diff --git a/core/translate/emitter.rs b/core/translate/emitter.rs
index 8e3e2c81e..67c8695de 100644
--- a/core/translate/emitter.rs
+++ b/core/translate/emitter.rs
@@ -1194,6 +1194,7 @@ fn emit_update_insns(
                 extra_amount: 0,
             });
         }
+        // last register is the rowid
         program.emit_insn(Insn::Copy {
             src_reg: rowid_reg,
             dst_reg: idx_start_reg + num_cols,
@@ -1209,8 +1210,9 @@ fn emit_update_insns(
         });
 
         // Handle unique constraint
-        if index.unique {
+        if !index.unique {
             let constraint_check = program.allocate_label();
+            // check if the record already exists in the index for unique indexes and abort if so
             program.emit_insn(Insn::NoConflict {
                 cursor_id: *idx_cursor_id,
                 target_pc: constraint_check,
@@ -1224,6 +1226,7 @@ fn emit_update_insns(
                 dest: idx_rowid_reg,
             });
 
+            // Skip over the UNIQUE constraint failure if the existing row is the one that we are currently changing
             program.emit_insn(Insn::Eq {
                 lhs: beg,
                 rhs: idx_rowid_reg,
@@ -1232,12 +1235,18 @@ fn emit_update_insns(
                 collation: program.curr_collation(),
             });
 
-            let column_names = index
-                .columns
-                .iter()
-                .map(|c| format!("{}.{}", table_ref.table.get_name(), c.name))
-                .collect::<Vec<_>>()
-                .join(", ");
+            let column_names = index.columns.iter().enumerate().fold(
+                String::with_capacity(50),
+                |mut accum, (idx, col)| {
+                    if idx > 0 {
+                        accum.push_str(", ");
+                    }
+                    accum.push_str(table_ref.table.get_name());
+                    accum.push('.');
+                    accum.push_str(&col.name);
+                    accum
+                },
+            );
 
             program.emit_insn(Insn::Halt {
                 err_code: SQLITE_CONSTRAINT_PRIMARYKEY,
diff --git a/core/translate/update.rs b/core/translate/update.rs
index 14d5f46d2..8f565b630 100644
--- a/core/translate/update.rs
+++ b/core/translate/update.rs
@@ -379,7 +379,8 @@ pub fn prepare_update_plan(
         // If the rowid alias is used in the SET clause, we need to update all indexes
         indexes.to_vec()
     } else {
-        // otherwise we need to update the indexes whose columns are set in the SET clause
+        // otherwise we need to update the indexes whose columns are set in the SET clause,
+        // or if the colunns used in the partial index WHERE clause are being updated
         indexes
             .iter()
             .filter_map(|idx| {
@@ -390,20 +391,20 @@ pub fn prepare_update_plan(
 
                 if !needs {
                     if let Some(w) = &idx.where_clause {
-                        // Bind once so names→positions are resolved exactly like execution.
                         let mut where_copy = w.as_ref().clone();
                         let mut param = ParamState::disallow();
                         let mut tr =
                             TableReferences::new(table_references.joined_tables().to_vec(), vec![]);
-                        bind_and_rewrite_expr(
+                        let _ = bind_and_rewrite_expr(
                             &mut where_copy,
                             Some(&mut tr),
                             None,
                             connection,
                             &mut param,
-                        )
-                        .expect("bind where");
+                        );
                         let cols_used = collect_cols_used_in_expr(&where_copy);
+                        // if any of the columns used in the partial index WHERE clause is being
+                        // updated, we need to update this index
                         needs = cols_used.iter().any(|c| updated_cols.contains(c));
                     }
                 }