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Date: Wed, 29 Mar 2017 17:25:41 +0000 (UTC)
From: "Zameer Manji (JIRA)" <jira@apache.org>
To: issues@aurora.apache.org
Message-ID: <JIRA.13060094.1490808305000.156554.1490808341647@Atlassian.JIRA>
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Subject: [jira] [Assigned] (AURORA-1912) DbSnapShot may remove enum values
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archived-at: Wed, 29 Mar 2017 17:25:46 -0000


     [ https://issues.apache.org/jira/browse/AURORA-1912?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zameer Manji reassigned AURORA-1912:
------------------------------------

    Assignee: Zameer Manji

> DbSnapShot may remove enum values
> ---------------------------------
>
>                 Key: AURORA-1912
>                 URL: https://issues.apache.org/jira/browse/AURORA-1912
>             Project: Aurora
>          Issue Type: Bug
>            Reporter: Zameer Manji
>            Assignee: Zameer Manji
>
> The dbnsapshot restore may truncate enum tables and cause referential integrity issues. From the code it restores from the SQL dump by first dropping all tables:
> {noformat}
>             try (Connection c = ((DataSource) store.getUnsafeStoreAccess()).getConnection()) {
>               LOG.info("Dropping all tables");
>               try (PreparedStatement drop = c.prepareStatement("DROP ALL OBJECTS")) {
>                 drop.executeUpdate();
>               }
> {noformat}
> However a freshly started leader will have some data in there from preparing the storage:
> {noformat}
>   @Override
>   @Transactional
>   protected void startUp() throws IOException {
>     Configuration configuration = sessionFactory.getConfiguration();
>     String createStatementName = "create_tables";
>     configuration.setMapUnderscoreToCamelCase(true);
>     // The ReuseExecutor will cache jdbc Statements with equivalent SQL, improving performance
>     // slightly when redundant queries are made.
>     configuration.setDefaultExecutorType(ExecutorType.REUSE);
>     addMappedStatement(
>         configuration,
>         createStatementName,
>         CharStreams.toString(new InputStreamReader(
>             DbStorage.class.getResourceAsStream("schema.sql"),
>             StandardCharsets.UTF_8)));
>     try (SqlSession session = sessionFactory.openSession()) {
>       session.update(createStatementName);
>     }
>     for (CronCollisionPolicy policy : CronCollisionPolicy.values()) {
>       enumValueMapper.addEnumValue("cron_policies", policy.getValue(), policy.name());
>     }
>     for (MaintenanceMode mode : MaintenanceMode.values()) {
>       enumValueMapper.addEnumValue("maintenance_modes", mode.getValue(), mode.name());
>     }
>     for (JobUpdateStatus status : JobUpdateStatus.values()) {
>       enumValueMapper.addEnumValue("job_update_statuses", status.getValue(), status.name());
>     }
>     for (JobUpdateAction action : JobUpdateAction.values()) {
>       enumValueMapper.addEnumValue("job_instance_update_actions", action.getValue(), action.name());
>     }
>     for (ScheduleStatus status : ScheduleStatus.values()) {
>       enumValueMapper.addEnumValue("task_states", status.getValue(), status.name());
>     }
>     for (ResourceType resourceType : ResourceType.values()) {
>       enumValueMapper.addEnumValue("resource_types", resourceType.getValue(), resourceType.name());
>     }
>     for (Mode mode : Mode.values()) {
>       enumValueMapper.addEnumValue("volume_modes", mode.getValue(), mode.name());
>     }
>     createPoolMetrics();
>   }
> {noformat}
> Consider the case where we add a new value to an existing enum. This means restoring from a snapshot will not allow us to have that value in the enum table. 
> To fix this we should have a migration for every enum value we add. However to me it seems that the better idea would be to update the enum tables after we restore from a snapshot.


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