CODEWITHSUNDEEP
cassandra
K.E.
K.E.

Reputation: 838

batch update cassandra with lightweight transaction

I am using cassandra 2.2.3 and want to make a batch update with two statements. Both using a lightweight transaction.

BEGIN BATCH
UPDATE account SET values['balance'] = 11 WHERE id = 1 IF values['balance'] = 10;
UPDATE account SET values['balance'] = 11 WHERE id = 2 IF values['balance'] = 10;
APPLY BATCH;

The batch returns following error: 

InvalidRequest: code=2200 [Invalid query] message="Batch with conditions cannot span multiple partitions".

I understand that it is not possible to make a batch on various PKs in the where clause because of the partitions, but why it is not possible to do a batch on the same PK? The problems are the IF statements, removing them, the batch is working.

So is there a solution to successfully execute such a batch update? Or any workaround?

EDIT: This is my schema:

CREATE TABLE booking.account (
 id int PRIMARY KEY,
 values map<varchar, decimal>,
 timestampCreate timestamp,
 timestampUpdate timestamp
);

Upvotes: 2

Views: 1778

Answers (1)

bydsky
bydsky

Reputation: 1794

I understand that it is not possible to make a batch on various PKs in the where clause because of the partitions, but why it is not possible to do a batch on the same PK?

You could make a batch on various PKs in the where clause, However this is not recommended (Please refer to Cassandra: Batch loading without the Batch keyword).

The problem here is conditional update (the if statement). Quote from datastax cql reference.

In Cassandra 2.0.6 and later, you can batch conditional updates introduced as lightweight transactions in Cassandra 2.0. Only updates made to the same partition can be included in the batch because the underlying Paxos implementation works at the granularity of the partition. You can group updates that have conditions with those that do not, but when a single statement in a batch uses a condition, the entire batch is committed using a single Paxos proposal, as if all of the conditions contained in the batch apply.

So do you really need batch statement? Read this Using and misusing batches

Upvotes: 2

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