From 458304859516cc066033ef6f189a4dc1d07d8219 Mon Sep 17 00:00:00 2001
From: Duncan Tourolle <duncan@tourolle.paris>
Date: Fri, 25 Sep 2026 22:05:02 -0400
Subject: [PATCH] Find a sidecar's photographs by an index range, not a
 case-insensitive LIKE

When a scan pull takes in sidecars another device wrote, `apply_judgement`
finds the photographs each one describes with
`source_ref LIKE '{stem}.%'`. SQLite's LIKE folds ASCII case, and nothing
indexes `source_ref` case-insensitively, so every lookup read all 24,000
names of the root through the `(root_id, source_ref)` index: 1.5-2 ms per
sidecar, 520-690 ms for the 342 `.drsc` files the reference catalog has
read. Another device culling a shoot is several hundred of them.

Every name beginning `{stem}.` lies in the half-open range
`[{stem}., {stem}/)` -- `/` is the byte after `.` -- which the unique key
serves as a seek. The rows LIKE matched beyond these differed only in
case, and the check that decides, `sidecar_path(source) == sidecar`, has
always compared exactly and refused them; the escaping of `%` and `_`
goes too, since a range has no wildcards.

persist_bench: 342 lookups 634-691 ms -> 9 ms CPU. Checked against the
reference catalog directly as well: for all 18,430 distinct sidecar
names its images imply, the range and the old LIKE, each filtered by
`sidecar_path`, pick the same photographs. A test pins the neighbours of
the range: a case variant, a longer stem, a subfolder named like the
stem, and a folder whose name holds `%` and `_`.

The XMP reader's LIKE (`xmp_sync::images_for`) is left alone: its check
is case-insensitive, so the range would not be a superset there, and it
only runs when the exact darktable-style name is not found.
---
 ui/dr-ui/src/library/scan.rs | 59 ++++++++++++++++++++++++++----------
 1 file changed, 43 insertions(+), 16 deletions(-)

diff --git a/ui/dr-ui/src/library/scan.rs b/ui/dr-ui/src/library/scan.rs
index 55b1855..dc17b8e 100644
--- a/ui/dr-ui/src/library/scan.rs
+++ b/ui/dr-ui/src/library/scan.rs
@@ -458,11 +458,11 @@ pub(super) fn record_sidecar_read(
 ///
 /// # Why the match is verified in Rust
 ///
-/// The `LIKE` narrows the search to rows sharing the stem, and it is only a
+/// The query narrows the search to rows sharing the stem, and it is only a
 /// filter: `library::sidecar_path` is what actually decides, applied to each
-/// candidate. A path holding a `%`, a `_` or a bracket would otherwise match
-/// more than it should, and a judgement landing on the wrong photograph is a
-/// silent, permanent wrong.
+/// candidate. A judgement landing on the wrong photograph is a silent,
+/// permanent wrong, so the rule lives in one place and the SQL only has to
+/// return a superset of what it accepts.
 ///
 /// Returns how many images gained a judgement they did not have.
 pub(super) fn apply_judgement(
@@ -479,24 +479,25 @@ pub(super) fn apply_judgement(
         .unwrap_or(sidecar)
         .to_string();
 
-    // The escape is the point: `%` and `_` are wildcards, and a photographer's
-    // folder is entitled to contain both.
-    let prefix = stem
-        .replace('\\', "\\\\")
-        .replace('%', "\\%")
-        .replace('_', "\\_");
-
+    // Every name that starts `{stem}.`, as a range over the
+    // `(root_id, source_ref)` key: `/` is the byte after `.`, so the half-open
+    // range holds exactly those names. It was a `LIKE`, and a `LIKE` is
+    // case-insensitive, which no index here can serve -- every sidecar a pull
+    // took in read all 24,000 names of the root, 1.5 ms each. The names it
+    // matched beyond these differed only in case, and the check below has
+    // always refused them: `sidecar_path` compares exactly.
     let candidates: Vec<(i64, String)> = {
         let mut stmt = conn
-            .prepare(
+            .prepare_cached(
                 "SELECT id, source_ref FROM images
-                  WHERE root_id = ?1 AND source_ref LIKE ?2 ESCAPE '\\'",
+                  WHERE root_id = ?1 AND source_ref >= ?2 AND source_ref < ?3",
             )
             .map_err(|e| e.to_string())?;
         let rows = stmt
-            .query_map(rusqlite::params![root_id, format!("{prefix}.%")], |r| {
-                Ok((r.get(0)?, r.get(1)?))
-            })
+            .query_map(
+                rusqlite::params![root_id, format!("{stem}."), format!("{stem}/")],
+                |r| Ok((r.get(0)?, r.get(1)?)),
+            )
             .map_err(|e| e.to_string())?;
         rows.filter_map(Result::ok)
             .filter(|(_, source): &(i64, String)| sidecar_path(source) == sidecar)
@@ -980,6 +981,32 @@ mod tests {
         );
     }
 
+    /// The lookup is a range over names starting `{stem}.`, so the names
+    /// either side of that range — a longer stem, a case variant, a folder
+    /// whose name holds the wildcards the old `LIKE` had to escape — must
+    /// neither be missed nor caught.
+    #[test]
+    fn a_sidecar_reaches_exactly_its_own_photographs() {
+        let cat = library(&[
+            "2026/50%_off/a.CR2",
+            "2026/50%_off/a.jpg",
+            "2026/50%_off/A.CR2",
+            "2026/50%_off/a.b.CR2",
+            "2026/50%_off/ab.CR2",
+            "2026/50%_off/a/b.CR2",
+            "2026/50Xxoff/a.CR2",
+        ]);
+        let n = apply_judgement(cat.connection(), 1, "2026/50%_off/a.drsc", 2, 0, 0).unwrap();
+
+        assert_eq!(n, 2);
+        let judged: Vec<String> = judgements(&cat)
+            .into_iter()
+            .filter(|(_, rating, _)| *rating == 2)
+            .map(|(path, _, _)| path)
+            .collect();
+        assert_eq!(judged, vec!["2026/50%_off/a.CR2", "2026/50%_off/a.jpg"]);
+    }
+
     /// A demotion has to travel. Taking the larger of the two would refuse
     /// every rating the photographer ever lowered — and lowering one is most
     /// of what a second pass over a shoot does.