diff --git a/Cargo.lock b/Cargo.lock
index 6e4c502f6c..55859345a8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,6 +1,6 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
 name = "adler2"
@@ -3180,7 +3180,7 @@ checksum = "28d3b2b1366ec20994f1fd18c3c594f05c5dd4bc44d8bb0c1c632c8d6829481f"
 [[package]]
 name = "salsa"
 version = "0.21.1"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=7edce6e248f35c8114b4b021cdb474a3fb2813b3#7edce6e248f35c8114b4b021cdb474a3fb2813b3"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=4818b15f3b7516555d39f5a41cb75970448bee4c#4818b15f3b7516555d39f5a41cb75970448bee4c"
 dependencies = [
  "boxcar",
  "compact_str",
@@ -3203,12 +3203,12 @@ dependencies = [
 [[package]]
 name = "salsa-macro-rules"
 version = "0.21.1"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=7edce6e248f35c8114b4b021cdb474a3fb2813b3#7edce6e248f35c8114b4b021cdb474a3fb2813b3"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=4818b15f3b7516555d39f5a41cb75970448bee4c#4818b15f3b7516555d39f5a41cb75970448bee4c"
 
 [[package]]
 name = "salsa-macros"
 version = "0.21.1"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=7edce6e248f35c8114b4b021cdb474a3fb2813b3#7edce6e248f35c8114b4b021cdb474a3fb2813b3"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=4818b15f3b7516555d39f5a41cb75970448bee4c#4818b15f3b7516555d39f5a41cb75970448bee4c"
 dependencies = [
  "heck",
  "proc-macro2",
diff --git a/Cargo.toml b/Cargo.toml
index 7461248654..f2a9343875 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -129,7 +129,7 @@ regex = { version = "1.10.2" }
 rustc-hash = { version = "2.0.0" }
 rustc-stable-hash = { version = "0.1.2" }
 # When updating salsa, make sure to also update the revision in `fuzz/Cargo.toml`
-salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "7edce6e248f35c8114b4b021cdb474a3fb2813b3" }
+salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "4818b15f3b7516555d39f5a41cb75970448bee4c" }
 schemars = { version = "0.8.16" }
 seahash = { version = "4.1.0" }
 serde = { version = "1.0.197", features = ["derive"] }
diff --git a/crates/ruff_db/src/files.rs b/crates/ruff_db/src/files.rs
index 32bbc619f1..cae4b51853 100644
--- a/crates/ruff_db/src/files.rs
+++ b/crates/ruff_db/src/files.rs
@@ -275,7 +275,12 @@ impl fmt::Debug for Files {
 impl std::panic::RefUnwindSafe for Files {}
 
 /// A file that's either stored on the host system's file system or in the vendored file system.
+///
+/// # Ordering
+/// Ordering is based on the file's salsa-assigned id and not on its values.
+/// The id may change between runs.
 #[salsa::input]
+#[derive(PartialOrd, Ord)]
 pub struct File {
     /// The path of the file (immutable).
     #[returns(ref)]
diff --git a/crates/ty_ide/src/lib.rs b/crates/ty_ide/src/lib.rs
index 27eb0fbbc6..9d862abac4 100644
--- a/crates/ty_ide/src/lib.rs
+++ b/crates/ty_ide/src/lib.rs
@@ -13,11 +13,10 @@ pub use hover::hover;
 pub use inlay_hints::inlay_hints;
 pub use markup::MarkupKind;
 
-use rustc_hash::FxHashSet;
-use std::ops::{Deref, DerefMut};
-
 use ruff_db::files::{File, FileRange};
 use ruff_text_size::{Ranged, TextRange};
+use rustc_hash::FxHashSet;
+use std::ops::{Deref, DerefMut};
 use ty_python_semantic::types::{Type, TypeDefinition};
 
 /// Information associated with a text range.
diff --git a/crates/ty_python_semantic/src/types.rs b/crates/ty_python_semantic/src/types.rs
index efe9eaa9d0..95246a5121 100644
--- a/crates/ty_python_semantic/src/types.rs
+++ b/crates/ty_python_semantic/src/types.rs
@@ -335,7 +335,12 @@ pub use crate::types::definition::TypeDefinition;
 pub(crate) use todo_type;
 
 /// Represents an instance of `builtins.property`.
+///
+/// # Ordering
+/// Ordering is based on the property instance's salsa-assigned id and not on its values.
+/// The id may change between runs, or when the property instance was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct PropertyInstanceType<'db> {
     getter: Option<Type<'db>>,
     setter: Option<Type<'db>>,
@@ -438,6 +443,7 @@ impl Default for DataclassTransformerParams {
 }
 
