moodle/lib/xmldb/xmldb_index.php

349 lines
12 KiB
PHP

<?php
///////////////////////////////////////////////////////////////////////////
// //
// NOTICE OF COPYRIGHT //
// //
// Moodle - Modular Object-Oriented Dynamic Learning Environment //
// http://moodle.com //
// //
// Copyright (C) 1999 onwards Martin Dougiamas http://dougiamas.com //
// (C) 2001-3001 Eloy Lafuente (stronk7) http://contiento.com //
// //
// This program is free software; you can redistribute it and/or modify //
// it under the terms of the GNU General Public License as published by //
// the Free Software Foundation; either version 2 of the License, or //
// (at your option) any later version. //
// //
// This program is distributed in the hope that it will be useful, //
// but WITHOUT ANY WARRANTY; without even the implied warranty of //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
// GNU General Public License for more details: //
// //
// http://www.gnu.org/copyleft/gpl.html //
// //
///////////////////////////////////////////////////////////////////////////
/// This class represent one XMLDB Index
class xmldb_index extends xmldb_object {
var $unique;
var $fields;
/**
* Note:
* - MySQL: MyISAM has a limit of 1000 bytes for any key including composed, InnoDB has limit 3500 bytes.
*
* @const max length of composed indexes, one utf-8 char is 3 bytes in the worst case
*/
const INDEX_COMPOSED_MAX_BYTES = 999;
/**
* Note:
* - MySQL: InnoDB limits size of index on single column to 767bytes (256 chars)
*
* @const single column index length limit, one utf-8 char is 3 bytes in the worst case
*/
const INDEX_MAX_BYTES = 765;
/**
* Creates one new xmldb_index
*/
function __construct($name, $type=null, $fields=array()) {
$this->unique = false;
$this->fields = array();
parent::__construct($name);
return $this->set_attributes($type, $fields);
}
/**
* Set all the attributes of one xmldb_index
*
* @param string type XMLDB_INDEX_UNIQUE, XMLDB_INDEX_NOTUNIQUE
* @param array fields an array of fieldnames to build the index over
*/
function set_attributes($type, $fields) {
$this->unique = !empty($type) ? true : false;
$this->fields = $fields;
}
/**
* Get the index unique
*/
function getUnique() {
return $this->unique;
}
/**
* Set the index unique
*/
function setUnique($unique = true) {
$this->unique = $unique;
}
/**
* Set the index fields
*/
function setFields($fields) {
$this->fields = $fields;
}
/**
* Get the index fields
*/
function &getFields() {
return $this->fields;
}
/**
* Load data from XML to the index
*/
function arr2xmldb_index($xmlarr) {
$result = true;
/// Debug the table
/// traverse_xmlize($xmlarr); //Debug
/// print_object ($GLOBALS['traverse_array']); //Debug
/// $GLOBALS['traverse_array']=""; //Debug
/// Process key attributes (name, unique, fields, comment, previous, next)
if (isset($xmlarr['@']['NAME'])) {
$this->name = trim($xmlarr['@']['NAME']);
} else {
$this->errormsg = 'Missing NAME attribute';
$this->debug($this->errormsg);
$result = false;
}
if (isset($xmlarr['@']['UNIQUE'])) {
$unique = strtolower(trim($xmlarr['@']['UNIQUE']));
if ($unique == 'true') {
$this->unique = true;
} else if ($unique == 'false') {
$this->unique = false;
} else {
$this->errormsg = 'Incorrect UNIQUE attribute (true/false allowed)';
$this->debug($this->errormsg);
$result = false;
}
} else {
$this->errormsg = 'Undefined UNIQUE attribute';
$this->debug($this->errormsg);
$result = false;
}
if (isset($xmlarr['@']['FIELDS'])) {
$fields = strtolower(trim($xmlarr['@']['FIELDS']));
if ($fields) {
$fieldsarr = explode(',',$fields);
if ($fieldsarr) {
foreach ($fieldsarr as $key => $element) {
$fieldsarr [$key] = trim($element);
}
} else {
$this->errormsg = 'Incorrect FIELDS attribute (comma separated of fields)';
$this->debug($this->errormsg);
$result = false;
}
} else {
$this->errormsg = 'Empty FIELDS attribute';
$this->debug($this->errormsg);
$result = false;
}
} else {
$this->errormsg = 'Missing FIELDS attribute';
$this->debug($this->errormsg);
$result = false;
}
/// Finally, set the array of fields
$this->fields = $fieldsarr;
if (isset($xmlarr['@']['COMMENT'])) {
$this->comment = trim($xmlarr['@']['COMMENT']);
}
if (isset($xmlarr['@']['PREVIOUS'])) {
