Eric wrote:
Main problem is that query is done in a database of more than 2Go and it
will be difficult to mail it. ;=)
I try with several versions of mysql and php from mysql 4.1.18 to last
5.x and php 4.4.0 to 5.x and don't find significant change in performance.
If it can help here is the loop.
for($debut=$deb;$debut < $fin;$debut += $range){
$end = $debut + $range;
$query = "select avg(total) from `histo_perfs_x` where id1 =
'".$id1."' and id2 = '".addslashes($id2)."' and date > '".$debut."' and
date < '".$end."'";
$result = mysql_query($query) or die("La requete :$query a echouee.");
if(!$result)$databar_total[$j][$i]= 0;
else {
$ligne = mysql_fetch_array($result);
if($ligne[0] != "")$databar_total[$j][$i]=$ligne[0]; else
$databar_total[$j][$i]= "-";
}
}
Excellent! Well yes, 2G of data is too big to mail! However, generating
2G of synthetic test data is no problem at all.
However to do this, a little more information is needed:
1/ A create statement for the table histo_perfs_x, along with its
indexes, explicitly specifying if using an engine other than myisam.
2/ An estimate of proportion of the histo_perfs_x table a query like:
select avg(total) from histo_perfs_x
where id1 = ? and id2 = ? and date > ? and date < ?;
is likely to scan (for typical values of the 4 bind variables).
3/ (If possible) the output of explain of the above query so we can
duplicate the access plan.
4/ The number of iterations you were using in the php loop for your test.
Cheers
Mark
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