Uploaded image for project: 'Core Server'
  1. Core Server
  2. SERVER-58082

Fail resharding operation if allowMigrations has already been set to false

    XMLWordPrintable

Details

    • Task
    • Status: Closed
    • Major - P3
    • Resolution: Fixed
    • None
    • 5.0.4, 5.1.0-rc0
    • Sharding
    • None
    • Fully Compatible
    • v5.0
    • Sharding 2021-07-12, Sharding 2021-07-26, Sharding 2021-08-09, Sharding 2021-08-23
    • 1

    Description

      The allowMigrations field was initially added to the config.collections entry as part of SERVER-50027 to prevent chunk migrations from successfully committing during a resharding operation. It is now also used by DDL operations for a similar reason. DDL operations such as dropping a database, dropping a collection, or renaming a collection are mutually exclusive with resharding due to the distributed lock being held. However, it would be safer if the resharding operation failed if allowMigrations has already been set to false. The idea is that a resharding operation should only proceed to shuffle data around in the sharded cluster if it was the one which set allowMigrations to false. Similarly, the resharding coordinator must not unset the allowMigrations field if the resharding operation aborts due to allowMigrations already being set to false.

      241
      switch (nextState) {
      242
          case CoordinatorStateEnum::kInitializing: {
      243
              // Append 'reshardingFields' to the config.collections entry for the original nss
      244
              TypeCollectionReshardingFields originalEntryReshardingFields(
      245
                  coordinatorDoc.getReshardingUUID());
      246
              originalEntryReshardingFields.setState(coordinatorDoc.getState());
      247
       
      248
              return BSON("$set" << BSON(CollectionType::kReshardingFieldsFieldName
      249
                                          << originalEntryReshardingFields.toBSON()
      250
                                          << CollectionType::kUpdatedAtFieldName
      251
                                          << opCtx->getServiceContext()->getPreciseClockSource()->now()
      252
                                          << CollectionType::kAllowMigrationsFieldName << false));
      253
          }
      

      Attachments

        Issue Links

          Activity

            People

              randolph@mongodb.com Randolph Tan
              max.hirschhorn@mongodb.com Max Hirschhorn
              Votes:
              0 Vote for this issue
              Watchers:
              2 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved: