Operations on table in Cassandra
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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