MSSQL在PHP Query中运行缓慢

Question

I have a PHP page that's slow whenever it goes to query a MSSQL database. I'm using the latest PHP and the standard SQL odbc drivers to the connect to the database. When accessing the page My sql profiler goes crazy.The query is displayed then

exec sp_cursorfetch 180150003,2,1,1
go

performs about 240 times before finally

exec sp_cursorclose 180150003
go 

occurs and the page is displayed.

This is the query causing the headache:

    <?php
    $con = odbc_connect('Hesk','Trace_user','*******');
    $Assets = odbc_exec($con, "SELECT  AssetName,           AssetID From viewAssets ORDER BY [AssetName];");
?>
<table Border ="0"   width="100%">
<tr>
<td style="text-align:right" width="150"><?php echo $hesklang   ['asset']; ?>: <font class="important"></font>
</td>
<td width = "80%"><select name ="asset">
<option value=""></option>
<?php
    while ($row = odbc_fetch_array($Assets))
    {
    echo '<option value="' . $row['AssetID'] . '"' .            (($_SESSION['c_asset'] == $row['AssetID']) ? '              selected="selected"' : '')
    . '>' . $row['AssetName']. '</option>';
    }
    odbc_close($con);
?>
</select></td>
</tr>
</table>

Any idea how my code is causing this performance holdup?

Answer 1

It looks like the odbc_exec functions use cursors under the hood. I'm not entirely sure who thought that was a good idea, but it's not. Cursors are notoriously bad performers and generally a really bad idea unless you simply have no other way.

One option is to change your odbc_connect call to have the SQL_CUR_USE_ODBC flag. A better option is to use the native drivers.

http://cct.me.ntut.edu.tw/ccteducation/chchting/aiahtm/computer/phphelp/function.odbc-connect.php.htm