Restore tables¶

Prerequisites¶

• Scylla Manager requires CQL credentials with:

  • permission to alter restored tables.

  • permission to drop and create Materialized Views and Secondary Indexes of restored tables.

• Restoring the content of the tables assumes that the correct schema (identical as in the backup) is already present in the destination cluster.

  Scylla Manager does NOT validate that, so it’s user responsibility to ensure it. The only form of validation that Scylla Manager performs is checking whether restored tables are present in destination cluster, but it does not validate their columns types nor other properties. In case destination cluster is missing correct schema, it should be restored first.

  Note that this requirement also applies to the keyspace schema. Keyspace (where restored tables live) should have the correct schema, including the replication strategy. It can be changed after successful restore according to: How to Safely Increase the Replication Factor.

• It is strongly advised to restore the contents of the tables only into truncated tables.

  Otherwise, restored tables’ contents might be overwritten by the already existing ones. Note that an empty table is not necessarily truncated!

• All nodes in restore destination cluster should be in the UN state (See nodetool status for details).

Process¶

Restore procedure works iteratively over restored locations, manifests and tables.

• For each backup location:

  • Find live Scylla nodes that will be used for restoring current location

    • Find nodes local to location

    • If non can be found, find any node with location access

  • List backup manifests for specified snapshot tag

• Record restored views definitions and drop them

• Record restored tables tombstone_gc mode and change it to tombstone_gc = {'mode': 'disabled'} (ensure restored data consistency)

• For each manifest:

  • Filter relevant tables from the manifest

  • For each table:

    • Group SSTables to bundles by ID

    • Join bundles into batches containing batch size bundles each

• For each batch (in --parallel):

  • Select node with enough free space to restore given batch

  • Download batch to node’s upload directory

  • Call load and stream with primary_replica_only

• Repair restored tables

• Reset all restored tables tombstone_gc to its original mode

• Recreate restored views

Information about original tombstone_gc mode, views definitions and repair progress is included in sctool progress –details.