CODEWITHSUNDEEP
cassandradatastaxcassandra-3.0
BdEngineer
BdEngineer

Reputation: 3179

Can I user counter type field as primary key of my C* table?

When I am trying to create table like below

 create table if not exists counter_temp(id counter PRIMARY KEY , comment text);

It is giving error as below

Multiple markers at this line

  • For a table with counter columns, all columns except the primary key must be type counter

  • counter type is not supported for PRIMARY KEY part

Question 1 :

What is the reason , counter column not allowed as part of primary key?

Question 2 : While I am trying to create as below

create table if not exists counter_temp(id uuid PRIMARY KEY, counter_t counter, comment text)

Error : Cant mix counter and non-counter columns in the same table

What is wrong here ? how to handle it correct way ?

Question 3 :

I have a table emp( emp_id counter, emp_name text) in Dev env where has data , now I need to copy that data into another SIT env emp( emp_id counter, emp_name text) table ?

Can it be done will it copy counter fields properly ?

Upvotes: 0

Views: 293

Answers (1)

Alex Ott
Alex Ott

Reputation: 87119

Short answer for question 1 is No, as it was communicated in the error message. But Even if it was allowed, then it didn't make any sense - when you change value of the primary key, you're basically create a new row with different primary key.

for Q2 - if there is at least one counter column in the table, then all other regular columns should have type counter. If you need to add a comment field, just create a 2nd table, with UUID primary key & insert or read data to/from 2 tables at the same time.

for Q3 - cqlsh's COPY command supports tables with counters for newer Cassandra versions (where fix for CASSANDRA-9043 is implemented). Also, Spark Cassandra Connector is able to read from tables with counters & write to them. But in both cases make sure that the target table is empty, otherwise new values will be appended to existing ones.

Upvotes: 2

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