Module scylla::transport::execution_profile

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ExecutionProfile is a grouping of configurable options regarding query execution.

Profiles can be created to represent different workloads, which thanks to them can be run conveniently on a single session.

There are two classes of objects related to execution profiles: ExecutionProfile and ExecutionProfileHandle. The former is simply an immutable set of the settings. The latter is a handle that at particular moment points to some ExecutionProfile (but during its lifetime, it can change the profile it points at). Handles are assigned to Sessions and Statements. At any moment, handles point to another ExecutionProfile. This allows convenient switching between workloads for all Sessions and/or Statements that, for instance, share common characteristics.

§Example

To create an ExecutionProfile and attach it as default for Session:

use scylla::{Session, SessionBuilder};
use scylla::statement::Consistency;
use scylla::transport::ExecutionProfile;

let profile = ExecutionProfile::builder()
    .consistency(Consistency::LocalOne)
    .request_timeout(None) // no request timeout
    .build();

let handle = profile.into_handle();

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

§Example

To create an ExecutionProfile and attach it to a Query:

use scylla::query::Query;
use scylla::statement::Consistency;
use scylla::transport::ExecutionProfile;
use std::time::Duration;

let profile = ExecutionProfile::builder()
    .consistency(Consistency::All)
    .request_timeout(Some(Duration::from_secs(30)))
    .build();

let handle = profile.into_handle();

let mut query1 = Query::from("SELECT * FROM ks.table");
query1.set_execution_profile_handle(Some(handle.clone()));

let mut query2 = Query::from("SELECT pk FROM ks.table WHERE pk = ?");
query2.set_execution_profile_handle(Some(handle));

§Example

To create an ExecutionProfile with config options defaulting to those set on another profile:

use scylla::statement::Consistency;
use scylla::transport::ExecutionProfile;
use std::time::Duration;

let base_profile = ExecutionProfile::builder()
    .request_timeout(Some(Duration::from_secs(30)))
    .build();

let profile = base_profile.to_builder()
    .consistency(Consistency::All)
    .build();

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.

use scylla::{Session, SessionBuilder};
use scylla::query::Query;
use scylla::statement::Consistency;
use scylla::transport::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

Structs§