Recovery of Cassandra from Truncate or Drop

1) Create keyspace

cassandra@cqlsh>CREATE KEYSPACE hireone WITH replication = {'class': 'NetworkTopologyStrategy', 'DC1': '2', 'DC2': '1'}

2) Create a table

cassandra@cqlsh:hireone> CREATE TABLE truncateanddrop (hero_of_usa text, hero_of_india text, id int primary key);

3) Describing the table that was created.

cassandra@cqlsh:hireone> DESC TABLE truncateanddrop ;

CREATE TABLE hireone.truncateanddrop (
    id int PRIMARY KEY,
    hero_of_india text,
    hero_of_usa text
) WITH bloom_filter_fp_chance = 0.01
    AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
    AND comment = ''
    AND compaction = {'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy', 'max_threshold': '32', 'min_threshold': '4'}
    AND compression = {'chunk_length_in_kb': '64', 'class': 'org.apache.cassandra.io.compress.LZ4Compressor'}
    AND crc_check_chance = 1.0
    AND dclocal_read_repair_chance = 0.1
    AND default_time_to_live = 0
    AND gc_grace_seconds = 864000
    AND max_index_interval = 2048
    AND memtable_flush_period_in_ms = 0
    AND min_index_interval = 128
    AND read_repair_chance = 0.0
    AND speculative_retry = '99PERCENTILE';

4) Inserting values into above table.

cassandra@cqlsh:hireone> INSERT INTO truncateanddrop (id, hero_of_india, hero_of_usa ) values (1,'president','prime_minister');

5) View the contents of the table.

cassandra@cqlsh:hireone> select * from truncateanddrop ;

 id | hero_of_india | hero_of_usa

----+---------------+----------------

  1 |     president | prime_minister

(1 rows)

6) Now truncate the table.

cassandra@cqlsh:hireone> TRUNCATE truncateanddrop ;

cassandra@cqlsh:hireone> select * from truncateanddrop ;

 id | hero_of_india | hero_of_usa

----+---------------+-------------

(0 rows)

7) By default the cassandra.yaml file will be enable to take snapshot automatically, so you will find the snapshot folder with in the data/your_table directory.

Property in yaml file: auto_snapshot: true

8) cd /var/lib/cassandra/hireone/truncateanddrop-xx/snapshots/table_directory

cp * /var/lib/cassandra/data/hireone/truncateanddrop-xx

***Above step need to be done on every node and on each datacenter.

9) Now we need to do a refresh of the keyspace table

nodetool refresh hireone truncateanddrop

*** Refresh also needs to be done on every node and on each datacenter

10) Now do a select from the table.

cassandra@cqlsh:hireone> select * from truncateanddrop  ;

 id | hero_of_india | hero_of_usa

----+---------------+----------------

  1 |     president | prime_minister

(1 rows)

11) If you drop the table also, its the same process.

***