I'm seeing this stack trace right now, having just pushed some tags into a hosted git repo:
[2014-10-20 15:09:40] PHLOG: 'Unable to index document PHID-CMIT-rrzk2z5yfad5i7b32bm3 with engine PhabricatorSearchEngineMySQL.' at [/home/aob01/phabricator/phabricator/src/applications/search/index/PhabricatorSearchDocumentIndexer.php:57]
#0 phlog(string) called at [<phabricator>/src/applications/search/index/PhabricatorSearchDocumentIndexer.php:57] #1 PhabricatorSearchDocumentIndexer::indexDocumentByPHID(string) called at [<phabricator>/src/applications/search/index/PhabricatorSearchIndexer.php:21] #2 PhabricatorSearchIndexer::indexDocumentByPHID(string) called at [<phabricator>/src/applications/search/worker/PhabricatorSearchWorker.php:10] #3 PhabricatorSearchWorker::doWork() called at [<phabricator>/src/infrastructure/daemon/workers/PhabricatorWorker.php:87] #4 PhabricatorWorker::executeTask() called at [<phabricator>/src/infrastructure/daemon/workers/storage/PhabricatorWorkerActiveTask.php:124] #5 PhabricatorWorkerActiveTask::executeTask() called at [<phabricator>/src/infrastructure/daemon/workers/PhabricatorTaskmasterDaemon.php:19] #6 PhabricatorTaskmasterDaemon::run() called at [<phutil>/src/daemon/PhutilDaemon.php:91] #7 PhutilDaemon::execute() called at [<phutil>/scripts/daemon/exec/exec_daemon.php:111]
[2014-10-20 15:09:40] EXCEPTION: (AphrontQueryException) #126: Incorrect key file for table './phabricator_search/search_documentfield.MYI'; try to repair it at [<phutil>/src/aphront/storage/connection/mysql/AphrontMySQLDatabaseConnectionBase.php:308]
#0 phlog(AphrontQueryException) called at [<phabricator>/src/applications/search/index/PhabricatorSearchDocumentIndexer.php:58] #1 PhabricatorSearchDocumentIndexer::indexDocumentByPHID(string) called at [<phabricator>/src/applications/search/index/PhabricatorSearchIndexer.php:21] #2 PhabricatorSearchIndexer::indexDocumentByPHID(string) called at [<phabricator>/src/applications/search/worker/PhabricatorSearchWorker.php:10] #3 PhabricatorSearchWorker::doWork() called at [<phabricator>/src/infrastructure/daemon/workers/PhabricatorWorker.php:87] #4 PhabricatorWorker::executeTask() called at [<phabricator>/src/infrastructure/daemon/workers/storage/PhabricatorWorkerActiveTask.php:124] #5 PhabricatorWorkerActiveTask::executeTask() called at [<phabricator>/src/infrastructure/daemon/workers/PhabricatorTaskmasterDaemon.php:19] #6 PhabricatorTaskmasterDaemon::run() called at [<phutil>/src/daemon/PhutilDaemon.php:91] #7 PhutilDaemon::execute() called at [<phutil>/scripts/daemon/exec/exec_daemon.php:111]