Operations on table in Cassandra - GeeksforGeeks

31 Dec, 2019
In this article, we will discuss table operations like Create insert truncate drop in Cassandra with some sample exercise. Let’s have a look.
Creating a table – Register:First, we are going to create a table namely as Register in which we have id, name, email, city are the fields. Let’s have a look.
Create table Register
 (
  id uuid primary key,
  name text,
  email text,
  city text
 );
Inserting data into Register table:After creating a table now, we are going to insert some data into Register table. Let’s have a look.
Insert into Register (id, name, email, city) 
values(uuid(), 'Ashish', 'ashish05.rana05@gmail.com', 'delhi');

Insert into Register (id, name, email, city) 
values(uuid(), 'abi', 'abc@gmail.com', 'mumbai');

Insert into Register (id, name, email, city) 
values(uuid(), 'rana', 'def@gmail.com', 'bangalore'); 
Verify the results:To verify the results using the following CQL query given below. Let’s have a look.
select * 
from Register; 
Describe the table schema:
describe table Register; 

CREATE TABLE cluster1.register (
    id uuid,
    city text,
    email text,
    name text,
    PRIMARY KEY (id)
) WITH read_repair_chance = 0.0
    AND dclocal_read_repair_chance = 0.0
    AND gc_grace_seconds = 864000
    AND 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 default_time_to_live = 0
    AND speculative_retry = '99PERCENTILE'
    AND min_index_interval = 128
    AND max_index_interval = 2048
    AND crc_check_chance = 1.0
    AND cdc = false
    AND memtable_flush_period_in_ms = 0; 
Updating the table:To update the table used the following CQL query given below.
update Register set 
email = 'abe@gmail.com' 
where id = 57280025-1261-44ab-85d4-62ab2c58a1c1; 
Verifying after updating the table:Let’s verify the results by using the following CQL query given below.
select * 
from Register; 
Output:
Alter operation on a table:To alter the table used the following CQL query given below.
ALTER table Register 
add events text; 
To see the update used the following CQL query given below.
describe table Register; 
Output:
CREATE TABLE cluster1.register (
    id uuid,
    city text,
    email text,
    events text,
    name text,
    PRIMARY KEY (id)
) WITH read_repair_chance = 0.0
    AND dclocal_read_repair_chance = 0.0
    AND gc_grace_seconds = 864000
    AND 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 default_time_to_live = 0
    AND speculative_retry = '99PERCENTILE'
    AND min_index_interval = 128
    AND max_index_interval = 2048
    AND crc_check_chance = 1.0
    AND cdc = false
    AND memtable_flush_period_in_ms = 0; 
Verifying the newly added column:To verify the newly added column used the following CQL query given below.
select * 
from Register; 
Output:
Inserting data into the new added column:
Insert into Register (id, name, email, city, events) 
values(uuid(), 'Ashish', 'ashish05.rana05@gmail.com', 'delhi', 'game'); 
To verify inserted data to the newly added column used the following CQL query given below.
select * 
from Register; 
Output:
Deleting data from table Register:To delete data from table Register used the following CQL query. Let’s have a look.
truncate Register; 
Delete a table:To delete table schema and data from table Register used the following CQL query. Let’s have a look.
drop table Register; 
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