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Top Forums Shell Programming and Scripting Select record with MAX value in MySQL Post 302433719 by chebarbudo on Wednesday 30th of June 2010 10:26:31 AM
Old 06-30-2010
Time is indeed an issue given the fast growing number of uploaded files.
I isolated one operation: retrieve the file id on 300,000 records.
With a massive update, it takes about 75 seconds.
With a one by one update, I started clocking more than an hour ago and it's not even finished.

Anyway, thank you very much for helping me go deeper in the structure of my database. It was very interesting.

Cheers
Santiago

---------- Post updated at 15:11 ---------- Previous update was at 15:06 ----------

Usually there's a way to reward people who help with bits.
I can't find the button anymore. Do you know where it is?

---------- Post updated at 15:24 ---------- Previous update was at 15:11 ----------

I stopped the query because I needed my CPU ;o)
Trying to extrapolate the number of records already processed, I evaluated that the one by one update is around 2,000 times longer than the massive update.

---------- Post updated at 15:26 ---------- Previous update was at 15:24 ----------

I forgot to mention that I think the incredible difference is certainly due to the well chosen indexes you told me to create.
 

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CGI::Session::Driver::mysql(3)				User Contributed Perl Documentation			    CGI::Session::Driver::mysql(3)

NAME
CGI::Session::Driver::mysql - CGI::Session driver for MySQL database SYNOPSIS
$s = new CGI::Session( 'driver:mysql', $sid); $s = new CGI::Session( 'driver:mysql', $sid, { DataSource => 'dbi:mysql:test', User => 'sherzodr', Password => 'hello' }); $s = new CGI::Session( 'driver:mysql', $sid, { Handle => $dbh } ); DESCRIPTION
mysql stores session records in a MySQL table. For details see CGI::Session::Driver::DBI, its parent class. It's especially important for the MySQL driver that the session ID column be defined as a primary key, or at least "unique", like this: CREATE TABLE sessions ( id CHAR(32) NOT NULL PRIMARY KEY, a_session TEXT NOT NULL ); To use different column names, change the 'create table' statement, and then simply do this: $s = new CGI::Session('driver:mysql', undef, { TableName=>'session', IdColName=>'my_id', DataColName=>'my_data', DataSource=>'dbi:mysql:project', }); or $s = new CGI::Session('driver:mysql', undef, { TableName=>'session', IdColName=>'my_id', DataColName=>'my_data', Handle=>$dbh, }); DRIVER ARGUMENTS mysql driver supports all the arguments documented in CGI::Session::Driver::DBI. In addition, DataSource argument can optionally leave leading "dbi:mysql:" string out: $s = new CGI::Session( 'driver:mysql', $sid, {DataSource=>'shopping_cart'}); # is the same as: $s = new CGI::Session( 'driver:mysql', $sid, {DataSource=>'dbi:mysql:shopping_cart'}); BACKWARDS COMPATIBILITY As of V 4.30, the global variable $CGI::Session::MySQL::TABLE_NAME cannot be used to set the session table's name. This is due to changes in CGI::Session::Driver's new() method, which now allows the table's name to be changed (as well as allowing both the 'id' column name and the 'a_session' column name to be changed). See the documentation for CGI::Session::Driver::DBI for details. In particular, the new syntax for "new()" applies to all database drivers, whereas the old - and bad - global variable method only applied to MySQL. Alternately, call $session -> table_name('new_name') just after creating the session object if you wish to change the session table's name. LICENSING
For support and licensing see CGI::Session. perl v5.16.3 2008-07-16 CGI::Session::Driver::mysql(3)
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