Update table schema for "AffectedPath" table

Summary:
Ref T13639. Make schema changes:

  - Make repositoryID nullable, for revisions with no repository.
  - Remove "epoch", which has no readers and no clear use.
  - Change the ordering of the key, since "pathID" has more unique values and no queries ever issue without it.

Test Plan:
  - Ran `bin/storage upgrade`, got a clean schema.
  - Reindexed all revisions with an external script.
  - Reviewed index via debug UI, saw appropriate index for non-repositoy revisions.

Subscribers: PHID-OPKG-gm6ozazyms6q6i22gyam

Maniphest Tasks: T13639

Differential Revision: https://secure.phabricator.com/D21617

Author: epriestley

resources/sql/autopatches/20210315.affectedpath.01.epoch.sql

@@ -0,0 +1,2 @@
+ALTER TABLE {$NAMESPACE}_differential.differential_affectedpath
+  DROP epoch;

resources/sql/autopatches/20210315.affectedpath.02.repositoryid.sql

@@ -0,0 +1,2 @@
+ALTER TABLE {$NAMESPACE}_differential.differential_affectedpath
+  CHANGE repositoryID repositoryID INT UNSIGNED;

src/applications/differential/engine/DifferentialAffectedPathEngine.php

@@ -32,7 +32,7 @@ public function updateAffectedPaths() {
     if ($repository) {
       $repository_id = $repository->getID();
     } else {
-      return;
+      $repository_id = null;
     }
 
     $paths = $this->getAffectedPaths();
@@ -48,10 +48,9 @@ public function updateAffectedPaths() {
     foreach ($path_ids as $path_id) {
       $sql[] = qsprintf(
         $conn,
-        '(%d, %d, %d, %d)',
+        '(%nd, %d, %d)',
         $repository_id,
         $path_id,
-        PhabricatorTime::getNow(),
         $revision->getID());
     }
 
@@ -64,7 +63,7 @@ public function updateAffectedPaths() {
       foreach (PhabricatorLiskDAO::chunkSQL($sql) as $chunk) {
         queryfx(
           $conn,
-          'INSERT INTO %R (repositoryID, pathID, epoch, revisionID) VALUES %LQ',
+          'INSERT INTO %R (repositoryID, pathID, revisionID) VALUES %LQ',
           $table,
           $chunk);
       }

src/applications/differential/storage/DifferentialAffectedPath.php

@@ -8,23 +8,23 @@ final class DifferentialAffectedPath extends DifferentialDAO {
 
   protected $repositoryID;
   protected $pathID;
-  protected $epoch;
   protected $revisionID;
 
   protected function getConfiguration() {
     return array(
       self::CONFIG_TIMESTAMPS => false,
       self::CONFIG_COLUMN_SCHEMA => array(
         'id' => null,
+        'repositoryID' => 'id?',
       ),
       self::CONFIG_KEY_SCHEMA => array(
         'PRIMARY' => null,
-        'repositoryID' => array(
-          'columns' => array('repositoryID', 'pathID', 'epoch'),
-        ),
         'revisionID' => array(
           'columns' => array('revisionID'),
         ),
+        'key_path' => array(
+          'columns' => array('pathID', 'repositoryID'),
+        ),
       ),
     ) + parent::getConfiguration();
   }