Set `useLocalSessionState=true` for MySQL DW connections [PERFORMANCE BOOST] (#44509)

* Set `useLocalSessionState=true` for MySQL DW connections

* Fix GH issue number

* Test fixes 

* Lint fix 

src/metabase/driver/mysql.clj

@@ -522,7 +522,14 @@
    :characterEncoding    "UTF8"
    :characterSetResults  "UTF8"
    ;; GZIP compress packets sent between Metabase server and MySQL/MariaDB database
-   :useCompression       true})
+   :useCompression       true
+   ;; record transaction isolation level and auto-commit locally, and avoid hitting the DB if we do something like
+   ;; `.setTransactionIsolation()` to something we previously set it to. Since we do this every time we run a
+   ;; query (see [[metabase.driver.sql-jdbc.execute/set-best-transaction-level!]]) this should speed up things a bit by
+   ;; removing that overhead. See also
+   ;; https://dev.mysql.com/doc/connector-j/en/connector-j-connp-props-performance-extensions.html#cj-conn-prop_useLocalSessionState
+   ;; and #44507
+   :useLocalSessionState true})
 
 (defn- maybe-add-program-name-option [jdbc-spec additional-options-map]
   ;; connectionAttributes (if multiple) are separated by commas, so values that contain spaces are OK, so long as they

test/metabase/driver/mysql_test.clj

-(ns metabase.driver.mysql-test
+(ns ^:mb/once metabase.driver.mysql-test
   (:require
    [clojure.java.jdbc :as jdbc]
    [clojure.string :as str]
    [clojure.test :refer :all]
    [honey.sql :as sql]
    [metabase.actions.error :as actions.error]
-   [metabase.config :as config]
    [metabase.db.metadata-queries :as metadata-queries]
    [metabase.driver :as driver]
    [metabase.driver.mysql :as mysql]
@@ -255,45 +254,35 @@
 (def ^:private sample-connection-details
   {:db "my_db", :host "localhost", :port "3306", :user "cam", :password "bad-password"})
 
-(def ^:private sample-jdbc-spec
-  {:password             "bad-password"
-   :characterSetResults  "UTF8"
-   :characterEncoding    "UTF8"
-   :classname            "org.mariadb.jdbc.Driver"
-   :subprotocol          "mysql"
-   :zeroDateTimeBehavior "convertToNull"
-   :user                 "cam"
-   :subname              "//localhost:3306/my_db"
-   :connectionAttributes (str "program_name:" config/mb-version-and-process-identifier)
-   :useCompression       true
-   :useUnicode           true})
-
-(deftest connection-spec-test
+(deftest ^:parallel connection-spec-test
   (testing "Do `:ssl` connection details give us the connection spec we'd expect?"
-    (is (= (assoc sample-jdbc-spec :useSSL true :serverSslCert "sslCert")
-           (sql-jdbc.conn/connection-details->spec :mysql (assoc sample-connection-details :ssl      true
-                                                                                           :ssl-cert "sslCert")))))
+    (is (=? {:useSSL true, :serverSslCert "sslCert"}
+            (sql-jdbc.conn/connection-details->spec :mysql (assoc sample-connection-details :ssl      true
+                                                                  :ssl-cert "sslCert"))))))
 
+(deftest ^:parallel connection-spec-test-2
   (testing "what about non-SSL connections?"
-    (is (= (assoc sample-jdbc-spec :useSSL false)
-           (sql-jdbc.conn/connection-details->spec :mysql sample-connection-details))))
+    (is (=? {:useSSL false}
+            (sql-jdbc.conn/connection-details->spec :mysql sample-connection-details)))))
 
+(deftest ^:parallel connection-spec-test-3
   (testing "Connections that are `:ssl false` but with `useSSL` in the additional options should be treated as SSL (see #9629)"
-    (is (= (assoc sample-jdbc-spec :useSSL  true
-                                   :subname "//localhost:3306/my_db?useSSL=true&trustServerCertificate=true")
-           (sql-jdbc.conn/connection-details->spec :mysql
-             (assoc sample-connection-details
-                    :ssl false
-                    :additional-options "useSSL=true&trustServerCertificate=true")))))
+    (is (=? {:useSSL true, :subname "//localhost:3306/my_db?useSSL=true&trustServerCertificate=true"}
+            (sql-jdbc.conn/connection-details->spec :mysql
+                                                    (assoc sample-connection-details
+                                                           :ssl false
+                                                           :additional-options "useSSL=true&trustServerCertificate=true"))))))
+
+(deftest ^:parallel connection-spec-test-4
   (testing "A program_name specified in additional-options is not overwritten by us"
     (let [conn-attrs "connectionAttributes=program_name:my_custom_value"]
-      (is (= (-> sample-jdbc-spec
-                 (assoc :subname (str "//localhost:3306/my_db?" conn-attrs), :useSSL false)
-                 ;; because program_name was in additional-options, we shouldn't use emit :connectionAttributes
-                 (dissoc :connectionAttributes))
-             (sql-jdbc.conn/connection-details->spec
-              :mysql
-              (assoc sample-connection-details :additional-options conn-attrs)))))))
+      (is (=? {:subname (str "//localhost:3306/my_db?" conn-attrs)
+               :useSSL false
+               ;; because program_name was in additional-options, we shouldn't use emit :connectionAttributes
+               :connectionAttributes (symbol "nil #_\"key is not present.\"")}
+              (sql-jdbc.conn/connection-details->spec
+               :mysql
+               (assoc sample-connection-details :additional-options conn-attrs)))))))
 
 (deftest read-timediffs-test
   (mt/test-driver :mysql