
 		mysql -u root -p"$MYSQL_ROOT_PASSWORD" -h mysql < "/dumps/$BACKUP/sql/dump.sql"
 		;;
 	pgsql)
+		echo 'Dropping old data'
 		PGPASSWORD="$POSTGRES_PASSWORD" \
-		psql -d "$POSTGRES_DB" -h postgres -U "$POSTGRES_USER" < "/dumps/$BACKUP/sql/dump.sql"
+		psql -d "$POSTGRES_DB" -h postgres -U "$POSTGRES_USER" -v 'ON_ERROR_STOP=1' <<- EOF || exit 1
+			DROP SCHEMA public CASCADE;
+			CREATE SCHEMA public;
+			GRANT ALL ON SCHEMA public TO $POSTGRES_USER;
+			GRANT ALL ON SCHEMA public TO public;
+			EOF
+		
+# 		PGPASSWORD="$POSTGRES_PASSWORD" \
+# 		psql -d "$POSTGRES_DB" -h postgres -U "$POSTGRES_USER" <<- EOF
+# 			\l
+# 			\d
+# 			SELECT * FROM oc_preferences WHERE appid='cookbook';
+# 			EOF
+		
+		echo 'Inserting dump data'
+		PGPASSWORD="$POSTGRES_PASSWORD" \
+		psql -d "$POSTGRES_DB" -h postgres -U "$POSTGRES_USER" -f "/dumps/$BACKUP/sql/dump.sql" -v 'ON_ERROR_STOP=1' || exit 1
+		
+# 		PGPASSWORD="$POSTGRES_PASSWORD" \
+# 		psql -d "$POSTGRES_DB" -h postgres -U "$POSTGRES_USER" <<- EOF
+# 			SELECT * FROM oc_preferences WHERE appid='cookbook';
+# 			EOF
 		;;
 	sqlite)
 		echo "Doing nothing as it was already restored during data restoration."
diff --git a/.github/actions/run-tests/run-locally.sh b/.github/actions/run-tests/run-locally.sh
index c28a083eb..3e046dbe1 100755
--- a/.github/actions/run-tests/run-locally.sh
+++ b/.github/actions/run-tests/run-locally.sh
@@ -274,10 +274,12 @@ drop_environment(){
 			fi
 			;;
 		pgsql)
-			local tables=$(echo "SELECT tablename FROM pg_tables WHERE schemaname = 'public';" | call_postgres | head -n -1 )
-			if [ -n "$tables" ]; then
-				echo "$tables" | sed 's@.*@DROP TABLE \0;@' | call_postgres
-			fi
+			call_postgres <<- EOF
+				DROP SCHEMA public CASCADE;
+				CREATE SCHEMA public;
+				GRANT ALL ON SCHEMA public TO $POSTGRES_USER;
+				GRANT ALL ON SCHEMA public TO public;
+				EOF
 			;;
 	esac
 	
@@ -337,6 +339,12 @@ restore_env_dump() {
 			;;
 		pgsql)
 			echo "Restoring Postgres database from dump"
+			call_postgres <<- EOF
+				DROP SCHEMA public CASCADE;
+				CREATE SCHEMA public;
+				GRANT ALL ON SCHEMA public TO $POSTGRES_USER;
+				GRANT ALL ON SCHEMA public TO public;
+				EOF
 			cat "volumes/dumps/$ENV_DUMP_PATH/sql/dump.sql" | call_postgres
 			;;
 		sqlite)
@@ -424,7 +432,7 @@ function call_mysql() {
 
 function call_postgres() {
 	#docker-compose exec -T postgres psql -t nc_test tester
-	docker-compose exec -T postgres psql -U "$POSTGRES_USER" "$POSTGRES_DB"
+	docker-compose exec -T postgres psql -U "$POSTGRES_USER" "$POSTGRES_DB" -v 'ON_ERROR_STOP=1' --quiet "$@"
 }
 
 ##### Parameters as extracted from the CLI
diff --git a/.github/actions/run-tests/run-occ.sh b/.github/actions/run-tests/run-occ.sh
new file mode 100755
index 000000000..c6b53da16
--- /dev/null
+++ b/.github/actions/run-tests/run-occ.sh
@@ -0,0 +1,9 @@
+#! /bin/sh -e
+
+#set -x
+
+cd /nextcloud
+php occ "$@"
+
+exit $?
+
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c48838770..5975b2829 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@
 ### Fixed
 - Fixed changes from #774 and minor extensions
   [#775](https://github.com/nextcloud/cookbook/pull/775) @christianlupus
+- Clean tables from old, redundant, and non-unique data to allow migrations (see #762 #763)
+  [#776](https://github.com/nextcloud/cookbook/pull/776) @christianlupus
 
