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From:Rolando Edwards Date:January 10 2011 4:42pm
Subject:RE: Reading .MYD file of Mysql Tables
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In reality, you better off manipulating the MyISAM tables via SQL.

However, if you really are that adventurous about low-level reads of MyISAM tables, I have
a crazy suggestion for you !!!

The old MySQL book used as reference to MySQL 3.23/4.0 describes manipulating a MyISAM
table with an API that reminds me so much of manipulating DBF files via the
DBASE/Clipper/FoxPro programming language.

The book is called "MySQL Reference Manual" (ISBN 0-596-00265-3 ,Published June 2002)
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dstripbooks&field-keywords=0-596-00265-3
It was Chapter 6, pages 512,513 Section 6.4.2 HANDLER Syntax.

This same information appears at the following URLs:
http://dev.mysql.com/doc/refman/5.5/en/handler.html
http://download.oracle.com/docs/cd/E17952_01/refman-5.0-en/handler.html

Keep mind that this is a read-only MyISAM API. No low-level writes are available with that
API.

If you need to edit the MyISAM table structure, you should definitely used ALTER TABLE.

However, if you really are that adventurous about table structure manipulation of MyISAM
tables, I have a crazy suggestion for you !!!

A more recent book, called "High Performance MySQL, Second Edition" (ISBN 0-0596-10171-8,
Published June 2008)
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dstripbooks&field-keywords=0-596-10171-8
has a section "Speeding up ALTER TABLE" on Pages 146-149 on how to doctor the .MYI file to
add new columns and the "gotchas" in doing it that way.

If you want to writes and updated to column data in a MyISAM table, I have no crazy
suggestions except one : Download the C source code for the MyISAM storage engine, study
it, and have fun with it.

If you just need faster write performance on MyISAM tables, use one or both of the
following:
1) INSERT DELAYED for a single row (be prepared to suffer up to one second of data loss in
the event of a crash)
2) LOAD DATA INFILE for bulk loading of data (please set bulk_insert_buffer_size to
something like 512M)
3) More suggestions at
http://kevin.vanzonneveld.net/techblog/article/improve_mysql_insert_performance/

I hope these ramblings of mine helped. Please write back to the MySQL Lists and let us all
know what you tried and if it worked. Have a good day !!!

Rolando A. Edwards
MySQL DBA (SCMDBA)

155 Avenue of the Americas, Fifth Floor
New York, NY 10013
212-625-5307 (Work)
201-660-3221 (Cell)
AIM & Skype : RolandoLogicWorx
redwards@stripped
http://www.linkedin.com/in/rolandoedwards


-----Original Message-----
From: Adarsh Sharma [mailto:adarsh.sharma@stripped] 
Sent: Sunday, January 09, 2011 11:14 PM
To: mysql@stripped
Subject: Reading .MYD file of Mysql Tables
Dear all,

I am facing a issue which should be resolved by editing .MYD file of a 
Table.

I know there are 3 files foe a MyISAM table in Mysql but i want to read 
and edit some changes in .MYD file.

If it is possible , Can anyone PLease tell me the way to do this.


Thanks & Regards

Adarsh Sharma

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Thread
Reading .MYD file of Mysql TablesAdarsh Sharma10 Jan
  • Re: Reading .MYD file of Mysql TablesReindl Harald10 Jan
  • RE: Reading .MYD file of Mysql TablesRolando Edwards10 Jan