[4.4] Add database configuration option for "sql_big_selects" session variable on MySQL or MariaDB databases

administrator/components/com_config/forms/application.xml

@@ -279,6 +279,20 @@
 			showon="dbtype:mysql,mysqli[AND]dbencryption:2"
 		/>
 
+		<field
+			name="dbsqlbigselects"
+			type="list"
+			label="COM_CONFIG_FIELD_DATABASE_SQL_BIG_SELECTS_LABEL"
+			default="0"
+			showon="dbtype:mysql,mysqli"
+			filter="integer"
+			validate="options"
+			>
+			<option value="0">COM_CONFIG_FIELD_DATABASE_SQL_BIG_SELECTS_VALUE_NONE</option>
+			<option value="1">JNO</option>
+			<option value="2">JYES</option>
+		</field>
+
 	</fieldset>
 
 	<fieldset

administrator/language/en-GB/com_config.ini

@@ -59,6 +59,8 @@ COM_CONFIG_FIELD_DATABASE_NAME_LABEL="Database Name"
 COM_CONFIG_FIELD_DATABASE_PASSWORD_DESC="Do not edit this field unless absolutely necessary (eg after the transfer of the database to a new hosting provider)."
 COM_CONFIG_FIELD_DATABASE_PASSWORD_LABEL="Database Password"
 COM_CONFIG_FIELD_DATABASE_PREFIX_LABEL="Database Tables Prefix"
+COM_CONFIG_FIELD_DATABASE_SQL_BIG_SELECTS_LABEL="Allow large queries"
+COM_CONFIG_FIELD_DATABASE_SQL_BIG_SELECTS_VALUE_NONE="No change (server controlled)"
 COM_CONFIG_FIELD_DATABASE_TYPE_DESC="Do not change this to a different database technology e.g. from MySQLi (MySQL database technology) to PostgreSQL (Postgres database technology); it will break your site."
 COM_CONFIG_FIELD_DATABASE_TYPE_LABEL="Database Type"
 COM_CONFIG_FIELD_DATABASE_USERNAME_LABEL="Database Username"

installation/configuration.php-dist

@@ -50,6 +50,7 @@ class JConfig
 	public $dbsslcert = '';
 	public $dbsslca = '';
 	public $dbsslcipher = '';
+	public $dbsqlbigselects = 0;
 
 	/* Server Settings */
 	public $secret = '';     // Use something very secure. For example on linux the following command `cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w ${1:-16} | head -n 1`

libraries/src/Factory.php

@@ -677,6 +677,16 @@ protected static function createDbo()
             }
         }
 
+        // Set sql_big_selects variable for mysql adapters
+        if (in_array($conf->get('dbtype'), ['mysql', 'mysqli'])) {
+            $sqlbigselects = (int) $conf->get('dbsqlbigselects');
+
+            // Only set option if enforced by configuration
+            if ($sqlbigselects !== 0) {
+                $options['sqlBigSelects'] = $sqlbigselects === 2;
+            }
+        }
+
         try {
             $db = DatabaseDriver::getInstance($options);
         } catch (\RuntimeException $e) {

libraries/src/Service/Provider/Database.php

@@ -115,6 +115,16 @@ function (Container $container) {
                         $options['charset'] = 'utf8mb4';
                     }
 
+                    // Set sql_big_selects variable for mysql adapters
+                    if (in_array(strtolower($dbtype), ['mysql', 'mysqli'])) {
+                        $sqlbigselects = (int) $conf->get('dbsqlbigselects');
+
+                        // Only set option if enforced by configuration
+                        if ($sqlbigselects !== 0) {
+                            $options['sqlBigSelects'] = $sqlbigselects === 2;
+                        }
+                    }
+
                     if (JDEBUG) {
                         $options['monitor'] = new \Joomla\Database\Monitor\DebugMonitor();
                     }