From: Marcus Bointon
Date: October 27 2011 1:09pm
Subject: Re: Master-Master -> duplicate entry
List-Archive: http://lists.mysql.com/replication/2252
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On 27 Oct 2011, at 14:55, Ricardo wrote:

> Currently I have as a a pk, an autoincrement value as int(9)
>=20
> I should be able to reach 999.999.999 records, right?
>=20
> Placing the autoincrement as 10, I will have 10x less so I will have =
99.999.999 (99 million records).=20
>=20
> Is this correct?
>=20
> Since I already have around 125.000.000 records, I guessing =
implementing this without clearing some records, will pretty much ruin =
everything.
>=20
> Any advice?
>=20
> I can use an autoincrement of 5 for instance. Guessing having master 1 =
with offset of 1 and master 2 with an offset of 2, I feel i will not =
have much of a problem here.

The number after the field isn't anything to do with its stored size or =
value range, just how it's displayed. MySQL uses typical binary ranges =
for its numeric types, so an unsigned integer is typically 32 bits, =
giving a range of 0 to 4294967295 (about 4 billion). There are other =
integer types: tinyint(8 bits) smallint(16 bits), mediumint(24 bits), =
int(32 bits), bigint(64 bits), all of which may be signed or unsigned. =
PHP only handles signed ints so the biggest value it can handle in =
32-bits is 2147483647, which is the limit you're most likely to hit. =
Using a signed integer type for an autoinc field is just a waste of a =
bit as you'll never use the negative half of the number range.

Signed integers default to int(11) because they can have up to 10 =
base-10 digits plus a sign character; unsigned defaults to int(10) =
because it doesn't need the extra space for the sign. Both store their =
values in 32 bits.

Marcus
--=20
Marcus Bointon
Synchromedia Limited: Creators of http://www.smartmessages.net/
UK info@hand CRM solutions
marcus@stripped | http://www.synchromedia.co.uk/