This DBI statement is taking too long and I need to speed things up:
my $sth = $dbh->prepare("select * from campaigns where mw_export='yes'
+ and last_update > ?");
$sth->execute(last_transfer{'campaigns'});
while(my $result = $sth->fetchrow_hashref()) {
print "It takes me over 30 minutes to print this!!!\n";
}
I have about 40,000 rows with each row containing about 200 fields. My program hangs for a loooooong time. So I know I have a few options:
1. Use indexes.
2. Use fetchrow_arrayref instead of fetchrow_hashref.
I created two indexes but didn't notice any speed improvement:
alter table campaigns add index mw_export (mw_export);
alter table campaigns add index last_update (last_update);
Should I create a different type of index? Those are the SQL statements that I used.
The other option is to use fetchrow_arrayref. But I *need* to have $result as a hash ref. Would it be okay to convert the array ref to a hash ref? What would be the best way to do that?
I heard that fetchrow_arrayref is way faster than its hashref counterpart.
Any other things that I could try?
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.
|