gistfile1.clj

(defn with-lazy-results* [chunksize query func]
  (let [sql (:sql-str query)
        params (:params query)]
    (with-open [conn (.getConnection (:datasource (or (when-let [db (:db query)]
                                                        (get-connection db))
                                                      (jdbc/find-connection)
                                                      (get-connection @_default))))]
      (let [initial-autocommit (.getAutoCommit conn)]
        (try
          (.setAutoCommit conn false)
          (let [statement (jdbc/prepare-statement conn
                                                  sql
                                                  :fetch-size chunksize)]
            (jdbc/with-query-results* (apply vector statement params) func))
          (catch Exception e (throw e))
          (finally (.setAutoCommit conn initial-autocommit)))))))

(defmacro with-lazy-results [results chunksize query & body]
  `(with-lazy-results* ~chunksize (kc/query-only ~query) (fn [~results] ~@body)))