Better comments and logging in chunk migration

Author: emilk

crates/store/re_sorbet/src/migrations/mod.rs

@@ -1,6 +1,10 @@
 #![expect(non_snake_case)]
 
 //! These are the migrations that are introduced for each Sorbet version.
+//!
+//! When you introduce a breaking change, these are the steps:
+//! * Bump [`SorbetSchema::METADATA_VERSION`]
+//! * Add a new `mod vX_Y_Z__to__vX_Y_W`
 
 use std::cmp::Ordering;
 
@@ -109,7 +113,7 @@ pub fn migrate_record_batch(mut batch: RecordBatch) -> RecordBatch {
         Ok(batch_version) => match batch_version.cmp(&SorbetSchema::METADATA_VERSION) {
             Ordering::Equal => {
                 // Provide this code path as an early out to avoid unnecessary comparisons.
-                re_log::trace!("Batch version matches Sorbet version.");
+                re_log::trace!("Batch version matches Sorbet version ({batch_version})");
                 batch
             }
             Ordering::Less => {
@@ -120,7 +124,7 @@ pub fn migrate_record_batch(mut batch: RecordBatch) -> RecordBatch {
                     );
                     batch
                 } else {
-                    re_log::trace!("Performing migrations…");
+                    re_log::debug_once!("Performing migrations from {batch_version}…");
                     batch = maybe_apply::<v0_0_1__to__v0_0_2::Migration>(&batch_version, batch);
                     batch = maybe_apply::<v0_0_2__to__v0_1_0::Migration>(&batch_version, batch);
                     batch = maybe_apply::<v0_1_0__to__v0_1_1::Migration>(&batch_version, batch);