 
 ## 0.9.1 - 2021-07-05
diff --git a/lib/Migration/Version000000Date20210701093123.php b/lib/Migration/Version000000Date20210701093123.php
index c432b91d1..382aee400 100644
--- a/lib/Migration/Version000000Date20210701093123.php
+++ b/lib/Migration/Version000000Date20210701093123.php
@@ -4,16 +4,84 @@
 
 namespace OCA\Cookbook\Migration;
 
-use Closure;
+use OCP\IDBConnection;
 use OCP\DB\ISchemaWrapper;
 use OCP\Migration\IOutput;
 use OCP\Migration\SimpleMigrationStep;
+use Closure;
+use OCP\DB\QueryBuilder\IQueryBuilder;
 
 /**
  * Auto-generated migration step: Please modify to your needs!
  */
 class Version000000Date20210701093123 extends SimpleMigrationStep {
 
+	/**
+	 * @var IDBConnection
+	 */
+	private $db;
+	
+	public function __construct(IDBConnection $db) {
+		$this->db = $db;
+	}
+	
+	public function preSchemaChange(IOutput $output, \Closure $schemaClosure, array $options) {
+		$this->db->beginTransaction();
+		try {
+			$qb = $this->db->getQueryBuilder();
+			
+			// Fetch all rows that are non-unique
+			$qb->selectAlias('n.user_id', 'user')
+				->selectAlias('n.recipe_id', 'recipe')
+				->from('cookbook_names', 'n')
+				->groupBy('n.user_id', 'n.recipe_id')
+				->having('COUNT(*) > 1');
+			//echo $qb->getSQL() . "\n";
+			
+			$cursor = $qb->execute();
+			$result = $cursor->fetchAll();
+			
+			if (sizeof($result) > 0) {
+				// We have to fix the database
+				
+				// Drop all redundant rows
+				$qb = $this->db->getQueryBuilder();
+				$qb->delete('cookbook_names')
+					->where(
+						'user_id = :user',
+						'recipe_id = :recipe'
+						);
+				
+				$qb2 = $this->db->getQueryBuilder();
+				$qb2->update('preferences')
+					->set('configvalue', $qb->expr()->literal('1', IQueryBuilder::PARAM_STR))
+					->where(
+						'userid = :user',
+						'appid = :app',
+						'configkey = :property'
+						);
+				$qb2->setParameter('app', 'cookbook');
+				$qb2->setParameter('property', 'last_index_update');
+				
+				foreach ($result as $r) {
+					$qb->setParameter('user', $r['user']);
+					$qb->setParameter('recipe', $r['recipe']);
+					$qb->execute();
+					
+					$qb2->setParameter('user', $r['user']);
+					$qb2->execute();
+				}
+			}
+			
+			// Finish the transaction
+			$this->db->commit();
+		} catch (\Exception $e) {
+			// Abort the transaction
+			$this->db->rollBack();
+			throw $e;
+		}
+	}
+	
 	/**
 	 * @param IOutput $output
 	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
diff --git a/phpunit.integration.xml b/phpunit.integration.xml
index 0841ab065..cd7878cfe 100755
--- a/phpunit.integration.xml
+++ b/phpunit.integration.xml
@@ -1,4 +1,11 @@
-<phpunit bootstrap="tests/bootstrap.php" colors="true">
+<phpunit 
+	bootstrap="tests/bootstrap.php"
+	colors="true"
+	backupGlobals="false"
+	backupStaticAttributes="false"
+	cacheResult="true"
+	cacheResultFile="/tmp/phpunit.cache"
+	>
     <testsuites>
         <testsuite name="integration">
             <directory>./tests/Integration</directory>
@@ -6,12 +13,7 @@
     </testsuites>
 	<filter>
 		<whitelist processUncoveredFilesFromWhitelist="true" addUncoveredFilesFromWhitelist="true">
-			<directory suffix=".php">lib/</directory>
-			<!--<directory suffix=".php">lib/Controller</directory>
-			<directory suffix=".php">lib/Db</directory>
-			<directory suffix=".php">lib/Exception</directory>
-			<directory suffix=".php">lib/Migration</directory>
-			<directory suffix=".php">lib/Service</directory>-->
+			<directory suffix=".php">lib</directory>
 		</whitelist>
 	</filter>
 </phpunit>
diff --git a/phpunit.xml b/phpunit.xml
index 37327e5de..ee08c702e 100755
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,4 +1,11 @@
-<phpunit bootstrap="tests/bootstrap.php" colors="true">
