PoC for 1-1 restore (VNODES)

[karol-kokoszka]

This PR is just to explore the 1-1 restore.

.1-1-restore-poc/backup.tar.gz is the archived snapshot.
To execute the PoC that restores simple backuptest_data.big_table table:

0. Clean the scylla data folders on containers.

make clean_restore

2. Extract information about the token ring from the backup manifest

make extract_tokens_and_schema

3. Set initial_token to the scylla.yaml per every node.

make set_initial_tokens

4. Start the cluster

make start-dev-env

5. Recreate schema

make recreate_schema

6. Extract SSTables from archive

make extract_sstables

7. Copy nodes SSTables to the /var/lib/scylla/data

make copy_sstables

8. Refresh the restored table.

make refresh_nodes

9. Query the amount of rows

make query_data

10. Extract restored data to sorted CSV (sorted by ID)

make extract_data_to_csv

11. Compare the restored content with expected one

make compare_restored

➜  scylla-manager git:(PoC-1-1-restore) ✗ make extract_data_to_csv 
Extracting data from Scylla table...
cqlsh 192.168.100.11 -u cassandra -p cassandra -e "COPY backuptest_data.big_table TO 'backuptest_data.big_table.restored.csv' WITH HEADER = TRUE;"
Using 11 child processes

Starting copy of backuptest_data.big_table with columns [id, data].
Processed: 2560 rows; Rate:    7451 rows/s; Avg. rate:    6158 rows/s
2560 rows exported to 1 files in 0.441 seconds.
Sorting the extracted data...
sort -t, -k1 backuptest_data.big_table.restored.csv > .1-1-restore-poc/backuptest_data.big_table.restored.sorted.csv
Removing unsorted CSV file...
rm backuptest_data.big_table.restored.csv
Data extraction and sorting complete!
➜  scylla-manager git:(PoC-1-1-restore) ✗ make compare_restored 
Comparing the content of restored ks with the expected content
Contents are the same

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• Code is split to commits that address a single change
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[karol-kokoszka]

Current scenario covers VNODEs only.
Another scenario with tablets must be created and tested (Is it enough to restore system tables related to tablets ?).

[karol-kokoszka]

UPDATE: This solution won't work for tablets and is not expected to work with tablets.
For tablet keyspaces, we will failback to load and stream.