MDL-68164 dml: Cache postgres field type metadata in MUC

lib/dml/pgsql_native_moodle_database.php

@@ -946,6 +946,37 @@ public function close_cursor($cursorname) {
         return true;
     }
 
+    /**
+     * A faster version of pg_field_type
+     *
+     * The pg_field_type function in the php postgres driver internally makes an sql call
+     * to get the list of field types which it statically caches only for a single request.
+     * This wraps it in a cache keyed by oid to avoid these DB calls on every request.
+     *
+     * @param resource $result
+     * @param int $fieldnumber
+     * @return string Field type
+     */
+    public function pg_field_type($result, int $fieldnumber) {
+        static $map;
+        $cache = $this->get_metacache();
+
+        // Getting the oid doesn't make an internal query.
+        $oid = pg_field_type_oid($result, $fieldnumber);
+        if (!$map) {
+            $map = $cache->get('oid2typname');
+        }
+        if ($map === false) {
+            $map = [];
+        }
+        if (isset($map[$oid])) {
+            return $map[$oid];
+        }
+        $map[$oid] = pg_field_type($result, $fieldnumber);
+        $cache->set('oid2typname', $map);
+        return $map[$oid];
+    }
+
     /**
      * Get a number of records as an array of objects using a SQL statement.
      *
@@ -980,7 +1011,7 @@ public function get_records_sql($sql, array $params = null, $limitfrom = 0, $lim
         $numfields = pg_num_fields($result);
         $blobs = array();
         for ($i = 0; $i < $numfields; $i++) {
-            $type = pg_field_type($result, $i);
+            $type = $this->pg_field_type($result, $i);
             if ($type == 'bytea') {
                 $blobs[] = pg_field_name($result, $i);
             }
@@ -1021,7 +1052,7 @@ public function get_fieldset_sql($sql, array $params=null) {
 
         $return = pg_fetch_all_columns($result, 0);
 
-        if (pg_field_type($result, 0) == 'bytea') {
+        if ($this->pg_field_type($result, 0) == 'bytea') {
             foreach ($return as $key => $value) {
                 $return[$key] = ($value === null ? $value : pg_unescape_bytea($value));
             }

lib/dml/pgsql_native_moodle_recordset.php

@@ -74,7 +74,7 @@ public function __construct($result, pgsql_native_moodle_database $db = null, $c
         // Find out if there are any blobs.
         $numfields = pg_num_fields($this->result);
         for ($i = 0; $i < $numfields; $i++) {
-            $type = pg_field_type($this->result, $i);
+            $type = $this->db->pg_field_type($this->result, $i);
             if ($type == 'bytea') {
                 $this->blobs[] = pg_field_name($this->result, $i);
             }

lib/dml/tests/dml_test.php

@@ -17,15 +17,23 @@
 /**
  * DML layer tests.
  *
- * @package    core_dml
- * @category   phpunit
+ * @package    core
+ * @subpackage dml
  * @copyright  2008 Nicolas Connault
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
 defined('MOODLE_INTERNAL') || die();
 
-class core_dml_testcase extends database_driver_testcase {
+/**
+ * DML layer tests.
+ *
+ * @package    core
+ * @subpackage dml
+ * @copyright  2008 Nicolas Connault
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class dml_test extends database_driver_testcase {
 
     protected function setUp(): void {
         parent::setUp();
@@ -493,7 +501,7 @@ public function test_add_sql_debugging() {
 -- line 74 of /lib/dml/tests/fixtures/test_dml_sql_debugging_fixture.php: call to test_dml_sql_debugging_fixture->one()
 -- line 83 of /lib/dml/tests/fixtures/test_dml_sql_debugging_fixture.php: call to test_dml_sql_debugging_fixture->two()
 -- line 92 of /lib/dml/tests/fixtures/test_dml_sql_debugging_fixture.php: call to test_dml_sql_debugging_fixture->three()
--- line 489 of /lib/dml/tests/dml_test.php: call to test_dml_sql_debugging_fixture->four()
+-- line 497 of /lib/dml/tests/dml_test.php: call to test_dml_sql_debugging_fixture->four()
 EOD;
         $this->assertEquals($this->unix_to_os_dirsep($expected), $out);
 

lib/dml/tests/pgsql_native_moodle_database_test.php

@@ -32,7 +32,7 @@
  * @copyright 2020 Ruslan Kabalin
  * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
-class pgsql_native_moodle_database_testcase extends advanced_testcase {
+class pgsql_native_moodle_database_test extends advanced_testcase {
 
     /**
      * Setup before class.

lib/dml/tests/pgsql_native_recordset_test.php

@@ -36,7 +36,7 @@
  * @copyright 2017 The Open University
  * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
-class pgsql_native_recordset_testcase extends basic_testcase {
+class pgsql_native_recordset_test extends basic_testcase {
 
     /** @var pgsql_native_moodle_database Special database connection */
     protected $specialdb;

lib/upgrade.txt

@@ -69,6 +69,8 @@ information provided here is intended especially for developers.
   rendered. The default icon for "select" types has also changed to a dropdown caret ("t/expanded").
 * The function message_send() in messagelib.php now returns false if there is an error sending the message to the
   message processor (MDL-70046).
+* The postgres driver now wraps calls to pg_field_type() and caches them in databasemeta to save an invisible internal
+  DB call on every request.
 
 === 3.11.2 ===
 * For security reasons, filelib has been updated so all requests now use emulated redirects.