fix: use initial shard encoded in primary key as most likely shard

Signed-off-by: Robin Appelman <[email protected]>

lib/private/DB/QueryBuilder/Sharded/ShardQueryRunner.php

@@ -48,14 +48,20 @@ public function getShards(bool $allShards, array $shardKeys): ?array {
 	}
 
 	/**
-	 * Try to get the shards that the keys are likely to be in, based on the shard the row was created on and caching
+	 * Try to get the shards that the keys are likely to be in, based on the shard the row was created
 	 *
 	 * @param int[] $primaryKeys
 	 * @return int[]
 	 */
 	private function getLikelyShards(array $primaryKeys): array {
-		// todo
-		return [];
+		$shards = [];
+		foreach ($primaryKeys as $primaryKey) {
+			$encodedShard = $primaryKey & ShardDefinition::PRIMARY_KEY_SHARD_MASK;
+			if (!in_array($encodedShard, $shards)) {
+				$shards[] = $encodedShard;
+			}
+		}
+		return $shards;
 	}
 
 	/**