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Execution profiles provide a mechanism to group together a set of configuration options and reuse them across different query executions. These options include:
Request timeout
Consistency and serial consistency level
Load balancing policy (*)
Retry Policy
* - Load balancing policies are disabled by default and must be explicity enabled for child policy settings to be applied (e.g. Token aware, latency aware, and filtering options)
Execution profiles are being introduced to help deal with the exploding number of configuration options, especially as the database platform evolves into more complex workloads. The number of options being introduced with the execution profiles is limited and may be expanded based on feedback from the community.
An execution profile must be associated with a cluster and will be made available for that session connection to attach to any statement before query execution.
/* Create a cluster object */
CassCluster* cluster = cass_cluster_new();
/* Create a new execution profile */
CassExecProfile* exec_profile = cass_execution_profile_new();
/* Set execution profile options */
cass_execution_profile_set_request_timeout(exec_profile,
120000); /* 2 min timeout */
cass_execution_profile_set_consistency(exec_profile,
CASS_CONSISTENCY_ALL);
/* Associate the execution profile with the cluster configuration */
cass_cluster_set_execution_profile(cluster,
"long_query",
exec_profile);
/* Execution profile may be freed once added to cluster configuration */
cass_execution_profile_free(exec_profile);
/* Provide the cluster object as configuration to connect the session */
The cluster configuration options will be used in place of any unassigned options after a connection is established. Once the execution profile is added to a cluster configuration it is immutable and any changes made will require the execution profile to be re-added before a session is connected in order for those settings to be available during query execution.
Note: There is no limit on how many execution profiles can be associated with a cluster/session; however the control connection may require more time to update the additional load balancing policies.
Execution profiles are copied from the cluster object to the session object during the session connection process.. To use an execution profile the name must be assigned to a statement.
void execute_with_a_profile(CassSession* session) {
CassStatement* statement = cass_statement_new("SELECT * FROM ...", 0);
/* OR create a prepared statement */
/* Assign the execution profile to the statement */
cass_statement_set_execution_profile(statement, "long_query");
/* Execute the statement */
CassFuture* query_future = cass_session_execute(session, statement);
/* ... */
cass_future_free(query_future);
cass_statement_free(statement);
}
Note: Use cass_batch_set_execution_profile(batch, "name") for batch
statements.
For statements that do not have an assigned execution profile, the default
cluster configuration options will be used. Those statements that have already
defined an execution profile and are being re-used can pass a NULL or empty
string "" when assigning the execution profile.
CassStatement* statement = cass_statement_new("SELECT * FROM ...", 0);
/* Remove the assigned execution profile */
cass_statement_set_execution_profile(statement, NULL);
/* ... */
cass_statement_free(statement);
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