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Remapping execution profile handles

ExecutionProfileHandles can be remapped to another ExecutionProfile, and the change affects all sessions and statements that have been assigned that handle. This enables quick workload switches.

Example mapping:

  • session1 -> handle1 -> profile1
  • statement1 -> handle1 -> profile1
  • statement2 -> handle2 -> profile2

We can now remap handle2 to profile1, so that the mapping for statement2 becomes as follows:

  • statement2 -> handle2 -> profile1

We can also change statement1's handle to handle2, and remap handle1 to profile2, yielding:

  • session1 -> handle1 -> profile2
  • statement1 -> handle2 -> profile1
  • statement2 -> handle2 -> profile1

As you can see, profiles are a powerful and convenient way to define and modify your workloads.

Example

Below, the remaps described above are followed in code.

# extern crate scylla;
# use std::error::Error;
# async fn check_only_compiles() -> Result<(), Box<dyn Error>> {
use scylla::{Session, SessionBuilder};
use scylla::query::Query;
use scylla::statement::Consistency;
use scylla::execution::ExecutionProfile;

let profile1 = ExecutionProfile::builder()
    .consistency(Consistency::One)
    .build();

let profile2 = ExecutionProfile::builder()
    .consistency(Consistency::Two)
    .build();

let mut handle1 = profile1.clone().into_handle();
let mut handle2 = profile2.clone().into_handle();

let session: Session = SessionBuilder::new()
    .known_node("127.0.0.1:9042")
    .default_execution_profile_handle(handle1.clone())
    .build()
    .await?;

let mut query1 = Query::from("SELECT * FROM ks.table");
let mut query2 = Query::from("SELECT pk FROM ks.table WHERE pk = ?");

query1.set_execution_profile_handle(Some(handle1.clone()));
query2.set_execution_profile_handle(Some(handle2.clone()));

// session1 -> handle1 -> profile1
// query1 -> handle1 -> profile1
// query2 -> handle2 -> profile2

// We can now remap handle2 to profile1:
handle2.map_to_another_profile(profile1);
// ...so that the mapping for query2 becomes as follows:
// query2 -> handle2 -> profile1

// We can also change query1's handle to handle2:
query1.set_execution_profile_handle(Some(handle2.clone()));
// ...and remap handle1 to profile2:
handle1.map_to_another_profile(profile2);
// ...yielding:
// session1 -> handle1 -> profile2
// query1 -> handle2 -> profile1
// query2 -> handle2 -> profile1

# Ok(())
# }