Re: DBI::quote problem - Paul DuBois - com.mysql.lists.mysql

17 messages in com.mysql.lists.mysqlRe: DBI::quote problem

From	Sent On	Attachments
d e l d h a n o a	06 Sep 1999 21:15
Eugene Miretskiy	07 Sep 1999 13:29
Joshua Chamas	07 Sep 1999 13:42
Eugene Miretskiy	07 Sep 1999 14:00
Joshua Chamas	07 Sep 1999 14:12
Eugene Miretskiy	07 Sep 1999 14:24
Joshua Chamas	07 Sep 1999 14:29
Jules Bean	07 Sep 1999 16:20
Joshua Chamas	07 Sep 1999 16:34
Joshua Chamas	07 Sep 1999 16:43
Paul DuBois	07 Sep 1999 16:48
Joshua Chamas	07 Sep 1999 16:57
Joshua Chamas	07 Sep 1999 17:34
Jules Bean	08 Sep 1999 01:00
Jules Bean	08 Sep 1999 01:01
Michael Widenius	08 Sep 1999 05:42
Joshua Chamas	09 Sep 1999 04:20

Subject:	Re: DBI::quote problem
From:	Paul DuBois (pa...@snake.net)
Date:	09/07/1999 04:48:24 PM
List:	com.mysql.lists.mysql

At 6:35 PM -0500 9/7/99, Joshua Chamas wrote:

I didn't think you could prepare *any* queries with mysql. I thought that DBI::prepare was basically a no-op when using the Mysql driver (well, not quite - it stores the string locally, and does the ? substitution, but that's a local perl-side issue) - and I'd be surprised if it affected query speed much at all. (Unless, of course your overhead is perl, but that'd be surprising)

I don't know what's going on in the background, but between DBD::mysql & mysqld, there is a 35% speedup when preparing & caching cursors for simple insert statements. Supposedly there are no "server-side cursors" so I'm guessing its a client side thing.

What happens if you run your sets of statements in a different order? You may simply be seeing an effect of OS-level disk cacheing.

Here's a little benchmark that you can run:

use Benchmark;

# you supply the $dbi connection # create a database called spiders with a spider_id auto # incrementing column

timethis(2000, sub { my $isth = $dbi->prepare("insert into spiders (spider_id) values (NULL)"); my $nsth = $dbi->prepare("select last_insert_id()"); $isth->execute(); $nsth->execute(); $nsth->fetchrow_array; $nsth->finish; }); timethis(2000, sub { my $isth = $dbi->prepare_cached("insert into spiders (spider_id) values (NULL)"); my $nsth = $dbi->prepare_cached("select last_insert_id()"); $isth->execute(); $nsth->execute(); $nsth->fetchrow_array; $nsth->finish; });

prompt> bench_insert.pl timethis 2000: 10 secs (10.32 usr 0.00 sys = 10.32 cpu) timethis 2000: 7 secs ( 6.63 usr 0.00 sys = 6.63 cpu)

-- Joshua

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