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BatchesΒΆ
Note: Cassandra 2.0+ is required.
Batches can be used to group multiple mutations (UPDATE, INSERT, DELETE) together into a single statement; simple or prepared. There are three different types of batches supported by Cassandra 2.0 or later.
CASS_BATCH_TYPE_LOGGEDis used to make sure that multiple mutations across multiple partitions happen atomically, that is, all the included mutations will eventually succeed. However, there is a performance penalty imposed by atomicity guarantee.CASS_BATCH_TYPE_UNLOGGEDis generally used to group mutations for a single partition and do not suffer from the performance penalty imposed by logged batches, but there is no atomicity guarantee for multi-partition updates.CASS_BATCH_TYPE_COUNTERis used to group counters updates.
Important: Be careful when using batches as a performance optimization.
void execute_batch(CassSession* session) {
/* This logged batch will make sure that all the mutations eventually succeed */
CassBatch* batch = cass_batch_new(CASS_BATCH_TYPE_LOGGED);
/* Statements can be immediately freed after being added to the batch */
{
CassStatement* statement
= cass_statement_new("INSERT INTO example1(key, value) VALUES ('a', '1')", 0);
cass_batch_add_statement(batch, statement);
cass_statement_free(statement);
}
{
CassStatement* statement
= cass_statement_new("UPDATE example2 set value = '2' WHERE key = 'b'", 0);
cass_batch_add_statement(batch, statement);
cass_statement_free(statement);
}
{
CassStatement* statement
= cass_statement_new("DELETE FROM example3 WHERE key = 'c'", 0);
cass_batch_add_statement(batch, statement);
cass_statement_free(statement);
}
CassFuture* batch_future = cass_session_execute_batch(session, batch);
/* Batch objects can be freed immediately after being executed */
cass_batch_free(batch);
/* This will block until the query has finished */
CassError rc = cass_future_error_code(batch_future);
printf("Batch result: %s\n", cass_error_desc(rc));
cass_future_free(batch_future);
}