 /// Representation of a type: a set of possible values at runtime.
+///
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, salsa::Update)]
 pub enum Type<'db> {
     /// The dynamic type: a statically unknown set of values
@@ -5825,7 +5831,12 @@ pub enum TypeVarKind {
 /// typevar represents as an annotation: that is, an unknown set of objects, constrained by the
 /// upper-bound/constraints on this type var, defaulting to the default type of this type var when
 /// not otherwise bound to a type.
+///
+/// # Ordering
+/// Ordering is based on the type var instance's salsa-assigned id and not on its values.
+/// The id may change between runs, or when the type var instance was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct TypeVarInstance<'db> {
     /// The name of this TypeVar (e.g. `T`)
     #[returns(ref)]
@@ -6745,7 +6756,11 @@ impl<'db> OverloadedFunction<'db> {
     }
 }
 
+/// # Ordering
+/// Ordering is based on the function type's salsa-assigned id and not on its values.
+/// The id may change between runs, or when the function type was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct FunctionType<'db> {
     /// Name of the function at definition.
     #[returns(ref)]
@@ -7368,7 +7383,12 @@ impl KnownFunction {
 /// on an instance of a class. For example, the expression `Path("a.txt").touch` creates
 /// a bound method object that represents the `Path.touch` method which is bound to the
 /// instance `Path("a.txt")`.
+///
+/// # Ordering
+/// Ordering is based on the bounded method's salsa-assigned id and not on its values.
+/// The id may change between runs, or when the bounded method was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct BoundMethodType<'db> {
     /// The function that is being bound. Corresponds to the `__func__` attribute on a
     /// bound method object
@@ -7434,7 +7454,12 @@ impl<'db> BoundMethodType<'db> {
 /// It can be written in type expressions using `typing.Callable`. `lambda` expressions are
 /// inferred directly as `CallableType`s; all function-literal types are subtypes of a
 /// `CallableType`.
+///
+/// # Ordering
+/// Ordering is based on the callable type's salsa-assigned id and not on its values.
+/// The id may change between runs, or when the callable type was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct CallableType<'db> {
     #[returns(deref)]
     signatures: Box<[Signature<'db>]>,
@@ -7801,7 +7826,11 @@ pub enum WrapperDescriptorKind {
     PropertyDunderSet,
 }
 
+/// # Ordering
+/// Ordering is based on the module literal's salsa-assigned id and not on its values.
+/// The id may change between runs, or when the module literal was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct ModuleLiteralType<'db> {
     /// The file in which this module was imported.
     ///
@@ -7850,7 +7879,11 @@ impl<'db> ModuleLiteralType<'db> {
     }
 }
 
+/// # Ordering
+/// Ordering is based on the type alias's salsa-assigned id and not on its values.
+/// The id may change between runs, or when the alias was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct PEP695TypeAliasType<'db> {
     #[returns(ref)]
     pub name: ast::name::Name,
@@ -7876,7 +7909,11 @@ impl<'db> PEP695TypeAliasType<'db> {
     }
 }
 
+/// # Ordering
+/// Ordering is based on the type alias's salsa-assigned id and not on its values.
+/// The id may change between runs, or when the alias was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct BareTypeAliasType<'db> {
     #[returns(ref)]
     pub name: ast::name::Name,
@@ -8380,7 +8417,11 @@ impl<'db> IntersectionType<'db> {
     }
 }
 
+/// # Ordering
+/// Ordering is based on the string literal's salsa-assigned id and not on its value.
+/// The id may change between runs, or when the string literal was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct StringLiteralType<'db> {
     #[returns(deref)]
     value: Box<str>,
@@ -8401,7 +8442,11 @@ impl<'db> StringLiteralType<'db> {
     }
 }
 
+/// # Ordering
+/// Ordering is based on the byte literal's salsa-assigned id and not on its value.
+/// The id may change between runs, or when the byte literal was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct BytesLiteralType<'db> {
     #[returns(deref)]
     value: Box<[u8]>,
@@ -8413,7 +8458,11 @@ impl<'db> BytesLiteralType<'db> {
     }
 }
 
