From 87ca67d4b63ed361290629b99d0302adfc21e88c Mon Sep 17 00:00:00 2001
From: Eric Eastwood <erice@element.io>
Date: Wed, 24 Jun 2026 15:03:51 -0500
Subject: [PATCH] Update comments

---
 rust/src/storage/db/mod.rs            | 9 +++++----
 rust/src/storage/db/python_db_pool.rs | 3 +++
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/rust/src/storage/db/mod.rs b/rust/src/storage/db/mod.rs
index c34ea2899e..88ed6dc21f 100644
--- a/rust/src/storage/db/mod.rs
+++ b/rust/src/storage/db/mod.rs
@@ -48,10 +48,9 @@ pub type ErasedResult = anyhow::Result<Box<dyn Any + Send>>;
 /// [`python_db_pool`]) or a native `tokio-postgres` pool (in `synapse-rust-apps`,
 /// see [`rust_db_pool`]).
 ///
-/// To keep the trait dyn-compatible, the only required method is the type-erased
-/// [`run_interaction_erased`](Self::run_interaction_erased); callers should
-/// prefer the ergonomic, generic
-/// [`run_interaction`](DatabasePoolExt::run_interaction).
+/// To keep the trait dyn-compatible, we have to specify a type-erased
+/// [`run_interaction_erased`](Self::run_interaction_erased) version; callers should
+/// prefer the ergonomic, generic [`run_interaction`](DatabasePoolExt::run_interaction).
 ///
 /// `Send + Sync` so it can be stored in a `#[pyclass]` and shared across threads.
 #[async_trait::async_trait]
@@ -140,6 +139,8 @@ pub trait DatabasePoolExt: DatabasePool {
     }
 }
 
+// Make [`run_interaction`](DatabasePoolExt::run_interaction) available on all
+// `DatabasePool`
 impl<T: DatabasePool + ?Sized> DatabasePoolExt for T {}
 
 /// A [`tokio_postgres::Transaction`] looking thing that we can use on the Rust side to
diff --git a/rust/src/storage/db/python_db_pool.rs b/rust/src/storage/db/python_db_pool.rs
index 53f9ac32a4..b2fbb7b511 100644
--- a/rust/src/storage/db/python_db_pool.rs
+++ b/rust/src/storage/db/python_db_pool.rs
@@ -231,6 +231,9 @@ pub struct LoggingTransactionWrapper {
     logging_transaction_py: Py<PyAny>,
 
     /// Disambiguate which underlying database engine we're working with
+    ///
+    /// Some features are only available on Postgres vs SQLite and the queries need to
+    /// be differentiated (for compatibility or performance reasons).
     pub database_engine: DatabaseEngine,
 }