Parameter(s) need to take care when setting replication over WAN

[Ryan Chan]

Hello,

I am setting MySQL (5.0) replication over WAN for backup purpose (with
SSL enabled).

I have read the document:
http://dev.mysql.com/doc/refman/5.0/en/replication.html, and wonder if
any special tunning needed for using replication over WAN.


Are there any configuration parameter(s) need special handling? What I
understand are:

-  --master-connect-retry=60
- --master-retry-count=86400

Any others?


Thanks.

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Storage of UTF-8 char in MySQL

[Ryan Chan]

According to this document:
http://dev.mysql.com/doc/refman/5.0/en/charset-unicode.html

It said MySQL support UTF-8 using one to three bytes per character.

But I have created a test table:

-- create table test ( c char(5) ) default charset =utf8;

From the table status, the data length is alway a multiple of 16.

So how does it support 3 byte UTF-8 in practice?


Thanks

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int(10) va int(11)

[Ryan Chan]

Assume MySQL int range (unsigned) is from 0 to 4294967295

There are total 10 digits.

Why a lot of tutorial in the web tell you to declare,

e.g.

 CREATE TABLE t1  (f INT(11) UNSIGNED);

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Re: Why UTF8 need 24bit in MySQL?

[Ryan Chan]

Hi,


On Tue, Jun 8, 2010 at 12:44 AM, Warren Young war...@etr-usa.com wrote:
  The Unicode consortium has stated that Unicode will
 never require more than 21 bits per character[*], and 24 bits is the next
 even multiple of 8 up from that.

Maybe off topic, but just curious...If 3 bytes is enough for all
Unicode codepoint, then what is the user of 4byte UTF-8 ?

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Why UTF8 need 24bit in MySQL?

[Ryan Chan]

http://dev.mysql.com/doc/refman/5.0/en/charset-unicode.html

Since MySQL only support BMP, so in fact 16 bit is needed actually?

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Table level locking when inserting auto-increment PK to InnoDB

[Ryan Chan]

Hey.

Back to few years ago, InnoDB require table level locking when
inserting auto-increment PK to the table, and Heikki said there will
be a fix.

Is this problem still exist now?

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Re: Help saving MySQL

[Ryan Chan]

On Sun, Dec 13, 2009 at 11:48 AM, Michael Dykman mdyk...@gmail.com wrote:
 I hope the only reason this thread  is so quiet is because we are all
 busy notifying our friends.  There are a hell of a lot more users
 invested in MySQL than those who read this list.  Spread the word!


Let's stand up today to face the evil!

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Table size vs Memory requirements?

[Ryan Chan]

Hello,

Is it common heard from people that if you have large table (assume
MyISAM in my case), you need large memory in order to have the
key/index in memory for performance, otherwise, table scan on disk is
slow.

But how to estimate how much memory I need?

Consider a simple case, a MyISAM table is 10GB in size, with 2GB
index, how much memory I need?


Thanks.

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