diff --git a/src/applications/diffusion/query/DiffusionCommitQuery.php b/src/applications/diffusion/query/DiffusionCommitQuery.php
index e8f499955a..ec76468332 100644
--- a/src/applications/diffusion/query/DiffusionCommitQuery.php
+++ b/src/applications/diffusion/query/DiffusionCommitQuery.php
@@ -51,6 +51,11 @@ final class DiffusionCommitQuery
    * they queried for.
    */
   public function withIdentifiers(array $identifiers) {
+    // Some workflows (like blame lookups) can pass in large numbers of
+    // duplicate identifiers. We only care about unique identifiers, so
+    // get rid of duplicates immediately.
+    $identifiers = array_fuse($identifiers);
+
     $this->identifiers = $identifiers;
     return $this;
   }
@@ -185,7 +190,7 @@ final class DiffusionCommitQuery
 
       // Build the identifierMap
       if ($this->identifiers !== null) {
-        $ids = array_fuse($this->identifiers);
+        $ids = $this->identifiers;
         $prefixes = array(
           'r'.$commit->getRepository()->getCallsign(),
           'r'.$commit->getRepository()->getCallsign().':',
@@ -395,7 +400,6 @@ final class DiffusionCommitQuery
         $repos->execute();
 
         $repos = $repos->getIdentifierMap();
-
         foreach ($refs as $key => $ref) {
           $repo = idx($repos, $ref['callsign']);
 
@@ -404,7 +408,7 @@ final class DiffusionCommitQuery
           }
 
           if ($repo->isSVN()) {
-            if (!ctype_digit($ref['identifier'])) {
+            if (!ctype_digit((string)$ref['identifier'])) {
               continue;
             }
             $sql[] = qsprintf(
@@ -419,11 +423,25 @@ final class DiffusionCommitQuery
             if (strlen($ref['identifier']) < $min_qualified) {
               continue;
             }
-            $sql[] = qsprintf(
-              $conn,
-              '(commit.repositoryID = %d AND commit.commitIdentifier LIKE %>)',
-              $repo->getID(),
-              $ref['identifier']);
+
+            $identifier = $ref['identifier'];
+            if (strlen($identifier) == 40) {
+              // MySQL seems to do slightly better with this version if the
+              // clause, so issue it if we have a full commit hash.
+              $sql[] = qsprintf(
+                $conn,
+                '(commit.repositoryID = %d
+                  AND commit.commitIdentifier = %s)',
+                $repo->getID(),
+                $identifier);
+            } else {
+              $sql[] = qsprintf(
+                $conn,
+                '(commit.repositoryID = %d
+                  AND commit.commitIdentifier LIKE %>)',
+                $repo->getID(),
+                $identifier);
+            }
           }
         }
       }