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  1. Core Server
  2. SERVER-56399

Configsvr step-up can fail after stepping-down during setFCV metadata patch-up

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    • Backwards Compatibility:
      Fully Compatible
    • Operating System:
      ALL

      Description

      Provided that featureFlagShardingFullDDLSupportTimestampedVersion is enabled, consider the following situation:
      1. Configsvr starts fcv upgrade 4.4 -> 5.0. Thus, persists kUpgradingFrom44To50 fcv value.
      2. Metadata patchup for phase-1 completes: This means that chunks now have uuid, we have build the uuid_1_* indexes and dropped the ns_1_* indexes for config.chunks.
      3. Metadata patchup for phase-2 is in progress. We have (partially or completely) $unset the ns from the chunks.
      4. Before transitioning to fcv kVersion50, the configsvr steps down
      5. The new configsvr primary steps up, ShardingCatalogManager::initializeConfigDatabaseIfNeeded is called, which will call ShardingCatalogManager::_initConfigIndexes. Because the current fcv value is kUpgradingFrom44To50, it will create the indexes for ns_1_*, but he have already $unset the 'ns' fields from the config.chunks, so it will fail due to DuplicateKey errors.

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            Assignee:
            jordi.serra-torrens Jordi Serra Torrens
            Reporter:
            jordi.serra-torrens Jordi Serra Torrens
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