+/// # Ordering
+/// Ordering is based on the tuple's salsa-assigned id and not on its elements.
+/// The id may change between runs, or when the tuple was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct TupleType<'db> {
     #[returns(deref)]
     elements: Box<[Type<'db>]>,
diff --git a/crates/ty_python_semantic/src/types/class.rs b/crates/ty_python_semantic/src/types/class.rs
index 544c0e4437..586823f039 100644
--- a/crates/ty_python_semantic/src/types/class.rs
+++ b/crates/ty_python_semantic/src/types/class.rs
@@ -157,7 +157,12 @@ impl CodeGeneratorKind {
 }
 
 /// A specialization of a generic class with a particular assignment of types to typevars.
+///
+/// # Ordering
+/// Ordering is based on the generic aliases's salsa-assigned id and not on its values.
+/// The id may change between runs, or when the alias was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct GenericAlias<'db> {
     pub(crate) origin: ClassLiteral<'db>,
     pub(crate) specialization: Specialization<'db>,
@@ -503,7 +508,12 @@ impl<'db> From<ClassType<'db>> for Type<'db> {
 ///
 /// This does not in itself represent a type, but can be transformed into a [`ClassType`] that
 /// does. (For generic classes, this requires specializing its generic context.)
+///
+/// # Ordering
+/// Ordering is based on the class's id assigned by salsa and not on the class literal's values.
+/// The id may change between runs, or when the class literal was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct ClassLiteral<'db> {
     /// Name of the class at definition
     #[returns(ref)]
diff --git a/crates/ty_python_semantic/src/types/generics.rs b/crates/ty_python_semantic/src/types/generics.rs
index aa7e8c3c3d..eae850bbce 100644
--- a/crates/ty_python_semantic/src/types/generics.rs
+++ b/crates/ty_python_semantic/src/types/generics.rs
@@ -18,7 +18,12 @@ use crate::{Db, FxOrderSet};
 ///
 /// TODO: Handle nested generic contexts better, with actual parent links to the lexically
 /// containing context.
+///
+/// # Ordering
+/// Ordering is based on the context's salsa-assigned id and not on its values.
+/// The id may change between runs, or when the context was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub struct GenericContext<'db> {
     #[returns(ref)]
     pub(crate) variables: FxOrderSet<TypeVarInstance<'db>>,
diff --git a/crates/ty_python_semantic/src/types/instance.rs b/crates/ty_python_semantic/src/types/instance.rs
index d1ad4d47f9..e63a420cd1 100644
--- a/crates/ty_python_semantic/src/types/instance.rs
+++ b/crates/ty_python_semantic/src/types/instance.rs
@@ -160,7 +160,7 @@ impl<'db> From<NominalInstanceType<'db>> for Type<'db> {
 
 /// A `ProtocolInstanceType` represents the set of all possible runtime objects
 /// that conform to the interface described by a certain protocol.
-#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, PartialOrd, Ord, salsa::Update)]
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, salsa::Update, PartialOrd, Ord)]
 pub struct ProtocolInstanceType<'db> {
     pub(super) inner: Protocol<'db>,
 
diff --git a/crates/ty_python_semantic/src/types/protocol_class.rs b/crates/ty_python_semantic/src/types/protocol_class.rs
index 43d7697b61..005ea95765 100644
--- a/crates/ty_python_semantic/src/types/protocol_class.rs
+++ b/crates/ty_python_semantic/src/types/protocol_class.rs
@@ -58,7 +58,11 @@ impl<'db> Deref for ProtocolClassLiteral<'db> {
     }
 }
 
+/// # Ordering
+/// Ordering is based on the protocol interface member's salsa-assigned id and not on its members.
+/// The id may change between runs, or when the protocol instance members was garbage collected and recreated.
 #[salsa::interned(debug)]
+#[derive(PartialOrd, Ord)]
 pub(super) struct ProtocolInterfaceMembers<'db> {
     #[returns(ref)]
     inner: BTreeMap<Name, ProtocolMemberData<'db>>,
diff --git a/fuzz/Cargo.toml b/fuzz/Cargo.toml
index 8f3f9ac97c..6eca245196 100644
--- a/fuzz/Cargo.toml
+++ b/fuzz/Cargo.toml
@@ -30,7 +30,7 @@ ty_python_semantic = { path = "../crates/ty_python_semantic" }
 ty_vendored = { path = "../crates/ty_vendored" }
 
 libfuzzer-sys = { git = "https://github.com/rust-fuzz/libfuzzer", default-features = false }
-salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "7edce6e248f35c8114b4b021cdb474a3fb2813b3" }
+salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "4818b15f3b7516555d39f5a41cb75970448bee4c" }
 similar = { version = "2.5.0" }
 tracing = { version = "0.1.40" }