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Full Discussion: Multithreading program
Top Forums Shell Programming and Scripting Multithreading program Post 302358213 by adderek on Thursday 1st of October 2009 04:59:00 PM
Old 10-01-2009
1. Multithreading means "you must be stupid to do this in shell"
2. Loading 1 huge set of data at once is in general faster than loading dzylion of microsets in parallel
3. In Oracle you have SQLLoader and it has mode called "direct" - check if you cannot use similar thing in MySQL (I have no experience in MySQL)
4. If there is no option of direct loading of the data you might want to use bulk load methods
5. Loading in multiple threads means that you most probably are going to create dzylion of connections... if creation and closing of a single connection takes 1 second and inserting 1 row of data takes 0.0000000001 of a second... imagine how much slower would it work if you create multiple threads
6. Transaction is your friend - until you commit your application (executable compiled application) should be able to insert rows with only a minor performance decrease - if this is really really required by you then you might assume that there is a probable chance that you might need to create an application that loads row-by-row and commits the changes afterward.... really no bulk methods? I was thinking that MySQL is a developed database but it is not if there are no bulk operations.
 

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MYSQLDUMPSLOW(1)					       MySQL Database System						  MYSQLDUMPSLOW(1)

NAME
mysqldumpslow - Summarize slow query log files SYNOPSIS
mysqldumpslow [options] [log_file ...] DESCRIPTION
The MySQL slow query log contains information about queries that take a long time to execute (see Section 5.2.5, "The Slow Query Log"). mysqldumpslow parses MySQL slow query log files and prints a summary of their contents. Normally, mysqldumpslow groups queries that are similar except for the particular values of number and string data values. It "abstracts" these values to N and 'S' when displaying summary output. The -a and -n options can be used to modify value abstracting behavior. Invoke mysqldumpslow like this: shell> mysqldumpslow [options] [log_file ...] mysqldumpslow supports the following options. o --help Display a help message and exit. o -a Do not abstract all numbers to N and strings to 'S'. o --debug, -d Run in debug mode. o -g pattern Consider only queries that match the (grep-style) pattern. o -h host_name Host name of MySQL server for *-slow.log file name. The value can contain a wildcare. The default is * (match all). o -i name Name of server instance (if using mysql.server startup script). o -l Do not subtract lock time from total time. o -n N Abstract numbers with at least N digits within names. o -r Reverse the sort order. o -s sort_type How to sort the output. The value of sort_type should be chosen from the following list: o t, at: Sort by query time or average query time o l, al: Sort by lock time or average lock time o s, as: Sort by rows sent or average rows sent o c: Sort by count o -t N Display only the first N queries in the output. o --verbose, -v Verbose mode. Print more information about what the program does. Example of usage: shell> mysqldumpslow Reading mysql slow query log from /usr/local/mysql/data/mysqld51-apple-slow.log Count: 1 Time=4.32s (4s) Lock=0.00s (0s) Rows=0.0 (0), root[root]@localhost insert into t2 select * from t1 Count: 3 Time=2.53s (7s) Lock=0.00s (0s) Rows=0.0 (0), root[root]@localhost insert into t2 select * from t1 limit N Count: 3 Time=2.13s (6s) Lock=0.00s (0s) Rows=0.0 (0), root[root]@localhost insert into t1 select * from t1 COPYRIGHT
Copyright 2007-2008 MySQL AB, 2008-2010 Sun Microsystems, Inc. This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see http://www.gnu.org/licenses/. SEE ALSO
For more information, please refer to the MySQL Reference Manual, which may already be installed locally and which is also available online at http://dev.mysql.com/doc/. AUTHOR
Sun Microsystems, Inc. (http://www.mysql.com/). MySQL 5.1 04/06/2010 MYSQLDUMPSLOW(1)
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