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<?php
/**
* Snap Database utils
*
* Standard: PSR-2
* @link http://www.php-fig.org/psr/psr-2
*
* @package SnapLib
* @copyright (c) 2017, Snapcreek LLC
* @license https://opensource.org/licenses/GPL-3.0 GNU Public License
*
*/
defined('ABSPATH') || defined('DUPXABSPATH') || exit;
class DupLiteSnapLibDB
{
const CACHE_PREFIX_PRIMARY_KEY_COLUMN = 'pkcol_';
const DB_ENGINE_MYSQL = 'MySQL';
const DB_ENGINE_MARIA = 'MariaDB';
const DB_ENGINE_PERCONA = 'Percona';
private static $cache = array();
/**
*
* @param mysqli $dbh // Database connection handle
* @param string $tableName
* @return string|string[] // return array if primary key is composite key
* @throws Exception
*/
public static function getUniqueIndexColumn(\mysqli $dbh, $tableName, $logCallback = null)
{
$cacheKey = self::CACHE_PREFIX_PRIMARY_KEY_COLUMN.$tableName;
if (!isset(self::$cache[$cacheKey])) {
$query = 'SHOW COLUMNS FROM `'.mysqli_real_escape_string($dbh, $tableName).'` WHERE `Key` IN ("PRI","UNI")';
if (($result = mysqli_query($dbh, $query)) === false) {
if (is_callable($logCallback)) {
call_user_func($logCallback, $dbh, $result, $query);
}
throw new Exception('SHOW KEYS QUERY ERROR: '.mysqli_error($dbh));
}
if (is_callable($logCallback)) {
call_user_func($logCallback, $dbh, $result, $query);
}
if ($result->num_rows == 0) {
self::$cache[$cacheKey] = false;
} else {
$primary = false;
$unique = false;
while ($row = $result->fetch_assoc()) {
switch ($row['Key']) {
case 'PRI':
if ($primary === false) {
$primary = $row['Field'];
} else {
if (is_scalar($primary)) {
$primary = array($primary);
}
$primary[] = $row['Field'];
}
break;
case 'UNI':
$unique = $row['Field'];
break;
default:
break;
}
}
if ($primary !== false) {
self::$cache[$cacheKey] = $primary;
} else if ($unique !== false) {
self::$cache[$cacheKey] = $unique;
} else {
self::$cache[$cacheKey] = false;
}
}
$result->free();
}
return self::$cache[$cacheKey];
}
/**
*
* @param array $row
* @param string|string[] $indexColumns
* @return string|string[]
*/
public static function getOffsetFromRowAssoc($row, $indexColumns, $lastOffset)
{
if (is_array($indexColumns)) {
$result = array();
foreach ($indexColumns as $col) {
$result[$col] = isset($row[$col]) ? $row[$col] : 0;
}
return $result;
} else if (strlen($indexColumns) > 0) {
return isset($row[$indexColumns]) ? $row[$indexColumns] : 0;
} else {
return $lastOffset + 1;
}
}
/**
* This function performs a select by structuring the primary key as offset if the table has a primary key.
* For optimization issues, no checks are performed on the input query and it is assumed that the select has at least a where value.
* If there are no conditions, you still have to perform an always true condition, for example
* SELECT * FROM `copy1_postmeta` WHERE 1
*
* @param mysqli $dbh // Database connection handle
* @param string $query
* @param string $table
* @param int $offset
* @param int $limit // 0 no limit
* @param mixed $lastRowOffset // last offset to use on next function call
* @return mysqli_result
* @throws Exception // exception on query fail
*/
public static function selectUsingPrimaryKeyAsOffset(\mysqli $dbh, $query, $table, $offset, $limit, &$lastRowOffset = null, $logCallback = null)
{
$where = '';
$orderby = '';
$offsetStr = '';
$limitStr = $limit > 0 ? ' LIMIT '.$limit : '';
if (($primaryColumn = self::getUniqueIndexColumn($dbh, $table, $logCallback)) == false) {
$offsetStr = ' OFFSET '.(is_scalar($offset) ? $offset : 0);
} else {
if (is_array($primaryColumn)) {
// COMPOSITE KEY
$orderByCols = array();
foreach ($primaryColumn as $colIndex => $col) {
$orderByCols[] = '`'.$col.'` ASC';
}
$orderby = ' ORDER BY '.implode(',', $orderByCols);
} else {
$orderby = ' ORDER BY `'.$primaryColumn.'` ASC';
}
$where = self::getOffsetKeyCondition($dbh, $primaryColumn, $offset);
}
$query .= $where.$orderby.$limitStr.$offsetStr;
if (($result = mysqli_query($dbh, $query)) === false) {
if (is_callable($logCallback)) {
call_user_func($logCallback, $dbh, $result, $query);
}
throw new Exception('SELECT ERROR: '.mysqli_error($dbh));
}
if (is_callable($logCallback)) {
call_user_func($logCallback, $dbh, $result, $query);
}
if ($primaryColumn == false) {
$lastRowOffset = $offset + $result->num_rows;
} else {
if ($result->num_rows == 0) {
$lastRowOffset = $offset;
} else {
$result->data_seek(($result->num_rows - 1));
$row = $result->fetch_assoc();
if (is_array($primaryColumn)) {
$lastRowOffset = array();
foreach ($primaryColumn as $col) {
$lastRowOffset[$col] = $row[$col];
}
} else {
$lastRowOffset = $row[$primaryColumn];
}
$result->data_seek(0);
}
}
return $result;
}
/**
* Depending on the structure type of the primary key returns the condition to position at the right offset
*
* @param string|string[] $primaryColumn
* @param mixed $offset
* @return string
*/
protected static function getOffsetKeyCondition(\mysqli $dbh, $primaryColumn, $offset)
{
$condition = '';
if ($offset === 0) {
return '';
}
// COUPOUND KEY
if (is_array($primaryColumn)) {
foreach ($primaryColumn as $colIndex => $col) {
if (is_array($offset) && isset($offset[$col]) && $offset[$col] > 0) {
$condition .= ($colIndex == 0 ? '' : ' OR ');
$condition .= ' (';
for ($prevColIndex = 0; $prevColIndex < $colIndex; $prevColIndex++) {
$condition .= ' `'.$primaryColumn[$prevColIndex].'` = "'.mysqli_real_escape_string($dbh, $offset[$primaryColumn[$prevColIndex]]).'" AND ';
}
$condition .= ' `'.$col.'` > "'.mysqli_real_escape_string($dbh, $offset[$col]).'")';
}
}
} else {
$condition = '`'.$primaryColumn.'` > "'.mysqli_real_escape_string($dbh, (is_scalar($offset) ? $offset : 0)).'"';
}
return (strlen($condition) ? ' AND ('.$condition.')' : '');
}
public static function getDBEngine(\mysqli $dbh)
{
$result = mysqli_query($dbh, "SHOW VARIABLES LIKE 'version%'");
$rows = @mysqli_fetch_all($result);
@mysqli_free_result($result);
$version = isset($rows[0][1]) ? $rows[0][1] : false;
$versionComment = isset($rows[1][1]) ? $rows[1][1] : false;
//Default is mysql
if ($version === false && $versionComment === false) {
return self::DB_ENGINE_MYSQL;
}
if (stripos($version, 'maria') !== false || stripos($versionComment, 'maria') !== false) {
return self::DB_ENGINE_MARIA;
}
if (stripos($version, 'percona') !== false || stripos($versionComment, 'percona') !== false) {
return self::DB_ENGINE_PERCONA;
}
return self::DB_ENGINE_MYSQL;
}
}
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