MDL-34271 use the same collation when adding new tables or columns

lib/ddl/mysql_sql_generator.php

@@ -119,6 +119,9 @@ public function getResetSequenceSQL($table) {
     public function getCreateTableSQL($xmldb_table) {
         // First find out if want some special db engine.
         $engine = $this->mdb->get_dbengine();
+        // Do we know collation?
+        $collation = $this->mdb->get_dbcollation();
+
         $sqlarr = parent::getCreateTableSQL($xmldb_table);
 
         // Let's inject the extra MySQL tweaks.
@@ -127,6 +130,12 @@ public function getCreateTableSQL($xmldb_table) {
                 if ($engine) {
                     $sqlarr[$i] .= " ENGINE = $engine";
                 }
+                if ($collation) {
+                    if (strpos($collation, 'utf8_') === 0) {
+                        $sqlarr[$i] .= " DEFAULT CHARACTER SET utf8";
+                    }
+                    $sqlarr[$i] .= " DEFAULT COLLATE = $collation";
+                }
             }
         }
 
@@ -141,9 +150,26 @@ public function getCreateTableSQL($xmldb_table) {
      * @return array of sql statements
      */
     public function getCreateTempTableSQL($xmldb_table) {
+        // Do we know collation?
+        $collation = $this->mdb->get_dbcollation();
         $this->temptables->add_temptable($xmldb_table->getName());
-        $sqlarr = parent::getCreateTableSQL($xmldb_table); // we do not want the engine hack included in create table SQL
-        $sqlarr = preg_replace('/^CREATE TABLE (.*)/s', 'CREATE TEMPORARY TABLE $1', $sqlarr);
+
+        $sqlarr = parent::getCreateTableSQL($xmldb_table);
+
+        // Let's inject the extra MySQL tweaks.
+        foreach ($sqlarr as $i=>$sql) {
+            if (strpos($sql, 'CREATE TABLE ') === 0) {
+                // We do not want the engine hack included in create table SQL.
+                $sqlarr[$i] = preg_replace('/^CREATE TABLE (.*)/s', 'CREATE TEMPORARY TABLE $1', $sql);
+                if ($collation) {
+                    if (strpos($collation, 'utf8_') === 0) {
+                        $sqlarr[$i] .= " DEFAULT CHARACTER SET utf8";
+                    }
+                    $sqlarr[$i] .= " DEFAULT COLLATE $collation";
+                }
+            }
+        }
+
         return $sqlarr;
     }
 
@@ -224,9 +250,21 @@ public function getTypeSQL($xmldb_type, $xmldb_length=null, $xmldb_decimals=null
                     $xmldb_length='255';
                 }
                 $dbtype .= '(' . $xmldb_length . ')';
+                if ($collation = $this->mdb->get_dbcollation()) {
+                    if (strpos($collation, 'utf8_') === 0) {
+                        $dbtype .= " CHARACTER SET utf8";
+                    }
+                    $dbtype .= " COLLATE $collation";
+                }
                 break;
             case XMLDB_TYPE_TEXT:
                 $dbtype = 'LONGTEXT';
+                if ($collation = $this->mdb->get_dbcollation()) {
+                    if (strpos($collation, 'utf8_') === 0) {
+                        $dbtype .= " CHARACTER SET utf8";
+                    }
+                    $dbtype .= " COLLATE $collation";
+                }
                 break;
             case XMLDB_TYPE_BINARY:
                 $dbtype = 'LONGBLOB';

lib/dml/mysqli_native_moodle_database.php

@@ -82,7 +82,13 @@ public function create_database($dbhost, $dbuser, $dbpass, $dbname, array $dbopt
             throw new dml_connection_exception($dberr);
         }
 
-        $result = $conn->query("CREATE DATABASE $dbname DEFAULT CHARACTER SET utf8 COLLATE utf8_unicode_ci");
+        if (isset($dboptions['dbcollation']) and strpos($dboptions['dbcollation'], 'utf8_') === 0) {
+            $collation = $dboptions['dbcollation'];
+        } else {
+            $collation = 'utf8_unicode_ci';
+        }
+
+        $result = $conn->query("CREATE DATABASE $dbname DEFAULT CHARACTER SET utf8 DEFAULT COLLATE ".$collation);
 
         $conn->close();
 
@@ -207,6 +213,72 @@ public function get_dbengine() {
         return $engine;
     }
 
+    /**
+     * Returns the current MySQL db collation.
+     *
+     * This is an ugly workaround for MySQL default collation problems.
+     *
+     * @return string or null MySQL collation name
+     */
+    public function get_dbcollation() {
+        if (isset($this->dboptions['dbcollation'])) {
+            return $this->dboptions['dbcollation'];
+        }
+        if ($this->external) {
+            return null;
+        }
+
+        $collation = null;
+
+        // Look for current collation of our config table (the first table that gets created),
+        // so that we create all tables with the same collation.
+        $sql = "SELECT collation_name
+                  FROM INFORMATION_SCHEMA.COLUMNS
+                 WHERE table_schema = DATABASE() AND table_name = '{$this->prefix}config' AND column_name = 'value'";
+        $this->query_start($sql, NULL, SQL_QUERY_AUX);
+        $result = $this->mysqli->query($sql);
+        $this->query_end($result);
+        if ($rec = $result->fetch_assoc()) {
+            $collation = $rec['collation_name'];
+        }
+        $result->close();
+
+        if (!$collation) {
+            // Get the default database collation, but only if using UTF-8.
+            $sql = "SELECT @@collation_database";
+            $this->query_start($sql, NULL, SQL_QUERY_AUX);
+            $result = $this->mysqli->query($sql);
+            $this->query_end($result);
+            if ($rec = $result->fetch_assoc()) {
+                if (strpos($rec['@@collation_database'], 'utf8_') === 0) {
+                    $collation = $rec['@@collation_database'];
+                }
+            }
+            $result->close();
+        }
+
+        if (!$collation) {
+            // We want only utf8 compatible collations.
+            $collation = null;
+            $sql = "SHOW COLLATION WHERE Collation LIKE 'utf8\_%' AND Charset = 'utf8'";
+            $this->query_start($sql, NULL, SQL_QUERY_AUX);
+            $result = $this->mysqli->query($sql);
+            $this->query_end($result);
+            while ($res = $result->fetch_assoc()) {
+                $collation = $res['Collation'];
+                if (strtoupper($res['Default']) === 'YES') {
+                    $collation = $res['Collation'];
+                    break;
+                }
+            }
+            $result->close();
+        }
+
+        // Cache the result to improve performance.
+        $this->dboptions['dbcollation'] = $collation;
+        return $collation;
+    }
+
     /**
      * Returns localised database type name
      * Note: can be used before connect()