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Caution
You're viewing documentation for an unstable version of Scylla Rust Driver. Switch to the latest stable version.
ExecutionProfileHandle
s 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.
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
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