From 2bfa4f1f8c3ac454426876768c9e2dd7760266d8 Mon Sep 17 00:00:00 2001
From: Taylor Eernisse <teernisse@visiostack.com>
Date: Fri, 6 Feb 2026 22:42:26 -0500
Subject: [PATCH] perf(documents): eliminate redundant hash query in
 regeneration
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The document regenerator was making two queries per document:
1. get_existing_hash() — SELECT content_hash
2. upsert_document_inner() — SELECT id, content_hash, labels_hash, paths_hash

Query 2 already returns the content_hash needed for change detection.
Remove get_existing_hash() entirely and compute content_changed inside
upsert_document_inner() from the existing row data.

upsert_document_inner now returns Result<bool> (true = content changed)
which propagates up through upsert_document and regenerate_one,
replacing the separate pre-check. The triple-hash fast-path (all three
hashes match → return Ok(false) with no writes) is preserved.

This halves the query count for unchanged documents, which dominate
incremental syncs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 src/documents/regenerator.rs | 42 +++++++++++-------------------------
 1 file changed, 12 insertions(+), 30 deletions(-)

diff --git a/src/documents/regenerator.rs b/src/documents/regenerator.rs
index f43e15d..2a71749 100644
--- a/src/documents/regenerator.rs
+++ b/src/documents/regenerator.rs
@@ -95,38 +95,15 @@ fn regenerate_one(conn: &Connection, source_type: SourceType, source_id: i64) ->
         return Ok(true);
     };
 
-    let existing_hash = get_existing_hash(conn, source_type, source_id)?;
-    let changed = existing_hash.as_ref() != Some(&doc.content_hash);
-
-    upsert_document(conn, &doc)?;
-
-    Ok(changed)
+    upsert_document(conn, &doc)
 }
 
-fn get_existing_hash(
-    conn: &Connection,
-    source_type: SourceType,
-    source_id: i64,
-) -> Result<Option<String>> {
-    let mut stmt = conn.prepare_cached(
-        "SELECT content_hash FROM documents WHERE source_type = ?1 AND source_id = ?2",
-    )?;
-
-    let hash: Option<String> = stmt
-        .query_row(rusqlite::params![source_type.as_str(), source_id], |row| {
-            row.get(0)
-        })
-        .optional()?;
-
-    Ok(hash)
-}
-
-fn upsert_document(conn: &Connection, doc: &DocumentData) -> Result<()> {
+fn upsert_document(conn: &Connection, doc: &DocumentData) -> Result<bool> {
     conn.execute_batch("SAVEPOINT upsert_doc")?;
     match upsert_document_inner(conn, doc) {
-        Ok(()) => {
+        Ok(changed) => {
             conn.execute_batch("RELEASE upsert_doc")?;
-            Ok(())
+            Ok(changed)
         }
         Err(e) => {
             let _ = conn.execute_batch("ROLLBACK TO upsert_doc; RELEASE upsert_doc");
@@ -135,7 +112,7 @@ fn upsert_document(conn: &Connection, doc: &DocumentData) -> Result<()> {
     }
 }
 
-fn upsert_document_inner(conn: &Connection, doc: &DocumentData) -> Result<()> {
+fn upsert_document_inner(conn: &Connection, doc: &DocumentData) -> Result<bool> {
     let existing: Option<(i64, String, String, String)> = conn
         .query_row(
             "SELECT id, content_hash, labels_hash, paths_hash FROM documents
@@ -145,12 +122,17 @@ fn upsert_document_inner(conn: &Connection, doc: &DocumentData) -> Result<()> {
         )
         .optional()?;
 
+    let content_changed = match &existing {
+        Some((_, old_content_hash, _, _)) => old_content_hash != &doc.content_hash,
+        None => true,
+    };
+
     if let Some((_, ref old_content_hash, ref old_labels_hash, ref old_paths_hash)) = existing
         && old_content_hash == &doc.content_hash
         && old_labels_hash == &doc.labels_hash
         && old_paths_hash == &doc.paths_hash
     {
-        return Ok(());
+        return Ok(false);
     }
 
     let labels_json = serde_json::to_string(&doc.labels).unwrap_or_else(|_| "[]".to_string());
@@ -260,7 +242,7 @@ fn upsert_document_inner(conn: &Connection, doc: &DocumentData) -> Result<()> {
         }
     }
 
-    Ok(())
+    Ok(content_changed)
 }
 
 fn delete_document(conn: &Connection, source_type: SourceType, source_id: i64) -> Result<()> {