+<phpunit 
+	bootstrap="tests/bootstrap.php"
+	colors="true"
+	backupGlobals="false"
+	backupStaticAttributes="false"
+	cacheResult="true"
+	cacheResultFile="/tmp/phpunit.cache"
+	>
     <testsuites>
         <testsuite name="unit">
             <directory>./tests/Unit</directory>
@@ -7,11 +14,6 @@
 	<filter>
 		<whitelist processUncoveredFilesFromWhitelist="true" addUncoveredFilesFromWhitelist="true">
 			<directory suffix=".php">lib</directory>
-			<!--<directory suffix=".php">lib/Controller</directory>
-			<directory suffix=".php">lib/Db</directory>
-			<directory suffix=".php">lib/Exception</directory>
-			<directory suffix=".php">lib/Migration</directory>
-			<directory suffix=".php">lib/Service</directory>-->
 		</whitelist>
 	</filter>
 </phpunit>
diff --git a/tests/Integration/Setup/Migrations/Version000000Date20210701093123Test.php b/tests/Integration/Setup/Migrations/Version000000Date20210701093123Test.php
new file mode 100644
index 000000000..bccd92d34
--- /dev/null
+++ b/tests/Integration/Setup/Migrations/Version000000Date20210701093123Test.php
@@ -0,0 +1,205 @@
+<?php
+
+namespace tests\Integration\Setup\Migrations;
+
+use OCP\IDBConnection;
+use OCP\AppFramework\App;
+use OCP\AppFramework\IAppContainer;
+use OCP\DB\QueryBuilder\IQueryBuilder;
+use OC\DB\SchemaWrapper;
+use PHPUnit\Framework\TestCase;
+use OC\DB\MigrationService;
+use OC\DB\Connection;
+use OCP\Util;
+
+class Version000000Date20210701093123Test extends TestCase {
+	
+	/**
+	 * @var IAppContainer
+	 */
+	private $container;
+	
+	/**
+	 * @var IDBConnection
+	 */
+	private $db;
+	
+	/**
+	 * @var MigrationService
+	 */
+	private $migrationService;
+	
+	public function setUp(): void {
+		resetEnvironmentToBackup('default');
+		
+		parent::setUp();
+		
+		$app = new App('cookbook');
+		$this->container = $app->getContainer();
+		
+		/**
+		 * @var IDBConnection $db
+		 */
+		$this->db = $this->container->query(IDBConnection::class);
+		$this->assertIsObject($this->db);
+		/**
+		 * @var SchemaWrapper $schema
+		 */
+		$schema = $this->container->query(SchemaWrapper::class);
+		$this->assertIsObject($schema);
+		
+		if (Util::getVersion()[0] >= 21) {
+			$connection = \OC::$server->query(Connection::class);
+		} else {
+			$connection = $this->db;
+		}
+		$this->migrationService = new MigrationService('cookbook', $connection);
+		
+		// undo all migrations of cookbook app
+		$qb = $this->db->getQueryBuilder();
+		$numRows = $qb->delete('migrations')
+			->where('app=:app')
+			->setParameter('app', 'cookbook')
+			->execute();
+		$this->assertGreaterThan(0, $numRows);
+		
+		$schema->dropTable('cookbook_names');
+		$this->assertFalse($schema->hasTable('cookbook_names'));
+		$schema->dropTable('cookbook_categories');
+		$this->assertFalse($schema->hasTable('cookbook_categories'));
+		$schema->dropTable('cookbook_keywords');
+		$this->assertFalse($schema->hasTable('cookbook_keywords'));
+		
+		$schema->performDropTableCalls();
+		
+		// Reinstall app partially (just before the migration)
+		$this->migrationService->migrate('000000Date20210427082010');
+	}
+	
+	protected function tearDown(): void {
+		unset($this->container);
+		unset($this->db);
+		unset($this->migrationService);
+	}
+	
+	/**
+	 * @dataProvider dataProvider
+	 * @runInSeparateProcess
+	 * @covers \OCA\Cookbook\Migration\Version000000Date20210701093123
+	 */
+	public function testRedundantEntriesInDB($data, $updatedUsers) {
+		// Add recipe dummy data from data provider
+		$qb = $this->db->getQueryBuilder();
+		$qb->insert('cookbook_names')
+			->values([
+				'recipe_id' => ':recipe',
+				'user_id' => ':user',
+				'name' => ':name',
+			]);
+		$qb->setParameter('name', 'name of the recipe');
+		foreach ($data as $d) {
