ALTER TABLE execution_logs ADD COLUMN attempt INT DEFAULT 0;
ALTER TABLE execution_logs ADD COLUMN upload_time BIGINT DEFAULT 1420099200000;
UPDATE execution_logs SET upload_time=(UNIX_TIMESTAMP()*1000) WHERE upload_time=1420099200000;

ALTER TABLE execution_logs ADD PRIMARY KEY(exec_id, name, attempt, start_byte);
ALTER TABLE execution_logs ADD INDEX ex_log_attempt (exec_id, name, attempt);
