Tombstones: Configuration

• This page covers the configuration keys that control tombstone cleanup.

• To learn how to apply these keys, see the Configuration Overview.

• To learn about tombstones and how their cleanup works, see the Tombstones overview.

• In this article:

  • Tombstone cleanup settings
    • Tombstones.CleanupIntervalInMin
    • Pull replication hub keys
      • Tombstones.RetentionTimeWithReplicationHubInHrs
      • Tombstones.CleanupIntervalWithReplicationHubInMin

Tombstone cleanup settings

Tombstones.CleanupIntervalInMin

The time interval between tombstone cleanups. This applies to every database.

• Type: TimeUnit.Minutes
• Default: 5
• Scope: Server-wide or per database

Pull replication hub keys

Tombstones held by a pull replication hub are meant to be processed by sink tasks.
But the sink tasks may take their time before reconnecting to the hub; they may even never reconnect.
Therefore, waiting for all sinks to connect and consume the tombstones before cleaning them up could cause the hub to accumulate tombstones indefinitely.
Instead, the hub uses a retention period for tombstone cleanup, set by a dedicated configuration key (to 14 days by default).

• A sink that reconnects with the hub within the retention period will receive all deletion operations.
• A sink that stays offline longer than the retention period misses the deletions whose tombstones have already been removed.

Example: tombstone retention on a hub

• A pull replication hub task runs on the database of a head-office, with its cleanup retention time set to 10 days.
• Offices in other countries run sink tasks that connect to the hub only occasionally.
• Since tombstones are kept for 10 days, an office that connects every week or so will receive every deletion held by the hub.
• An office that connects after two weeks, though, may miss some of the deletions whose tombstones were already removed.

Other processes still apply

Even after the retention period passes, a tombstone is not cleaned up while any other process (indexing, ETL, backup, and so on) still needs it.

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Tombstones.RetentionTimeWithReplicationHubInHrs

On a pull replication hub, the time a tombstone is kept before it becomes eligible for removal.

• Type: TimeUnit.Hours
• Default: 336 (14 days)
• Scope: Server-wide or per database

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Tombstones.CleanupIntervalWithReplicationHubInMin

On a pull replication hub, the interval at which the hub checks for tombstones that have aged past the retention period.

• Type: TimeUnit.Minutes
• Default: 1440 (1 day)
• Scope: Server-wide or per database