$this->previous = trim($xmlarr['@']['PREVIOUS']);
}
if (isset($xmlarr['@']['NEXT'])) {
$this->next = trim($xmlarr['@']['NEXT']);
}
/// Set some attributes
if ($result) {
$this->loaded = true;
}
$this->calculateHash();
return $result;
}
/**
* This function calculate and set the hash of one xmldb_index
*/
function calculateHash($recursive = false) {
if (!$this->loaded) {
$this->hash = NULL;
} else {
$key = $this->unique . implode (', ', $this->fields);
$this->hash = md5($key);
}
}
/**
*This function will output the XML text for one index
*/
function xmlOutput() {
$o = '';
$o.= ' <INDEX NAME="' . $this->name . '"';
if ($this->unique) {
$unique = 'true';
} else {
$unique = 'false';
}
$o.= ' UNIQUE="' . $unique . '"';
$o.= ' FIELDS="' . implode(', ', $this->fields) . '"';
if ($this->comment) {
$o.= ' COMMENT="' . htmlspecialchars($this->comment) . '"';
}
if ($this->previous) {
$o.= ' PREVIOUS="' . $this->previous . '"';
}
if ($this->next) {
$o.= ' NEXT="' . $this->next . '"';
}
$o.= '/>' . "\n";
return $o;
}
/**
* This function will set all the attributes of the xmldb_index object
* based on information passed in one ADOindex
*/
function setFromADOIndex($adoindex) {
/// Set the unique field
$this->unique = false;
/// Set the fields, converting all them to lowercase
$fields = array_flip(array_change_key_case(array_flip($adoindex['columns'])));
$this->fields = $fields;
/// Some more fields
$this->loaded = true;
$this->changed = true;
}
/**
* Returns the PHP code needed to define one xmldb_index
*/
function getPHP() {
$result = '';
/// The type
$unique = $this->getUnique();
if (!empty($unique)) {
$result .= 'XMLDB_INDEX_UNIQUE, ';
} else {
$result .= 'XMLDB_INDEX_NOTUNIQUE, ';
}
/// The fields
$indexfields = $this->getFields();
if (!empty($indexfields)) {
$result .= 'array(' . "'". implode("', '", $indexfields) . "')";
} else {
$result .= 'null';
}
/// Return result
return $result;
}
/**
* Shows info in a readable format
*/
function readableInfo() {
$o = '';
/// unique
if ($this->unique) {
$o .= 'unique';
} else {
$o .= 'not unique';
}
/// fields
$o .= ' (' . implode(', ', $this->fields) . ')';
return $o;
}
/**
* Validates the index restrictions.
*
* The error message should not be localised because it is intended for developers,
* end users and admins should never see these problems!
*
* @param xmldb_table $xmldb_table optional when object is table
* @return string null if ok, error message if problem found
*/
function validateDefinition(xmldb_table $xmldb_table=null) {
if (!$xmldb_table) {
return 'Invalid xmldb_index->validateDefinition() call, $xmldb_table si required.';
}
$total = 0;
foreach ($this->getFields() as $fieldname) {
if (!$field = $xmldb_table->getField($fieldname)) {
// argh, we do not have the fields loaded yet, this should not happen during install
continue;
}
switch ($field->getType()) {
case XMLDB_TYPE_INTEGER:
$total += 8; // big int
break;
case XMLDB_TYPE_NUMBER:
$total += 12; // this is just a guess
break;
case XMLDB_TYPE_FLOAT:
$total += 8; // double precision
break;
case XMLDB_TYPE_CHAR:
if ($field->getLength() > self::INDEX_MAX_BYTES / 3) {
return 'Invalid index definition in table {'.$xmldb_table->getName(). '}: XMLDB_TYPE_CHAR field "'.$field->getName().'" can not be indexed because it is too long.'
.' Limit is '.(self::INDEX_MAX_BYTES/3).' chars.';
}
$total += ($field->getLength() * 3); // the most complex utf-8 chars have 3 bytes
break;
case XMLDB_TYPE_TEXT:
return 'Invalid index definition in table {'.$xmldb_table->getName(). '}: XMLDB_TYPE_TEXT field "'.$field->getName().'" can not be indexed';
break;
case XMLDB_TYPE_BINARY:
return 'Invalid index definition in table {'.$xmldb_table->getName(). '}: XMLDB_TYPE_BINARY field "'.$field->getName().'" can not be indexed';
break;
case XMLDB_TYPE_DATETIME:
$total += 8; // this is just a guess
break;
case XMLDB_TYPE_TIMESTAMP:
$total += 8; // this is just a guess
break;
}
}
if ($total > self::INDEX_COMPOSED_MAX_BYTES) {
return 'Invalid index definition in table {'.$xmldb_table->getName(). '}: the composed index on fields "'.implode(',', $this->getFields()).'" is too long.'
.' Limit is '.self::INDEX_COMPOSED_MAX_BYTES.' bytes / '.(self::INDEX_COMPOSED_MAX_BYTES/3).' chars.';
}
return null;
}
}