+			$qb->setParameter('user', $d[0]);
+			$qb->setParameter('recipe', $d[1]);
+			
+			$this->assertEquals(1, $qb->execute());
+		}
+		
+		// Initialize configuration values to track reindex timestamps
+		$current = time();
+		
+		$qb = $this->db->getQueryBuilder();
+		$qb->insert('preferences')
+			->values([
+				'userid' => ':user',
+				'appid' => ':appid',
+				'configkey' => ':property',
+				'configvalue' => ':value',
+			]);
+		
+		$qb->setParameter('value', $current, IQueryBuilder::PARAM_STR);
+		$qb->setParameter('appid', 'cookbook');
+		$qb->setParameter('property', 'last_index_update');
+		
+		$users = array_unique(array_map(function ($x) {
+			return $x[0];
+		}, $data));
+		foreach ($users as $u) {
+			$qb->setParameter('user', $u);
+			$this->assertEquals(1, $qb->execute());
+		}
+		
+		// Run the migration under test
+		$this->migrationService->migrate('000000Date20210701093123');
+		
+		// Get the (updated) reindex timestamps
+		$qb = $this->db->getQueryBuilder();
+		$qb->select('userid', 'configvalue')
+			->from('preferences')
+			->where(
+				'appid = :appid',
+				'configkey = :property'
+				);
+		$qb->setParameter('appid', 'cookbook');
+		$qb->setParameter('property', 'last_index_update');
+		
+		$cursor = $qb->execute();
+		$result = $cursor->fetchAll();
+		
+		// Filter those entries from the configuration that were marked as to be reindexed
+		$result = array_filter($result, function ($x) use ($current) {
+			return $x['configvalue'] < $current;
+		});
+		// Map the array to contain only the corresponding user names
+		$changedUsers = array_map(function ($x) {
+			return $x['userid'];
+		}, $result);
+		
+		// Sort the arrays to allow comparision of them
+		sort($changedUsers);
+		sort($updatedUsers);
+		
+		$this->assertEquals($updatedUsers, $changedUsers);
+	}
+	
+	public function dataProvider() {
+		return [
+			'caseA' => [
+				[
+					['alice', 123],
+					['alice', 124],
+					['bob', 125]
+				],
+				[],
+			],
+			'caseB' => [
+				[
+					['alice', 123],
+					['alice', 124],
+					['bob', 124],
+					['bob', 125],
+				],
+				[],
+			],
+			'caseC' => [
+				[
+					['alice', 123],
+					['alice', 124],
+					['bob', 124],
+					['bob', 124],
+					['bob', 125],
+				],
+				['bob']
+			],
+			'caseD' => [
+				[
+					['alice', 124],
+					['alice', 124],
+					['bob', 124],
+					['bob', 124],
+					['bob', 125],
+				],
+				['alice', 'bob']
+			],
+		];
+	}
+}
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 3d022ac93..d7ea801f6 100755
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -5,12 +5,33 @@
 // Fix for "Autoload path not allowed: .../cookbook/tests/testcase.php"
 \OC_App::loadApp('cookbook');
 
-function resetEnvironmentToBackup(string $name = 'default') {
+function resetEnvironmentToBackup(string $name = 'default', bool $forceprint = false) {
+	$output = [];
+	$ret = -1;
 	exec("./.github/actions/run-tests/reset-from-container.sh $name 2>&1", $output, $ret);
-	if ($ret !== 0) {
+	if ($ret !== 0 || $forceprint) {
 		echo "\nStandard output:\n";
 		print_r($output);
 		echo "Return value: $ret\n";
-		throw new Exception("Could not reset environment");
+		if ($ret !== 0) {
+			throw new Exception("Could not reset environment");
+		}
+	}
+}
+
+function runOCCCommand(array $args, bool $forceprint = false) {
+	$output = [];
+	$ret = -1;
+	$params = join(' ', array_map(function ($x) {
+		return escapeshellarg($x);
+	}, $args));
+	exec("./.github/actions/run-tests/run-occ.sh $params 2>&1", $output, $ret);
+	if ($ret !== 0 || $forceprint) {
+		echo "\nStandard output:\n";
+		print_r($output);
+		echo "Return value: $ret\n";
+		if ($ret !== 0) {
+			throw new Exception("Could not run OCC command");
+		}
 	}
 }