MDL-14974 improved columns caching implementation

lib/dml/adodb_moodle_database.php

@@ -10,7 +10,6 @@ require_once($CFG->libdir.'/dml/adodb_moodle_recordset.php');
 abstract class adodb_moodle_database extends moodle_database {
 
     protected $db;
-    protected $columns = array(); // I wish we had a shared memory cache for this :-(
 
     /**
      * Returns localised database type name
@@ -137,8 +136,8 @@ abstract class adodb_moodle_database extends moodle_database {
         return $indexes;
     }
 
-    public function get_columns($table) {
-        if (isset($this->columns[$table])) {
+    public function get_columns($table, $usecache=true) {
+        if ($usecache and isset($this->columns[$table])) {
             return $this->columns[$table];
         }
 
@@ -157,14 +156,6 @@ abstract class adodb_moodle_database extends moodle_database {
         return $this->columns[$table];
     }
 
-    public function reset_columns($table=null) {
-        if ($table) {
-            unset($this->columns[$table]);
-        } else {
-            $this->columns[$table] = array();
-        }
-    }
-
     public function get_last_error() {
         return $this->db->ErrorMsg();
     }
@@ -206,6 +197,8 @@ abstract class adodb_moodle_database extends moodle_database {
             $result = false;
             $this->report_error($sql);
         }
+        // structure changed, reset columns cache
+        $this->reset_columns();
         return $result;
     }
 

lib/dml/moodle_database.php

@@ -9,6 +9,8 @@ abstract class moodle_database {
     // manipulates the db structure
     protected $database_manager;
 
+    protected $columns = array(); // I wish we had a shared memory cache for this :-(
+
     // db connection options
     protected $dbhost;
     protected $dbuser;
@@ -319,16 +321,19 @@ abstract class moodle_database {
     /**
      * Returns datailed information about columns in table. This information is cached internally.
      * @param string $table name
+     * @param bool $usecache
      * @return array array of database_column_info objects indexed with column names
      */
-    public abstract function get_columns($table);
+    public abstract function get_columns($table, $usecache=true);
 
     /**
      * Reset internal column details cache
      * @param string $table - empty means all, or one if name of table given
      * @return void
      */
-    public abstract function reset_columns($table=null);
+    public function reset_columns() {
+        $this->columns[] = array();
+    }
 
     /**
      * Returns sql generator used for db manipulation.

lib/dml/pdo_moodle_database.php

@@ -10,7 +10,6 @@ require_once($CFG->libdir.'/dml/pdo_moodle_recordset.php');
 abstract class pdo_moodle_database extends moodle_database {
 
     protected $pdb;
-    protected $columns = array(); // I wish we had a shared memory cache for this :-(
 
     //TODO: This looks incorrect now IMO. Construct should have only external and connect get all the rest of params
     public function __construct($dbhost, $dbuser, $dbpass, $dbname, $dbpersist, $prefix, array $dboptions=null, $external=false) {
@@ -31,8 +30,8 @@ abstract class pdo_moodle_database extends moodle_database {
     protected function configure_dbconnection() {
     }
 
-    public function get_columns($table) {
-        if (isset($this->columns[$table])) {
+    public function get_columns($table, $usecache=true) {
+        if ($usecache and isset($this->columns[$table])) {
             return $this->columns[$table];
         }
 
@@ -43,15 +42,6 @@ abstract class pdo_moodle_database extends moodle_database {
         return $this->columns[$table];
     }
 
-    public function reset_columns($table=null) {
-        if ($table) {
-            unset($this->columns[$table]);
-        } else {
-            $this->columns[$table] = array();
-        }
-    }
-
-
     protected function report_error($sql, $params, $obj) {
         debugging($e->getMessage() .'<br /><br />'. s($sql));
     }
@@ -66,7 +56,6 @@ abstract class pdo_moodle_database extends moodle_database {
 
     public function execute($sql, array $params=null) {
         try {
-            //$this->reset_columns(); // TODO: do we need to clean the cache here??
             list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
             $sth = $this->dbh->prepare($sql);
             return $sth->execute($params);

lib/dml/postgres7_adodb_moodle_database.php

@@ -100,8 +100,8 @@ class postgres7_adodb_moodle_database extends adodb_moodle_database {
         return SQL_PARAMS_QM;
     }
 
-    public function get_columns($table) {
-        if (isset($this->columns[$table])) {
+    public function get_columns($table, $usecache=true) {
+        if ($usecache and isset($this->columns[$table])) {
             return $this->columns[$table];
         }